Free Tutorials
Internet
What is Internet
Internet Games
Learn TCP IP
HTML
Learn HTML
Learn CSS
Learn XML
Learn WML
Database
Learn Access
Learn Data-VB
Learn Oracle
Learn SQL
Programming
Learn ActiveX
Learn C++
Learn CGI_Perl
Learn Interdev
Learn Java
Learn JavaScript
Learn Vbscript
Learn VisualBasic
Learn VC++
Operating systems
Learn RedHat
Learn Unix
Learn Winnt

Chapter 14

Extending Web Pages Through Design-Time Controls

If you are a developer, you recognize the importance of an application's design. Throughout this guide, I have tried to emphasize the design as the crux of your application. A design can make or break an application. You also probably realize the importance of the design stage of a development project. It is imperative that you spend the proper time contemplating the aspects of the application design so that the system will execute successfully when the user runs the application.

These design aspects can be applied to the use of design-time controls. Microsoft has introduced a new kind of control to enable you to design specific functionality into your application that will execute when the system is run. In the same way that your application exhibits its characteristics and design concepts when it is run, design-time controls reveal their behavior at runtime. These controls enable you to focus on designing robust functionality into your application.

ToChapter's lesson focuses on the use of design-time controls within your Web-based applications. First, the lesson explains and defines the concept of a design-time control, teaching you what a design-time control is and how it can be used within your web pages. Next, the lesson explains the difference between design-time controls and regular ActiveX controls.

The middle part of the Chapter presents one of the more robust design-time controls that can be used in your web pages. The Data Command control can be used to provide rich database integration for your applications. You learn how to insert and use design-time controls like the Data Command control. You also discover the remnants of a design-time control placed within your web page document.

The final lesson for the Chapter outlines how to truly use and integrate these exciting new controls into your applications. You will discover how to extend the power and functionality of your application through the use of design-time controls.

Defining Design-Time ActiveX Controls

Based on yesterChapter's lesson, you should now understand the concept of an ActiveX control. You realize that you can use these controls to build the interface for your application. You also know that ActiveX controls exhibit their presence and functionality when the user initiates the application. But, what is a design-time control? Does this mean that I can use this control when I design my application, but not when I run it? This section answers these questions and more, and provides a basic definition for a design-time control.

A design-time control is an important new control, developed specifically for the Web, that enables you to place rich functionality in your application without additional overhead. Design-time controls are the Diet Coke of the computer interface--same great taste with half the calories!

Design-time controls enable you to take advantage of the same benefits as ActiveX controls during the time of application design. This means that you can visually set the properties and characteristics of the control, similar to ActiveX controls. The distinguishing factor is that design-time controls don't incur the overhead cost at runtime. When you insert a design-time control into your web page, you establish the characteristics of the control. These property attributes are saved as text within the context of the document. The text contains special instructions based on properties that you have designed for the control. When the user runs the application, the actual control that you used to develop these instructions is disabled, and the instructions execute the designed functionality. In other words, you receive the same powerful functionality with a lower overhead cost, hence the Diet Coke analogy.

New Term: A design-time control is a special type of ActiveX control that enables you to inte- grate specific properties and behavior characteristics when designing your applications. These controls insert instructions into your documents instead of an actual control, thereby reducing the amount of processing overhead in your application.

Design-Time ActiveX Controls Versus ActiveX Controls

While the ActiveX control is typically a graphical object that is used to construct a user interface for your application, the design-time control provides a visual helper at the time of design. This visual aid then works behind the scenes to execute the desired functionality.

With a few exceptions, ActiveX controls are usually visible to you when you're designing your application. You have learned about several controls that enable you to build a graphical user interface. These ActiveX controls include the command button, the radio button, the checkbox, the listbox, the marquee, and so on. You have used some of these controls during the first two weeks. Once you insert the controls on your web page, you establish the property values for the controls to affect their appearance and behavior. At runtime, these controls appear in your web page and provide specific functionality. Runtime refers to the period of time that the user is running the application and executing the code. ActiveX controls contain a binary runtime component that provides additional functionality when the application runs. You incur the overhead of the control being alive during application runtime to receive the additional functionality.

Design-time controls, on the other hand, don't contain a runtime component. Design-time controls aren't visible when the user runs the application. You can use these controls while designing your web pages to provide powerful functionality to your application. These controls are like wizards that facilitate the construction of your application during the design phase of your development effort. When the user executes the application, the functionality is exhibited in the application without the appearance of the design-time control. It's control might not be visible at runtime, but its effects are evident to the user.

Design-Time Controls Make Effective Parents

A design-time control has a similar relationship and responsibility to the application as a parent has to a child. A parent is charged with raising children. This task includes providing the proper guidance and instruction, so that the child can thrive when he or she becomes an adult. The parent serves as a counselor and coach who visually provides an example in his or her actions and his or her speech. When the child becomes an adult, he or she will exhibit behaviors, values, and characteristics that have been taught by the parents. As a parent, I can already see the effects of this relationship in my two small children.

A design-time control provides a similar guide to the web pages and application. The design-time control affects your application by the properties and characteristics that are set for the control. This information is stored in the context of the web page documents. In a sense, the web page is affected by the instruction, or "teaching," of the design-time control. The control tells the web page what behaviors to exhibit.

You can think of the runtime environment as adulthood for the web page that includes the code produced by the design-time control. During runtime, the control is no longer around to help. This is analogous to the parent who is no longer around to instruct the child, now an adult, what to do. The newly independent adult must live his or her own life, using the characteristics and values that the parents taught him or her as a child. Similarly, the runtime text code that was created in the web page must execute independently of the design-time control when the application is executed. Although the design-time control parent is no longer visibly around, this code exhibits the properties and characteristics that were instilled during design-time. Figure 14.1 illustrates both the parent/child and the design-time control/run-time code relationship.

Figure 14.1.

The design-time control--an effective parent.

The Origin of Design-Time Controls

Visual InterDev is one of the first tools to use design-time controls as a part of the development environment. Design-time controls, like regular ActiveX controls, are based on Microsoft's Component Object Model (COM). This model provides a standard definition and structure for all design-time controls. Because a design-time control is constructed based on COM, applications can access its functionality through a standard method. You can build a design-time control with hard-core languages like C and C++, as well as more intuitive languages such as Visual Basic. You also can build design-time controls with the Java programming language.


NOTE: You must use Visual Basic version 5 or higher to build a design-time or ActiveX control. Microsoft also offers a trimmed down version of Visual Basic 5.0 called the Visual Basic Control Creation Edition. This product is specifically targeted at developers who want to build design-time and ActiveX controls. You will get a chance to learn about this product and how to use it to build a design-time control on Chapter 16, "Building Design-Time ActiveX Controls."

Once you become familiar with using design-time controls, I think you will want to rush out and build your controls. You will realize their benefit and structure and recognize the importance of their reusability across your development team. You might even begin by developing reusable design-time controls across your development team.

After you become appreciated internally, you could expand your reach by authoring controls that can be used commercially by a plethora of developers. Whatever the case, I think you will see how easy it is to use and develop design-time controls. You will also appreciate their power and capability.

Visual InterDev provides many design-time controls that you can integrate into your application. The controls generate both HTML and scripting code that can be used in a variety of ways, including the creation of the following items:

  • HTML content

  • Client-side scripting

  • ActiveX controls

  • Java applets

  • Server-side scripting

  • Active Server Components

Within your Visual InterDev application, you can integrate design-time controls in your client- and server-side components. Some of the more powerful Visual InterDev design-time controls enable you to integrate rich and robust database functionality into your application. The next few sections explain and explore these exciting new controls.

Understanding Design-Time Controls

This section is for those intrigued minds who wonder how a design-time control can achieve its purpose without visibly appearing in the application at runtime. This part of the lesson explains how to insert a design-time control into your application. Once you understand the process, I will review the inner workings of the design-time control, then explain how these controls accomplish their tasks.

Inserting a Design-Time Control

Design-time controls are typically placed within a web page or an Active Server Page. The design-time control must be installed and registered on the machine where it is used. This requirement is the same as regular ActiveX controls. Once registered, the design-time control can be used within the context of your application.

To insert a design-time control, open the ASP or HTML file and right-click the mouse at the desired position in the file. Select Insert ActiveX Control from the shortcut menu. When the Insert ActiveX Control tabbed dialog window is displayed, click the Design-time tab. You will then be presented with a list of all of the registered design-time controls. Figure 14.2 depicts a list of available design-time controls that are included with Visual InterDev.

Figure 14.2.

Selecting a design-time control.

You can pick the design-time control from the list and click OK. The Object Editor that you learned about yesterChapter will then be activated. You can use this visual editor to set the properties of the design-time control. Figure 14.3 depicts the Data Command control, a powerful database design-time control, as seen through the eyes of the Object Editor.

Figure 14.3.

Setting the properties for a design-time control.

The Object Editor was covered in yesterChapter's lesson. You can use the Object Editor to configure the properties and characteristics of the control. After you set the properties of the design-time control, it is inserted into your web page document. Later in the Chapter the lesson teaches you how to set the properties of some of the more robust design-time controls. For now, you should focus on learning the basic structure of all design-time controls. The next section teaches you how to recognize the presence of a design-time control within a web page. The lesson also defines the general attributes of a design-time control.

Reviewing the Remnants of a Design-Time Control

Just exactly what does a design-time control look like? What magic is going on behind the scenes to enable such elaborate behavior? How does a design-time control affect my application? This section answers these questions, walks you through a review of the rem-nants of a design-time control, and explains the basic structure for all design-time controls as seen within an HTML or ASP document. Figure 14.4 depicts a design-time control as seen within the confines of an ASP file.

Figure 14.4.

The markings of a design-time control.

As you can see from Figure 14.4, the design-time control somewhat resembles an ActiveX control. The control is denoted by the <OBJECT> tag and contains an ID, CLASSID, and some parameters similar to an ActiveX control. The design-time control differs from an ActiveX control in that it is initially denoted with the METADATA comment. The design-time control also visually appears in green within the ASP document. The runtime text for the control is highlighted and displays below the ending <OBJECT> tag. The next few sections examine the appearance and structure of a design-time control.

Examining the Structure of a Design-Time Control

The METADATA comment is used to denote the start of the design-time control. The TYPE attribute is equal to the value of Designer Control, which is true of all design-time controls. The startspan attribute indicates the beginning of the METADATA comment and causes this line of the comment to be passed over. Another reason for using the METADATA comments to surround a design-time control is to prevent instantiation of the object.

One of the key points and benefits about design-time controls that has been noted in this lesson is that these controls don't incur the overhead of regular ActiveX controls. Because the object is surrounded by comments, it won't be instantiated. Only the runtime text will persist, thereby reducing the overhead incurred by the application.

The <OBJECT> tag enables you to work with the control and visually sets the properties of the control. In a sense, the <OBJECT> tag informs Visual InterDev that the control is an object. This information enables you to easily edit the properties of the design-time control. You can right-click the mouse within the <OBJECT> tags to display the shortcut menu, as seen in Fig-ure 14.5.

Figure 14.5.

Editing the properties of the design-time control.

The option to edit a design-time control differs slightly from an ActiveX control. As you can see from Figure 14.5, you select Edit Design-time Control from the list of menu items to alter the properties of your control. This action activates the Object Editor and displays your design-time control.

The attributes and parameters contained within the <OBJECT> tags for the design-time control help to generally define the runtime code for the control. The code in this example is displayed as script and explicitly defines the behavior of the control. This scripting code is what the application and browser are going to execute at runtime. The object declaration is passed over, and the runtime text is the only thing that is noticed and processed. The ending METADATA comment contains the endspan attribute, which signifies to the browser the end of the runtime text for the design-time control.

Editing the Script for a Design-Time Control

In the previous example, the runtime script that was displayed was automatically generated based on properties defined in the Object Editor. You may be wondering whether Visual InterDev enables you to extend and customize this scripting logic. The answer is yes. There might be cases in which you need to customize the generated logic for the control. The only thing you need to be aware of concerns the METADATA comment tags. When these comment tags are present, opening the control after you have made changes to the script replaces your customized code with the generated scripting logic defined by the control's properties. To avoid this situation, remove the METADATA comment tags.

Taking Charge with the Data Command Control

Now that you understand the basic structure of a design-time control, the lesson explores some of the more robust design-time controls. Visual InterDev includes several design-time controls that provide rich database functionality for your application. This section covers the Data Command control, which you received a preview of in the previous section.

The Data Command design-time control uses a database connection to perform a basic query against a database. The Data Command control creates a Recordset object that you can use to perform your queries. You learned about the Recordset object on Chapter 8, "Communicating with a Database." As a refresher, the Recordset object represents all of the records in a specified table. You can use the Recordset object to retrieve the individual rows within a designated table.


NOTE: The rest of the lesson assumes that you have a valid database connection for your project. To use the database design-time controls, you must first add a database connection to your project. Refer to the lesson on Chapter 8 for a refresher on how to accomplish this task. The examples that are used rely on the Publishers database connection that was created earlier in the week.

The Data Command design-time control should be used for retrieving and modifying a single row within a table. You will discover other design-time controls in the next section that enable you to work with multiple rows of a table. You can specify command text properties for the Data Command control that indicate the type of command to execute against the database. This information is used with the Recordset object to perform the specified type of database action against the desired row within a table.

Inserting a Data Command Control

To insert the Data Command design-time control into your application, open the file that will contain the control. Click the right mouse button at the desired position within the document and select Insert ActiveX Control from the shortcut menu. Click the Design-time tab and choose Data Command Control from the list, as seen in Figure 14.6.

Figure 14.6.

Selecting the Data Command design-time control.


TIP: You should use Active Server Pages to handle your database logic. When inserting a database design-time control, choose an ASP file instead of an HTML file.

After you have chosen the Data Command control, click the OK button. You will then be able to edit the properties of the control using the Object Editor. Figure 14.7 displays the Data Command control and its property window.

The Data Command Properties window consists of the following tabs:

Control tab
Advanced tab
Parameters tab
All tab

Each of these tabs is explained in the next few sections.

Figure 14.7.

The Data Command control Properties window.

The Control Tab

The Control tab is the default display tab for the Properties window. You saw a preview of this window in Figure 14.7. The first field on the window is the ID field, which enables you to define a name for the control. You use this ID to reference the control within your code.

The Data Connection drop-down listbox enables you to specify the data connection for the control. Any active data connections for the project will be displayed in the list. For this example, I chose the database connection to the Pubs database that was defined at the first part of this week's lesson. The Command to Submit frame contains several options that enable you to specify the type of SQL command to execute.

The first drop-down listbox on the frame is the Command Type, which enables you to indicate the type of command to send to the database. Table 14.1 displays the available choices for the Command Type.

Table 14.1. Command types for the Data Command control.

Type Description
SQL Enables you to format an SQL statement
Stored Procedure Specifies the use of a stored procedure
Table Specifies the use of a database table
View Specifies the use of a database view

The Command Text drop-down listbox indicates the command that will be sent to the database. The Command Type that you choose affects the contents of the Command Text drop-down listbox as well as the behavior of the other controls in this frame. For example, if you select Stored Procedure for the Command Type, the contents of the Command Text drop-down listbox display the available stored procedures in the database. Also, the SQL Builder push button is disabled because you're choosing to use a pre-defined SQL procedure that already exists. The SQL Builder push button enables you to use the Query Designer within Visual InterDev to create and construct an SQL database call.

If you choose SQL for the Command Type, the SQL Builder push button is enabled, allowing you to construct your SQL statement. You also can choose to directly enter the SQL statement in the Command Text field. A Command Type of Table will disable the SQL Builder push button and display a list of the available tables within the database in the Command Type drop-down listbox. Similarly, you can select View for the Command Type, which will disable the SQL Builder push button and populate the Command Text drop-down listbox with the views that are contained within the database. Finally, the Copy Fields push button enables you to copy the fields from the database table for insertion into your web page document. When you click this button, the Copy Fields dialog window displays as shown in Figure 14.8.

Figure 14.8.

Copying fields from a database table.

The Copy Fields dialog window displays the available column fields contained within a database table in the list box on the left-hand side of the window. You can double-click a field to move it to the Fields to Copy listbox. You also can select the available field and click the single arrow button that points to the right to place the field into the Fields to Copy listbox.

Pressing the double-arrow button that points to the right moves all of the available fields into the Fields to Copy listbox. You can remove fields that have been selected to be copied in a similar manner. You can either double-click the item within the Fields to Copy listbox or select the item and click the single arrow button that points to the left. To deselect all of the fields to be copied, click the double-arrow button that points in the direction of the Available Fields listbox. The fields that you choose are copied to the clipboard. You can then insert them into your web page document using the text editor of your choice. This feature provides an easy way to access the values of the columns within a row in your table.

The Advanced Tab

The Advanced tab enables you to customize your database commands. In many cases, you can accept the defaults for this tab. Advanced database developers typically use this dialog to fine-tune the performance of the application. For example, you can specify the type of cursor to use with a query.

You also can choose the type of locking scheme that you want to use for database requests among different users. This option can be used with applications and databases that support high-volume transaction processing. For instance, if your application will have users contending for the same data, you may want to use a locking scheme that prevents users from overwriting changes to the same data. You can choose from among several database locking schemes within the Advanced tab to meet the needs of your application. You also can set the numbers of records to cache into local memory. The Advanced tab enables you to prepare, or compile, an SQL statement when it's initially executed. After the first user executes the SQL, performance will increase for additional users, because the statement has already been compiled against the database. Figure 14.9 displays the options on the Advanced tabbed dialog window.

Figure 14.9.

The Advanced tab.

The Parameters Tab

The Parameters tab is specifically used with stored procedures. If you choose Stored Procedure for your Command Type on the Control property page, you can then input values for the parameters for the stored procedure, if necessary.

The All Tab

You can use this property page to view all of the properties for the Data Command design-time control. Figure 14.10 displays the properties for a sample Data Command control.

Figure 14.10.

Viewing all of the properties for the control.

As you can see from Figure 14.10, this view is similar to the Properties dialog window for ActiveX controls. All of the properties are listed along with their values. This view maintains all of the values that are assigned on the individual property pages for the control. You can use the All tab to get a comprehensive view of the available properties and to assign their values at one time instead of tabbing through the individual pages.

Building an SQL Statement with the Query Designer

I stated that you could use the SQL Builder push button on the Control tab to construct an SQL statement for your Data Command design-time control. Remember, you must select a Command Type of SQL to enable the SQL Builder push button. When you click the SQL Builder push button, the Query Designer will, by default, be activated.


NOTE: The Query Designer is automatically displayed if it's the sole SQL builder installed on your machine. You can use other commercially available SQL builders with this button. If another type of SQL builder is installed on your system, you will be presented with a list of the available SQL builders on your machine. The Query Designer, as well as the other products, will be shown in the list. You can then select a tool from the list and build your SQL statement.

Figure 14.11 demonstrates an example of choosing SQL for the Command Type and pressing the SQL Builder push button.

Figure 14.11.

Using the Query Designer to build your query.

You can then use the Query Designer to construct your SQL statement. You learned how to use the Query Designer and all of its panes on Chapter 9, "Using the Visual Data Tools for Maximum Productivity." First, you need to drag and drop the tables that you want to use into the Query Designer workspace. This example uses the Authors table, and uses the Diagram pane to build an SQL query that selects all of the columns from the Authors table, as shown in Figure 14.12.

Figure 14.12.

Constructing the SQL statement.

Once the query is built, you can save the query by selecting Save from the File menu. This option saves the query within the context of the Data Command control. In other words, you won't be prompted to provide a name for the query, as you were in the previous lesson when you were creating an independent query against the database. The Query Designer knows that you're creating this query for a database design-time control and saves the SQL statement in the Command Text for the Data Command control. When you close the Query Designer window, you should notice that the SQL statement that is built is displayed in the Command Text drop-down listbox on the Control property page, as shown in Figure 14.13.


NOTE: You can use all of the features of the Query Designer while building your SQL statement. You might want to test the results of your SQL statement before you save it, for example. You can execute the statement and view the results in the Results pane, just as you did during the lesson on Chapter 9. I will illustrate this process when I discuss the Data Range design-time controls.

Figure 14.13.

A newly created SQL statement.

Examining the Results

Once you have finished setting the properties for the Data Command control, you can return to the ASP document to view the results. The <OBJECT> tag attributes as well as the runtime text are based on the properties that you define for the control. Listing 14.1 displays the code that was placed in the ASP file based on the previous example.

Listing 14.1. The ASP representation of the Data Command design-time control.

<!--METADATA TYPE="DesignerControl" startspan
<OBJECT ID="DataCommand1" WIDTH=151 HEIGHT=24
CLASSID="CLSID:7FAEED80-9D58-11CF-8F68-00AA006D27C2">
<PARAM NAME="_Version" VALUE="65536">
<PARAM NAME="_Version" VALUE="65536">
<PARAM NAME="_ExtentX" VALUE="3986">
<PARAM NAME="_ExtentY" VALUE="635">
<PARAM NAME="_StockProps" VALUE="0">
<PARAM NAME="DataConnection" VALUE="pubs">
<PARAM NAME="CommandText" VALUE="SELECT authors.* FROM authors">
</OBJECT>
-->
<%
Set pubs = Server.CreateObject("ADODB.Connection")
pubs.ConnectionTimeout = Session("pubs_ConnectionTimeout")
pubs.CommandTimeout = Session("pubs_CommandTimeout")
pubs.Open Session("pubs_ConnectionString"), Session("pubs_RuntimeUserName"), Session("pubs_RuntimePassword")
Set cmdTemp = Server.CreateObject("ADODB.Command")
Set DataCommand1 = Server.CreateObject("ADODB.Recordset")
cmdTemp.CommandText = "SELECT authors.* FROM authors"
cmdTemp.CommandType = 1
Set cmdTemp.ActiveConnection = pubs
DataCommand1.Open cmdTemp, , 0, 1
%>
<!--METADATA TYPE="DesignerControl" endspan-->

In this listing, you can see both the object declaration and the runtime text. As stated before, the object declaration is enclosed in comments and won't be interpreted by the browser. The runtime text is the only item that will persist when the application is executed.

The first line of the runtime text creates a database connection object and stores the instance of this object in the pubs variable. The next line exhibits how the global.asa file and the ASP file that contains the database control work together to connect to the database. Using the pubs object that was created in the first line of this runtime text, the ConnectionTimeout and CommandTimeout properties are established, based on the database connection that was created for the project. The connection information can be found in the Session_OnStart procedure within the global.asa file. The information in the global.asa file stores general property information about the database connection. This information is used to help the ASP create the connection dynamically when it's needed. The ConnectionTimeout property defines the maximum length of time for the connection, while the CommandTimeout property specifies the maximum duration for execution of the SQL command.

Next, a session is opened for the pubs object, again, based on information contained in the Session_OnStart procedure in the global.asa file. The user name and password are used to connect to the database. The cmdTemp variable is used to create a Command object. This object is used later in the code to capture the SQL command to execute against the database. The DataCommand1 variable is used to create the Recordset object. After this object is created, the Recordset object is opened, using the SQL statement as a parameter. In this case, the CommandText object that is contained in the cmdTemp variable selects all of the columns from the Authors table.

The Data Range Controls

The Data Range Header and Footer controls provide two very robust design-time controls. These controls enable you to retrieve multiple records from a database. You can use the Data Range Header control to create the Recordset object and query and to begin retrieving rows from the database table. The Data Range Footer control works in conjunction with the Data Range Header control and enables you to page through the records in the database.

The Data Range Header Control

The process of inserting a Data Range Header design-time control is very similar to that of inserting the Data Command design-time control. Open the ASP file and right-click the mouse at the desired position for the control. Select Insert ActiveX Control from the shortcut menu and click the Design-time tab. Choose Data Range Header Control and click OK. The Object Editor activates, and the control and its property window are displayed as shown in Figure 14.14.

Figure 14.14.

The Data Range Header design-time control.

The fields in the top section of the Control property page are identical in meaning to the Data Command control.

There are some new fields that pertain to the Data Range Header control. The Bar Alignment enables you to align the database navigation bar on a web page. This bar provide navigation controls for the user to traverse the records in the database. The Range Type enables you to specify what type of fields will be used to display the data. You can specify either Text, Form, or Table format.

In the example pictured in Figure 14.14, I chose Text for the Range Type. The Record Paging checkbox and Page Size field are used together to define the number of rows that will be displayed on a page. If Record Paging is checked, you can indicate the number of rows that are displayed on your web page in the Page Size field. When the Page Size field is greater than zero, the navigation bar is also displayed on the page. If you don't select the Record Paging checkbox, all of the records for the query are displayed on one page.


NOTE: To use Record Paging, you must set the Cursor Type on the Advanced property page to either Keyset or Static. These values are explained below.

The Advanced and Parameters property pages for the Data Range Header control contain the same fields as the Data Command control. Because the Data Range control pertains more to multiple rows of data, an explanation of the various cursor types is covered in this section. Table 14.2 explains the types of cursors that you can set using the Advanced property page.

Table 14.2. Available cursor types.

Type Description
Forward Only Enables you to move only to the next record
Keyset Enables you to scroll through data in any direction; reflects up-to-date information concerning the database except for additions by new users
Dynamic Enables you to scroll through data in any direction; reflects the most up-to-date information including additions by other users
Static Enables you to scroll through data in any direction; contains a snapshot of the data at a certain point in time

As with the Data Command design-time control, you can use the Query Designer to build a query for the Data Range Header design-time control. After selecting Save from the File menu, you can view the design-time control within the ASP. For this example, I have chosen to build an SQL statement that selects the first and last name, phone number, and contract indicator from the Authors table. Listing 14.2 displays the Data Range Header design-time control within the context of an ASP.

Listing 14.2. The ASP representation of the Data Range Header design-time control.

<!--METADATA TYPE="DesignerControl" startspan
<OBJECT ID="DataRangeHdr1" WIDTH=151 HEIGHT=24
CLASSID="CLSID:F602E721-A281-11CF-A5B7-0080C73AAC7E">
<PARAM NAME="_Version" VALUE="65536">
<PARAM NAME="_Version" VALUE="65536">
<PARAM NAME="_ExtentX" VALUE="3986">
<PARAM NAME="_ExtentY" VALUE="635">
<PARAM NAME="_StockProps" VALUE="0">
<PARAM NAME="DataConnection" VALUE="pubs">
<PARAM NAME="CommandText" VALUE="SELECT au_fname, au_lname, phone, contract 
FROM authors">
<PARAM NAME="CursorType" VALUE="1">
<PARAM NAME="PageSize" VALUE="10">
</OBJECT>
-->
<%
fHideNavBar = False
fHideNumber = False
fHideRequery = False
fHideRule = False
stQueryString = ""
fEmptyRecordset = False
fFirstPass = True
fNeedRecordset = False
fNoRecordset = False
tBarAlignment = "Left"
tHeaderName = "DataRangeHdr1"
tPageSize = 10
tPagingMove = ""
tRangeType = "Text"
tRecordsProcessed = 0
If Not IsEmpty(Request("DataRangeHdr1_PagingMove")) Then
tPagingMove = Trim(Request("DataRangeHdr1_PagingMove"))
End If
If IsEmpty(Session("DataRangeHdr1_Recordset")) Then
fNeedRecordset = True
Else
If Session("DataRangeHdr1_Recordset") Is Nothing Then
fNeedRecordset = True
Else
Set DataRangeHdr1 = Session("DataRangeHdr1_Recordset")
End If
End If
If fNeedRecordset Then
Set pubs = Server.CreateObject("ADODB.Connection")
pubs.ConnectionTimeout = Session("pubs_ConnectionTimeout")
pubs.CommandTimeout = Session("pubs_CommandTimeout")
pubs.Open Session("pubs_ConnectionString"), Session("pubs_RuntimeUserName"), Session("pubs_RuntimePassword")
Set cmdTemp = Server.CreateObject("ADODB.Command")
Set DataRangeHdr1 = Server.CreateObject("ADODB.Recordset")
cmdTemp.CommandText = "SELECT au_fname, au_lname, phone, contract FROM authors"
cmdTemp.CommandType = 1
Set cmdTemp.ActiveConnection = pubs
DataRangeHdr1.Open cmdTemp, , 1, 1
End If
On Error Resume Next
If DataRangeHdr1.BOF And DataRangeHdr1.EOF Then fEmptyRecordset = True
On Error Goto 0
If Err Then fEmptyRecordset = True
DataRangeHdr1.PageSize = tPageSize
If Not IsEmpty(Session("DataRangeHdr1_Filter")) And Not fEmptyRecordset Then
DataRangeHdr1.Filter = Session("DataRangeHdr1_Filter")
If DataRangeHdr1.BOF And DataRangeHdr1.EOF Then fEmptyRecordset = True
End If
If IsEmpty(Session("DataRangeHdr1_PageSize")) Then Session("DataRangeHdr1_
PageSize") = tPageSize
If IsEmpty(Session("DataRangeHdr1_AbsolutePage")) Then Session("DataRangeHdr1_
AbsolutePage") = 1
If Session("DataRangeHdr1_PageSize") <> tPageSize Then
tCurRec = ((Session("DataRangeHdr1_AbsolutePage") - 1) * Session("DataRangeHdr1_
PageSize")) + 1
tNewPage = Int(tCurRec / tPageSize)
If tCurRec Mod tPageSize <> 0 Then
tNewPage = tNewPage + 1
End If
If tNewPage = 0 Then tNewPage = 1
Session("DataRangeHdr1_PageSize") = tPageSize
Session("DataRangeHdr1_AbsolutePage") = tNewPage
End If
If fEmptyRecordset Then
fHideNavBar = True
fHideRule = True
Else
Select Case tPagingMove
Case "Requery"
DataRangeHdr1.Requery
Case "<<"
Session("DataRangeHdr1_AbsolutePage") = 1
Case "<"
If Session("DataRangeHdr1_AbsolutePage") > 1 Then
Session("DataRangeHdr1_AbsolutePage") = Session Â("DataRangeHdr1_AbsolutePage") - 1
End If
Case ">"
If Not DataRangeHdr1.EOF Then
Session("DataRangeHdr1_AbsolutePage") = Session Â("DataRangeHdr1_AbsolutePage") + 1
End If
Case ">>"
Session("DataRangeHdr1_AbsolutePage") = DataRangeHdr1.PageCount
End Select
DataRangeHdr1.AbsolutePage = Session("DataRangeHdr1_AbsolutePage")
If DataRangeHdr1.EOF Then
Session("DataRangeHdr1_AbsolutePage") = Session Â("DataRangeHdr1_AbsolutePage") - 1
DataRangeHdr1.AbsolutePage = Session("DataRangeHdr1_AbsolutePage")
End If
End If
Do
If fEmptyRecordset Then Exit Do
If tRecordsProcessed = tPageSize Then Exit Do
If Not fFirstPass Then
DataRangeHdr1.MoveNext
Else
fFirstPass = False
End If
If DataRangeHdr1.EOF Then Exit Do
tRecordsProcessed = tRecordsProcessed + 1
`WHERE IS THE REST OF THE DO LOOP???
%>
<!--METADATA TYPE="DesignerControl" endspan-->

As you can see, the Data Range Header control generated a plethora of code from just a few simple clicks of the mouse. I bet you can think of a million ways to spend the time that can be saved by using a visual control such as the Data Range Header control. The logic that is created basically creates the database connection and opens the Recordset object using the SQL statement that I constructed with the Query Designer. The other logic that is generated facilitates the ability to page through the database records.

I stated previously that the Data Range Header and Footer controls are used together. There is an error in Listing 14.2, because I haven't inserted the Data Range Footer control. Can you pick out the error? My comments within the code provide a significant visual aid to help you locate the error. The Data Range Footer design-time control must be inserted into the ASP to complete the logic for the Data Range Header design-time control.

The Data Range Footer Control

The process to insert the Data Range Footer design-time control is identical to the process for inserting the Data Range Header design-time control. Select the Data Range Footer Control from the list in the Insert ActiveX Control dialog window. The Data Range Footer control will be displayed in the Object Editor, as shown in Figure 14.15.

The property page for the Data Range Footer control contains one page that enables you to set all of the properties for the control at one time. After you set the properties, you can select Save from the File menu to save the control. You then can view the remnants of the Data Range Footer control within the ASP file. Listing 14.3 displays a more complete ASP file that includes the Data Range Footer design-time control.

Figure 14.15.

The Data Range Footer design-time control.

Listing 14.3. Completing the set.

<!--METADATA TYPE="DesignerControl" startspan
<OBJECT ID="DataRangeHdr1" WIDTH=151 HEIGHT=24
CLASSID="CLSID:F602E721-A281-11CF-A5B7-0080C73AAC7E">
<PARAM NAME="_Version" VALUE="65536">
<PARAM NAME="_Version" VALUE="65536">
<PARAM NAME="_ExtentX" VALUE="3986">
<PARAM NAME="_ExtentY" VALUE="635">
<PARAM NAME="_StockProps" VALUE="0">
<PARAM NAME="DataConnection" VALUE="pubs">
<PARAM NAME="CommandText" VALUE="SELECT au_fname, au_lname, phone, contract 
FROM authors">
<PARAM NAME="CursorType" VALUE="1">
<PARAM NAME="PageSize" VALUE="10">
</OBJECT>
-->
<%
fHideNavBar = False
fHideNumber = False
fHideRequery = False
fHideRule = False
stQueryString = ""
fEmptyRecordset = False
fFirstPass = True
fNeedRecordset = False
fNoRecordset = False
tBarAlignment = "Left"
tHeaderName = "DataRangeHdr1"
tPageSize = 10
tPagingMove = ""
tRangeType = "Text"
tRecordsProcessed = 0
If Not IsEmpty(Request("DataRangeHdr1_PagingMove")) Then
tPagingMove = Trim(Request("DataRangeHdr1_PagingMove"))
End If
If IsEmpty(Session("DataRangeHdr1_Recordset")) Then
fNeedRecordset = True
Else
If Session("DataRangeHdr1_Recordset") Is Nothing Then
fNeedRecordset = True
Else
Set DataRangeHdr1 = Session("DataRangeHdr1_Recordset")
End If
End If
If fNeedRecordset Then
Set pubs = Server.CreateObject("ADODB.Connection")
pubs.ConnectionTimeout = Session("pubs_ConnectionTimeout")
pubs.CommandTimeout = Session("pubs_CommandTimeout")
pubs.Open Session("pubs_ConnectionString"), Session("pubs_RuntimeUserName"), Session("pubs_RuntimePassword")
Set cmdTemp = Server.CreateObject("ADODB.Command")
Set DataRangeHdr1 = Server.CreateObject("ADODB.Recordset")
cmdTemp.CommandText = "SELECT au_fname, au_lname, phone, contract FROM authors"
cmdTemp.CommandType = 1
Set cmdTemp.ActiveConnection = pubs
DataRangeHdr1.Open cmdTemp, , 1, 1
End If
On Error Resume Next
If DataRangeHdr1.BOF And DataRangeHdr1.EOF Then fEmptyRecordset = True
On Error Goto 0
If Err Then fEmptyRecordset = True
DataRangeHdr1.PageSize = tPageSize
If Not IsEmpty(Session("DataRangeHdr1_Filter")) And Not fEmptyRecordset Then
DataRangeHdr1.Filter = Session("DataRangeHdr1_Filter")
If DataRangeHdr1.BOF And DataRangeHdr1.EOF Then fEmptyRecordset = True
End If
If IsEmpty(Session("DataRangeHdr1_PageSize")) Then Session("DataRangeHdr1_
PageSize") = tPageSize
If IsEmpty(Session("DataRangeHdr1_AbsolutePage")) Then Session("DataRangeHdr1_
AbsolutePage") = 1
If Session("DataRangeHdr1_PageSize") <> tPageSize Then
tCurRec = ((Session("DataRangeHdr1_AbsolutePage") - 1) * Session("DataRangeHdr1_
PageSize")) + 1
tNewPage = Int(tCurRec / tPageSize)
If tCurRec Mod tPageSize <> 0 Then
tNewPage = tNewPage + 1
End If
If tNewPage = 0 Then tNewPage = 1
Session("DataRangeHdr1_PageSize") = tPageSize
Session("DataRangeHdr1_AbsolutePage") = tNewPage
End If
If fEmptyRecordset Then
fHideNavBar = True
fHideRule = True
Else
Select Case tPagingMove
Case "Requery"
DataRangeHdr1.Requery
Case "<<"
Session("DataRangeHdr1_AbsolutePage") = 1
Case "<"
If Session("DataRangeHdr1_AbsolutePage") > 1 Then
Session("DataRangeHdr1_AbsolutePage") = Session Â("DataRangeHdr1_AbsolutePage") - 1
End If
Case ">"
If Not DataRangeHdr1.EOF Then
Session("DataRangeHdr1_AbsolutePage") = Session Â("DataRangeHdr1_AbsolutePage") + 1
End If
Case ">>"
Session("DataRangeHdr1_AbsolutePage") = DataRangeHdr1.PageCount
End Select
DataRangeHdr1.AbsolutePage = Session("DataRangeHdr1_AbsolutePage")
If DataRangeHdr1.EOF Then
Session("DataRangeHdr1_AbsolutePage") = Session Â("DataRangeHdr1_AbsolutePage") - 1
DataRangeHdr1.AbsolutePage = Session("DataRangeHdr1_AbsolutePage")
End If
End If
Do
If fEmptyRecordset Then Exit Do
If tRecordsProcessed = tPageSize Then Exit Do
If Not fFirstPass Then
DataRangeHdr1.MoveNext
Else
fFirstPass = False
End If
If DataRangeHdr1.EOF Then Exit Do
tRecordsProcessed = tRecordsProcessed + 1
%>
<!--METADATA TYPE="DesignerControl" endspan-->
<!--METADATA TYPE="DesignerControl" startspan
<OBJECT ID="DataRangeFtr1" WIDTH=151 HEIGHT=24
CLASSID="CLSID:F602E722-A281-11CF-A5B7-0080C73AAC7E">
<PARAM NAME="_Version" VALUE="65536">
<PARAM NAME="_ExtentX" VALUE="3969">
<PARAM NAME="_ExtentY" VALUE="635">
<PARAM NAME="_StockProps" VALUE="0">
</OBJECT>
-->
<%
Loop
If tRangeType = "Table" Then Response.Write "</TABLE>"
If tPageSize > 0 Then
If Not fHideRule Then Response.Write "<HR>"
If Not fHideNavBar Then
%>
<TABLE WIDTH=100% >
<TR>
<TD WIDTH=100% >
<P ALIGN=<%= tBarAlignment %> >
<FORM ACTION="<%= Request.ServerVariables("PATH_INFO") & stQueryString %>" 
METHOD="POST">
<INPUT TYPE="Submit" NAME="<%= tHeaderName & "_PagingMove" %>"
VALUE="   &lt;&lt;   ">
<INPUT TYPE="Submit" NAME="<%= tHeaderName & "_PagingMove" %>"
VALUE="   &lt;    ">
<INPUT TYPE="Submit" NAME="<%= tHeaderName & "_PagingMove" %>"
VALUE="    &gt;   ">
<INPUT TYPE="Submit" NAME="<%= tHeaderName & "_PagingMove" %>"
VALUE="   &gt;&gt;   ">
<% If Not fHideRequery Then %>
<INPUT TYPE="Submit" NAME="<% =tHeaderName & "_PagingMove" %>"
VALUE=" Requery ">
<% End If %>
</FORM>
</P>
</TD>
<TD VALIGN=MIDDLE ALIGN=RIGHT>
<FONT SIZE=2>
<%
If Not fHideNumber Then
If tPageSize > 1 Then
Response.Write "<NOBR>Page: " & Session(tHeaderName & "_AbsolutePage") & 
"</NOBR>"
Else
Response.Write "<NOBR>Record: " & Session(tHeaderName & "_AbsolutePage") & 
"</NOBR>"
End If
End If
%>
</FONT>
</TD>
</TR>
</TABLE>
<%
End If
End If
%>
<!--METADATA TYPE="DesignerControl" endspan-->

Notice that in this code example the Data Range Footer control nicely completes the Do Loop. The Data Range Footer control does a lot more, though, than simply add the word Loop to the end of the Do Loop. The Data Range Footer control adds complex logic to format the records with the database. Remember, I selected Text as the Range Type for the Data Range Header control. Based on this value, the Data Range Footer control builds the necessary code to format the data in a table. Also, the Data Range Footer control creates the logic for the user to traverse through the database records.

There is one thing left to do to make this code functional. So far, the structure has been developed to execute a query and display the results within a table. The code is useless for an application, because the fields haven't yet been inserted into the code. The following code sample can be inserted before the Data Range Header control in the ASP file to create column names for the table:

<TABLE WIDTH=100% BORDER=1>
<TR><TH>Name</TH><TH>Phone</TH></TR>

This code sample creates two table header columns for the name and phone number. To populate the rows of the table with the database information, you can insert the following lines of code between the Data Range Header and Footer controls in the ASP file:

<TR>
<TD> <%Response.Write DataRangeHdr1("au_fname") & " " & 
DataRangeHdr1("au_lname") %> </TD>
<TD> <%Response.Write DataRangeHdr1("phone")%> </TD>
</TR>

This code sample formats the rows of the table with the names and phone numbers of the people found in the Authors table. In this example, the first name and the last name fields are concatenated together. Listing 14.4 displays the complete code listing for the Author Contact List web page.

Listing 14.4. The Author Contact List.

<%@ LANGUAGE="VBSCRIPT" %>
<HTML>
<HEAD>
<META NAME="GENERATOR" Content="Microsoft Visual InterDev 1.0">
<META HTTP-EQUIV="Content-Type" content="text/html; charset=iso-8859-1">
<TITLE>Contact List</TITLE>
<H3>Author Contact List</H3>
</HEAD>
<BODY>
<TABLE WIDTH=100% BORDER=1>
<TR><TH>Name</TH><TH>Phone</TH></TR>
<!--METADATA TYPE="DesignerControl" startspan
<OBJECT ID="DataRangeHdr1" WIDTH=151 HEIGHT=24
CLASSID="CLSID:F602E721-A281-11CF-A5B7-0080C73AAC7E">
<PARAM NAME="_Version" VALUE="65536">
<PARAM NAME="_Version" VALUE="65536">
<PARAM NAME="_ExtentX" VALUE="3986">
<PARAM NAME="_ExtentY" VALUE="635">
<PARAM NAME="_StockProps" VALUE="0">
<PARAM NAME="DataConnection" VALUE="pubs">
<PARAM NAME="CommandText" VALUE="SELECT au_fname, au_lname, phone, contract 
FROM authors">
<PARAM NAME="CursorType" VALUE="1">
<PARAM NAME="PageSize" VALUE="10">
</OBJECT>
-->
<%
fHideNavBar = False
fHideNumber = False
fHideRequery = False
fHideRule = False
stQueryString = ""
fEmptyRecordset = False
fFirstPass = True
fNeedRecordset = False
fNoRecordset = False
tBarAlignment = "Left"
tHeaderName = "DataRangeHdr1"
tPageSize = 10
tPagingMove = ""
tRangeType = "Text"
tRecordsProcessed = 0
If Not IsEmpty(Request("DataRangeHdr1_PagingMove")) Then
tPagingMove = Trim(Request("DataRangeHdr1_PagingMove"))
End If
If IsEmpty(Session("DataRangeHdr1_Recordset")) Then
fNeedRecordset = True
Else
If Session("DataRangeHdr1_Recordset") Is Nothing Then
fNeedRecordset = True
Else
Set DataRangeHdr1 = Session("DataRangeHdr1_Recordset")
End If
End If
If fNeedRecordset Then
Set pubs = Server.CreateObject("ADODB.Connection")
pubs.ConnectionTimeout = Session("pubs_ConnectionTimeout")
pubs.CommandTimeout = Session("pubs_CommandTimeout")
pubs.Open Session("pubs_ConnectionString"), Session("pubs_RuntimeUserName"), Session("pubs_RuntimePassword")
Set cmdTemp = Server.CreateObject("ADODB.Command")
Set DataRangeHdr1 = Server.CreateObject("ADODB.Recordset")
cmdTemp.CommandText = "SELECT au_fname, au_lname, phone, contract FROM authors"
cmdTemp.CommandType = 1
Set cmdTemp.ActiveConnection = pubs
DataRangeHdr1.Open cmdTemp, , 1, 1
End If
On Error Resume Next
If DataRangeHdr1.BOF And DataRangeHdr1.EOF Then fEmptyRecordset = True
On Error Goto 0
If Err Then fEmptyRecordset = True
DataRangeHdr1.PageSize = tPageSize
If Not IsEmpty(Session("DataRangeHdr1_Filter")) And Not fEmptyRecordset Then
DataRangeHdr1.Filter = Session("DataRangeHdr1_Filter")
If DataRangeHdr1.BOF And DataRangeHdr1.EOF Then fEmptyRecordset = True
End If
If IsEmpty(Session("DataRangeHdr1_PageSize")) Then Session("DataRangeHdr1_
PageSize") = tPageSize
If IsEmpty(Session("DataRangeHdr1_AbsolutePage")) Then Session("DataRangeHdr1_
AbsolutePage") = 1
If Session("DataRangeHdr1_PageSize") <> tPageSize Then
tCurRec = ((Session("DataRangeHdr1_AbsolutePage") - 1) * Session("DataRangeHdr1_
PageSize")) + 1
tNewPage = Int(tCurRec / tPageSize)
If tCurRec Mod tPageSize <> 0 Then
tNewPage = tNewPage + 1
End If
If tNewPage = 0 Then tNewPage = 1
Session("DataRangeHdr1_PageSize") = tPageSize
Session("DataRangeHdr1_AbsolutePage") = tNewPage
End If
If fEmptyRecordset Then
fHideNavBar = True
fHideRule = True
Else
Select Case tPagingMove
Case "Requery"
DataRangeHdr1.Requery
Case "<<"
Session("DataRangeHdr1_AbsolutePage") = 1
Case "<"
If Session("DataRangeHdr1_AbsolutePage") > 1 Then
Session("DataRangeHdr1_AbsolutePage") = Session Â("DataRangeHdr1_AbsolutePage") - 1
End If
Case ">"
If Not DataRangeHdr1.EOF Then
Session("DataRangeHdr1_AbsolutePage") = Session Â("DataRangeHdr1_AbsolutePage") + 1
End If
Case ">>"
Session("DataRangeHdr1_AbsolutePage") = DataRangeHdr1.PageCount
End Select
DataRangeHdr1.AbsolutePage = Session("DataRangeHdr1_AbsolutePage")
If DataRangeHdr1.EOF Then
Session("DataRangeHdr1_AbsolutePage") = Session Â("DataRangeHdr1_AbsolutePage") - 1
DataRangeHdr1.AbsolutePage = Session("DataRangeHdr1_AbsolutePage")
End If
End If
Do
If fEmptyRecordset Then Exit Do
If tRecordsProcessed = tPageSize Then Exit Do
If Not fFirstPass Then
DataRangeHdr1.MoveNext
Else
fFirstPass = False
End If
If DataRangeHdr1.EOF Then Exit Do
tRecordsProcessed = tRecordsProcessed + 1
%>
<!--METADATA TYPE="DesignerControl" endspan-->
<TR>
<TD> <%Response.Write DataRangeHdr1("au_fname") & " " & 
DataRangeHdr1("au_lname") %> </TD>
<TD> <%Response.Write DataRangeHdr1("phone")%> </TD>
</TR>
<!--METADATA TYPE="DesignerControl" startspan
<OBJECT ID="DataRangeFtr1" WIDTH=151 HEIGHT=24
CLASSID="CLSID:F602E722-A281-11CF-A5B7-0080C73AAC7E">
<PARAM NAME="_Version" VALUE="65536">
<PARAM NAME="_ExtentX" VALUE="3969">
<PARAM NAME="_ExtentY" VALUE="635">
<PARAM NAME="_StockProps" VALUE="0">
</OBJECT>
-->
<%
Loop
If tRangeType = "Table" Then Response.Write "</TABLE>"
If tPageSize > 0 Then
If Not fHideRule Then Response.Write "<HR>"
If Not fHideNavBar Then
%>
<TABLE WIDTH=100% >
<TR>
<TD WIDTH=100% >
<P ALIGN=<%= tBarAlignment %> >
<FORM ACTION="<%= Request.ServerVariables("PATH_INFO") & stQueryString %>" 
METHOD="POST">
<INPUT TYPE="Submit" NAME="<%= tHeaderName & "_PagingMove" %>"
VALUE="   &lt;&lt;   ">
<INPUT TYPE="Submit" NAME="<%= tHeaderName & "_PagingMove" %>"
VALUE="   &lt;    ">
<INPUT TYPE="Submit" NAME="<%= tHeaderName & "_PagingMove" %>"
VALUE="    &gt;   ">
<INPUT TYPE="Submit" NAME="<%= tHeaderName & "_PagingMove" %>"
VALUE="   &gt;&gt;   ">
<% If Not fHideRequery Then %>
<INPUT TYPE="Submit" NAME="<% =tHeaderName & "_PagingMove" %>"
VALUE=" Requery ">
<% End If %>
</FORM>
</P>
</TD>
<TD VALIGN=MIDDLE ALIGN=RIGHT>
<FONT SIZE=2>
<%
If Not fHideNumber Then
If tPageSize > 1 Then
Response.Write "<NOBR>Page: " & Session(tHeaderName & "_AbsolutePage") & 
"</NOBR>"
Else
Response.Write "<NOBR>Record: " & Session(tHeaderName & "_AbsolutePage") & 
"</NOBR>"
End If
End If
%>
</FONT>
</TD>
</TR>
</TABLE>
<%
End If
End If
%>
<!--METADATA TYPE="DesignerControl" endspan-->
</BODY>
</HTML>

Figure 14.16 depicts the web page that is created from this code example.

Figure 14.16.

Viewing the authors.

The web page displays a table which contains a list of authors and their phone numbers. You can use the database navigation bar at the bottom of the page to traverse the database records. From this example, I think you can understand the functions of the Data Range Header and Data Range Footer controls. Basically, the Data Range Header control opens the database connection and executes the initial SQL statement.

The Data Range Footer control completes the Data Range Header logic and processes additional records through the use of the navigation bar. These controls are somewhat analogous to a header and footer that you design for your web pages. In Listing 14.4, you learned how to display the database information by inserting the logic to populate the table between the Data Range Header and Footer controls. Similarly, you design a web page to display the main content within the body of the document. In both of these cases, the header and footer provide necessary logic and structure to properly format the data.

Using the Data Range Builder

Now that you have learned how to individually insert the Data Range Header and Footer controls, I bet you would like to discover an easier way to place these controls in your web pages. Visual InterDev, again, lives up to its name by providing a visual wizard to construct and insert both the Data Range Header and Footer controls into your web page document. The Data Range Builder is a special type of wizard called an HTML Builder. You can use HTML Builder to combine HTML and design-time controls or to create pairs of design-time controls.

You can use the Data Range Builder to create a Data Range Header and Data Range Footer control. Open the ASP file and right-click the mouse to display the shortcut menu. Select Insert HTML Using Wizard, as shown in Figure 14.17.

After you select this menu item, the Choose Builder dialog window is displayed. Select the Data Range Wizard from the list. The Data Range Builder Wizard displays, as shown in Figure 14.18.

The Data Range Builder Wizard guides you through the process of creating the Data Range Header and Footer controls. The first window enables you to select how many records to display. You can choose to display all of the records on one page, or you can specify the number of records to display per page. This window also enables you to designate the alignment of the database navigation bar. After you complete your selections, click the Next button to advance to the next window. The second window of the wizard enables you to choose a name for your data range. Figure 14.19 shows the layout of this window.

Figure 14.17.

Selecting Insert HTML Using Wizard.

Figure 14.18.

Specifying the display options.

Figure 14.19.

Naming the data range.

After you click Finish, the Object Editor activates, enabling you to further customize the properties of the Data Range Header control. You can choose the data connection and use the Query Designer to construct your SQL statement. Once you complete this process and close the Object Editor, the Data Range Header and Footer controls are displayed in your ASP file. The Data Range Builder provides a very intuitive and straightforward approach for creating the Data Range Header and Data Range Footer controls.

Integrating Design-Time Controls into Your Application

So far, you have learned how to use the Data Command, Data Range Header, and Data Range Footer design-time controls. The lesson has presented several examples of how to use these controls within your application. In the sections on the Data Range Header and Footer controls, you learned how to format a table with database information. This section explores another use of these controls to create a display form for your data.

Exploring Other Uses of Design-Time Controls

I am going to use the same example that was covered in the previous section and show you how a few minor changes can affect the application that you create. Using a new ASP file, I will cover how to create a Data Range Header and Footer again. Refer to the previous sections on this topic for a refresher. This example starts at the point of defining the Data Range Header control using the Object Editor.

In Listing 14.4, the application displayed the data in a table. I designed this functionality by choosing Text as the Range Type. Other available values include Form and Table. You can pick Form for the Range Type to display data within a form on your web page. Also, for form data, you should choose to display only one record at a time. You can select Record Paging and enter the value of 1 for the Page Size. Remember, you must set the Cursor Type on the Advanced property page to either Keyset or Static to be able to enter a value for the Page Size. Figure 14.20 displays these choices for the Data Range Header control as it appears in the Object Editor.

Figure 14.20.

Setting the control properties.

Next, you need to build a query for the control. I have chosen to build a query that selects the first name, last name, address, city, state, and ZIP code for all rows contained in the Authors table. Figure 14.21 displays this query on the Control property page.

The final task that needs to be completed is to copy the fields to the clipboard. You can click the Copy Fields push button and select the fields that you want to copy. These fields are inserted later into the ASP file to enable you to display the database information on the form. Figure 14.22 displays the fields to be inserted into the ASP file.

Figure 14.21.

Displaying the query for the control.

Figure 14.22.

Copying the fields.

After you close the Object Editor, the Data Range Header design-time control is displayed in the ASP file. You then can create the Data Range Footer design-time control. The final step is to paste the copied fields in your ASP file between the Data Range Header and Data Range Footer controls. Listing 14.5 displays the resulting ASP file that is created from the previous steps.

Listing 14.5. The Author Contact display form.

<%@ LANGUAGE="VBSCRIPT" %>
<HTML>
<HEAD>
<META NAME="GENERATOR" Content="Microsoft Visual InterDev 1.0">
<META HTTP-EQUIV="Content-Type" content="text/html; charset=iso-8859-1">
<TITLE>Author Form</TITLE>
<H3>Author Contact Display Form</H3>
</HEAD>
<BODY>
<!--METADATA TYPE="DesignerControl" startspan
<OBJECT ID="DataRangeHdr1" WIDTH=151 HEIGHT=24
CLASSID="CLSID:F602E721-A281-11CF-A5B7-0080C73AAC7E">
<PARAM NAME="_Version" VALUE="65536">
<PARAM NAME="_Version" VALUE="65536">
<PARAM NAME="_ExtentX" VALUE="3986">
<PARAM NAME="_ExtentY" VALUE="635">
<PARAM NAME="_StockProps" VALUE="0">
<PARAM NAME="DataConnection" VALUE="pubs">
<PARAM NAME="CommandText" VALUE="SELECT au_fname, au_lname, phone, address, 
city, state, zip FROM authors">
<PARAM NAME="CursorType" VALUE="1">
<PARAM NAME="RangeType" VALUE="1">
<PARAM NAME="PageSize" VALUE="1">
</OBJECT>
-->
<%
fHideNavBar = False
fHideNumber = False
fHideRequery = False
fHideRule = False
stQueryString = ""
fEmptyRecordset = False
fFirstPass = True
fNeedRecordset = False
fNoRecordset = False
tBarAlignment = "Left"
tHeaderName = "DataRangeHdr1"
tPageSize = 1
tPagingMove = ""
tRangeType = "Form"
tRecordsProcessed = 0

If Not IsEmpty(Request("DataRangeHdr1_PagingMove")) Then
tPagingMove = Trim(Request("DataRangeHdr1_PagingMove"))
End If
If IsEmpty(Session("DataRangeHdr1_Recordset")) Then
fNeedRecordset = True
Else
If Session("DataRangeHdr1_Recordset") Is Nothing Then
fNeedRecordset = True
Else
Set DataRangeHdr1 = Session("DataRangeHdr1_Recordset")
End If
End If
If fNeedRecordset Then
Set pubs = Server.CreateObject("ADODB.Connection")
pubs.ConnectionTimeout = Session("pubs_ConnectionTimeout")
pubs.CommandTimeout = Session("pubs_CommandTimeout")
pubs.Open Session("pubs_ConnectionString"), Session("pubs_RuntimeUserName"), Session("pubs_RuntimePassword")
Set cmdTemp = Server.CreateObject("ADODB.Command")
Set DataRangeHdr1 = Server.CreateObject("ADODB.Recordset")
cmdTemp.CommandText = "SELECT au_fname, au_lname, phone, address, city, state, 
zip FROM authors"
cmdTemp.CommandType = 1
Set cmdTemp.ActiveConnection = pubs
DataRangeHdr1.Open cmdTemp, , 1, 1
End If
On Error Resume Next
If DataRangeHdr1.BOF And DataRangeHdr1.EOF Then fEmptyRecordset = True
On Error Goto 0
If Err Then fEmptyRecordset = True
DataRangeHdr1.PageSize = tPageSize
If Not IsEmpty(Session("DataRangeHdr1_Filter")) And Not fEmptyRecordset Then
DataRangeHdr1.Filter = Session("DataRangeHdr1_Filter")
If DataRangeHdr1.BOF And DataRangeHdr1.EOF Then fEmptyRecordset = True
End If
If IsEmpty(Session("DataRangeHdr1_PageSize")) Then Session("DataRangeHdr1_
PageSize") = tPageSize
If IsEmpty(Session("DataRangeHdr1_AbsolutePage")) Then Session("DataRangeHdr1_
AbsolutePage") = 1
If Session("DataRangeHdr1_PageSize") <> tPageSize Then
tCurRec = ((Session("DataRangeHdr1_AbsolutePage") - 1) * Session("DataRangeHdr1_
PageSize")) + 1
tNewPage = Int(tCurRec / tPageSize)
If tCurRec Mod tPageSize <> 0 Then
tNewPage = tNewPage + 1
End If
If tNewPage = 0 Then tNewPage = 1
Session("DataRangeHdr1_PageSize") = tPageSize
Session("DataRangeHdr1_AbsolutePage") = tNewPage
End If
If fEmptyRecordset Then
fHideNavBar = True
fHideRule = True
Else
Select Case tPagingMove
Case "Requery"
DataRangeHdr1.Requery
Case "<<"
Session("DataRangeHdr1_AbsolutePage") = 1
Case "<"
If Session("DataRangeHdr1_AbsolutePage") > 1 Then
Session("DataRangeHdr1_AbsolutePage") = Session Â("DataRangeHdr1_AbsolutePage") - 1
End If
Case ">"
If Not DataRangeHdr1.EOF Then
Session("DataRangeHdr1_AbsolutePage") = Session Â("DataRangeHdr1_AbsolutePage") + 1
End If
Case ">>"
Session("DataRangeHdr1_AbsolutePage") = DataRangeHdr1.PageCount
End Select
DataRangeHdr1.AbsolutePage = Session("DataRangeHdr1_AbsolutePage")
If DataRangeHdr1.EOF Then
Session("DataRangeHdr1_AbsolutePage") = Session Â("DataRangeHdr1_AbsolutePage") - 1
DataRangeHdr1.AbsolutePage = Session("DataRangeHdr1_AbsolutePage")
End If
End If
Do
If fEmptyRecordset Then Exit Do
If tRecordsProcessed = tPageSize Then Exit Do
If Not fFirstPass Then
DataRangeHdr1.MoveNext
Else
fFirstPass = False
End If
If DataRangeHdr1.EOF Then Exit Do
tRecordsProcessed = tRecordsProcessed + 1
%>
<!--METADATA TYPE="DesignerControl" endspan-->
<INPUT TYPE="Text" SIZE=25 MAXLENGTH=20 NAME=au_fname 
VALUE="<%= DataRangeHdr1("au_fname") %>"><br>
<INPUT TYPE="Text" SIZE=25 MAXLENGTH=40 NAME=au_lname 
VALUE="<%= DataRangeHdr1("au_lname") %>"><br>
<INPUT TYPE="Text" SIZE=25 MAXLENGTH=40 NAME=address 
VALUE="<%= DataRangeHdr1("address") %>"><br>
<INPUT TYPE="Text" SIZE=25 MAXLENGTH=20 NAME=city 
VALUE="<%= DataRangeHdr1("city") %>"><br>
<INPUT TYPE="Text" SIZE=25 MAXLENGTH=2 NAME=state 
VALUE="<%= DataRangeHdr1("state") %>"><br>
<INPUT TYPE="Text" SIZE=25 MAXLENGTH=5 NAME=zip 
VALUE="<%= DataRangeHdr1("zip") %>"><br>
<INPUT TYPE="Text" SIZE=25 MAXLENGTH=12 NAME=phone 
VALUE="<%= DataRangeHdr1("phone") %>"><br>
<!--METADATA TYPE="DesignerControl" startspan
<OBJECT ID="DataRangeFtr1" WIDTH=151 HEIGHT=24
CLASSID="CLSID:F602E722-A281-11CF-A5B7-0080C73AAC7E">
<PARAM NAME="_Version" VALUE="65536">
<PARAM NAME="_ExtentX" VALUE="3969">
<PARAM NAME="_ExtentY" VALUE="635">
<PARAM NAME="_StockProps" VALUE="0">
</OBJECT>
-->
<%
Loop
If tRangeType = "Table" Then Response.Write "</TABLE>"
If tPageSize > 0 Then
If Not fHideRule Then Response.Write "<HR>"
If Not fHideNavBar Then
%>
<TABLE WIDTH=100% >
<TR>
<TD WIDTH=100% >
<P ALIGN=<%= tBarAlignment %> >
<FORM ACTION="<%= Request.ServerVariables("PATH_INFO") & 
stQueryString %>" METHOD="POST">
<INPUT TYPE="Submit" NAME="<%= tHeaderName & "_PagingMove" %>" 
VALUE="   &lt;&lt;   ">
<INPUT TYPE="Submit" NAME="<%= tHeaderName & "_PagingMove" %>" 
VALUE="   &lt;    ">
<INPUT TYPE="Submit" NAME="<%= tHeaderName & "_PagingMove" %>" 
VALUE="    &gt;   ">
<INPUT TYPE="Submit" NAME="<%= tHeaderName & "_PagingMove" %>" 
VALUE="   &gt;&gt;   ">
<% If Not fHideRequery Then %>
<INPUT TYPE="Submit" NAME="<% =tHeaderName & "_PagingMove" %>" 
VALUE=" Requery ">
<% End If %>
</FORM>
</P>
</TD>
<TD VALIGN=MIDDLE ALIGN=RIGHT>
<FONT SIZE=2>
<%
If Not fHideNumber Then
If tPageSize > 1 Then
Response.Write "<NOBR>Page: " & Session(tHeaderName & "_AbsolutePage") & 
"</NOBR>"
Else
Response.Write "<NOBR>Record: " & Session(tHeaderName & "_AbsolutePage") & 
"</NOBR>"
End If
End If
%>
</FONT>
</TD>
</TR>
</TABLE>
<%
End If
End If
%>
<!--METADATA TYPE="DesignerControl" endspan-->
</BODY>
</HTML>

Notice that the fields that are copied into the ASP file use the <INPUT> tags to create the display fields for the database information. The Data Range Header design-time control handles this formatting for you based on the Range Type that you select. This feature saves you precious development time. Figure 14.23 displays the form that is created from Listing 14.5.

Figure 14.23.

Displaying a form.

You could enhance the look of the form by adding additional line breaks or moving the fields around on the form. Listing 14.5, as well as the previous listings, demonstrates how you can rapidly build an application that interacts with your database information. Through the use of design-time controls, Visual InterDev takes care of the routine programming. The time that you save can be spent on enhancing the design of the web page and fine-tuning the programming logic.

Summary

ToChapter's lesson has introduced you to the exciting new world of design-time controls. These new controls combine raw power with ease-of-use to become a true friend of the developer. Design-time controls can truly augment your productivity. You can use design-time controls to provide rich and robust functionality in your application while reducing the overhead costs of your application.

In toChapter's lesson you first learned the definition of a design-time control. You should now be able to describe the basic concept of a design-time control, and be able to distinguish between a Design-time ActiveX control and a regular ActiveX control.

The lesson provided you with an overview of the origins of design-time controls and described some common functions of these controls. The lesson then guided you through the process of inserting a design-time control into your web pages. You learned about three specific design-time controls that are included with Visual InterDev. First, you learned how to use the Data Command design-time control. The lesson explained each of the property pages for this control and how to set these properties. The lesson also taught you about common uses of this control. Next, you learned about the Data Range Header and Data Range Footer controls. You discovered how these two controls complement and complete each other.

You also learned how the Query Designer can be used with all of the database design-time controls. Toward the end of the Chapter, the lesson explained how to use the Data Range Builder Wizard. You can use this wizard to easily insert pairs of design-time controls into your web page documents at one time. The final lesson for the Chapter focused on using the Data Range Header and Footer controls to create a display form for your database information.

You have just completed the second week of your Visual InterDev training. How do you feel so far about the product? Hopefully, the first two weeks have given you a good overall look at using the features of Visual InterDev. You should now possess a solid foundation with which to build robust applications with Visual InterDev. The final week teaches you some additional advanced concepts that you can use to build your applications.

Q&A

Q Can I build my own custom design-time controls?


A
Yes. In fact, you will learn how to build a design-time control on Chapter 16, "Building Design-Time ActiveX Controls."


Q How does the design-time control hide its object instantiation at run-time


A
A design-time control is created at the time of design, using the <OBJECT> tags. These tags primarily exist to enable you to edit the properties for the control using the visual Object Editor. The <OBJECT> tags are enclosed in comments, however, which prevents the browser from viewing or recognizing the object. For this reason, the object is never instantiated at runtime.


Q If the object is never instantiated, how does the design-time control accomplish its functionality


A
The properties that you define for the design-time control generate runtime code, which persists when the application is run. This code can be a combination of both HTML and scripting code and represents all of the logic for the design-time control. When the user runs the application, this code is recognized and executed, thereby providing the functionality of the design-time control.

Workshop

I want you to extend the examples that were provided in toChapter's lesson. The goal is to gain extra practice using design-time controls within your application. Using the table example and the display form, develop an application that integrates the two forms. You also should develop additional functionality that enables you to submit updates and additions of new authors to the database. Draw on all of the knowledge that you have gained in the first two weeks to complete this workshop. If you aren't using MS SQL Server as your database, you can still plug in your specific database and apply the concepts to build an application.

Quiz

1. What is the difference between Design-time and regular ActiveX controls?


2.
Explain the difference between the Data Command and the Data Range controls.


3
Which feature enables you to easily format the values of the database fields into a web page document?


4
Name the three types of data ranges that can be created for a Data Range Header design-time control.

Quiz Answers

1. A design-time control is a special type of ActiveX control that provides code that persists and executes at runtime without incurring the overhead of a control object at runtime. Regular ActiveX controls exist both at design-time as well as at runtime. ActiveX controls are typically used to construct a user interface for your application. An ActiveX control object is instantiated at runtime.


2.
The Data Command design-time control enables you to create a database connection and a Recordset object which you can use to query the database. The Data Command control is typically used for selecting and updating one database row at a time. The Data Range design-time controls are similar to the Data Command control in that they also create a database connection and Recordset object. The Data Range controls differ in that they typically are used for publishing and modifying multiple rows of data. The Data Range controls enable you to traverse through multiple records in the database.


3
You can use the Copy Fields dialog window to select database fields to insert into the web page document. This feature enables you to display the information contained in your database.


4
The three Range Types for the Data Range Header design-time control include:

Text
Form
Table

BACKFORWARDTOC





|  About us | Categories | New Releases | Most Popular | Web Tutorial | Free Download | Drivers |



2013 Soft Lookup Corp. Privacy Statement