The GridView, DetailsView, and FormView are new additions under the .NET 2.0 framework and are likely to become the workhorses for delivery of information from external data sources. Under earlier versions, three other bindable controls were used: <asp:Repeater>, <asp:DataList>, and <asp:DataGrid>. These controls still have a place in ASP.NET 2.0, although most of their functionality has been absorbed by the newer controls. You are also likely to encounter them on existing Web pages that have not been transitioned to the new environment. Each of these controls are briefly covered in the following tutorials.

An <asp:Repeater> control displays a repeated list of data items that are bound to it. Like the GridView, it is designed for convenient display of records from a database or other relational data source.

The Repeater control is based on the use of templates, models for output display using binding expressions, server controls, and XHTML tags to structure the output. Its use is very similar to that of a FormView or a TemplateField in a GridView. The general format for coding a Repeater is shown below. Not all sections of the control are needed to produce simple data listings.

<asp:Repeater id="id" Runat="Server"
  DataSourceID="id">
		
  <HeaderTemplate>
    XHTML and binding expressions
  </HeaderTemplate>
	 
  <ItemTemplate>
    XHTML and binding expressions
  </ItemTemplate>
	  
    <AlternatingItemTemplate>
      XHTML and binding expressions
    </AlternatingItemTemplate>
	 
    <SeparatorTemplate>
      XHTML and binding expressions
    </SeparatorTemplate>
			
  <FooterTemplate>
    XHTML and binding expressions
  </FooterTemplate>


</asp:Repeater>

Binding to a Repeater Control

A Repeater is bound to a data source to display its contents. As in the case of a GridView, a Repeater can be linked to a data source control such as an AccessDataSource. As in the case of using TemplateField columns in a GridView, data fields are bound to the Repeater through individual data field binding expressions.

In its simplest format, the Repeater requires only an <Item Template> to describe its output format. Within this template, text, XHTML, and binding expressions are coded to provide a model for formatting the data. In the following example, output is formatted as repeating lines of data, each line composed of selected data fields from the Books table of the BooksDB.mdb database.

<asp:AccessDataSource id="BookSource" Runat="Server"
  DataFile="../Databases/BooksDB.mdb"
  SelectCommand="SELECT * FROM Books ORDER BY BookID"/>
	
<asp:Repeater id="BookTable" DataSourceID="BookSource" Runat="Server">
  <ItemTemplate>
    <%# Eval("BookID") %>, 
    <%# Eval("BookTitle") %>, 
    <%# String.Format("{0:C}", Eval("BookPrice")) %><br/>
  </ItemTemplate>
</asp:Repeater>

The <ItemTemplate> section of the control specifies the data items to be displayed along with any XHTML formatting for the data. This template is a model for a single output line, and when data are bound to the Repeater the template is repeated for as many records as appear in the recordset.

Data displays inside an ItemTemplate are given by binding expressions in the same format used for other template-based controls.

<%# Eval("fieldname") %>

The fieldname is the name of a field from the data source whose value is displayed. In the above example, three data fields—BookID , BookTitle, and BookPrice—are extracted to display all records in the Books table. Note that data binding can take place only in the <ItemTemplate>, not in the <HeaderTemplate> or <FooterTemplate> sections of the Repeater.

Although these simple binding expressions can work for a Repeater, it is more conventional to bind output to server controls to take advantage of styling properties of the controls. An alternative to coding the above Repeater is shown below using Label controls as display areas with output bound to the Text properties of the controls.

<asp:Repeater id="BookTable" DataSourceID="BookSource" Runat="Server">
  <ItemTemplate>
    <asp:Label Text='<%# Eval("ItemNumber") %>' Runat="Server"/>, 
    <asp:Label Text='<%# Eval("ItemName") %>' Runat="Server"/>, 
    <asp:Label Text='<%# String.Format("{0:C}", Eval("BookPrice")) %>' 
      Runat="Server"/><br/>
  </ItemTemplate>
</asp:Repeater>

Formatting a Repeater as a Table

There can be three sections of Repeater output described within <HeaderTemplate>, <ItemTemplate>, and <FooterTemplate> sections of the control. The HeaderTemplate appears one time at the beginning of output; the ItemTemplate is repeated for as many records as there are in the bound data source; the FooterTemplate appears one time at the close of output. These three sections are ideally suited for displaying output within a table format.

<SCRIPT Runat="Server">

Function Get_Amount (Price As Decimal, Quantity As Integer)

  Dim Amount As Decimal = Price * Quantity
  Return String.Format("{0:#,0.00}", Amount)
	
End Function

</SCRIPT>

<form Runat="Server">

<asp:AccessDataSource id="BookSource" Runat="Server"
  DataFile="../Databases/BooksDB.mdb"
  SelectCommand="SELECT * FROM Books ORDER BY BookID"/>
	
<asp:Repeater id="BookTable" DataSourceID="BookSource" Runat="Server">
  <HeaderTemplate>
    <table border="1" cellpadding="1" style="border-collapse:collapse">
    <caption style="font-weight:bold">Book Listing</caption>
    <tr style="background-color:#707070; color:#FFFFFF">
      <th>ID</th>
      <th>Title</th>
      <th>Price</th>
      <th>Qty</th>
      <th>Amount</th>
    </tr>
  </HeaderTemplate>
  <ItemTemplate>
    <tr>
      <td><asp:Label Text='<%# Eval("BookID") %>' Runat="Server"/></td>
      <td><asp:Label Text='<%# Eval("BookTitle") %>' Runat="Server"/></td>
      <td style="text-align:right">
        <asp:Label Text='<%# String.Format("{0:N}", Eval("BookPrice")) %>' 
          Runat="Server"/></td>
      <td style="text-align:right">
        <asp:Label Text='<%# String.Format("{0:D}", Eval("BookQty")) %>' 
          Runat="Server"/></td>
      <td style="text-align:right">
        <asp:Label Text='<%# Get_Amount(Eval("BookPrice"), Eval("BookQty")) %>' 
          Runat="Server"/></td>
    </tr>
  </ItemTemplate>
  <FooterTemplate>
    <tr style="background-color:#707070; color:#FFFFFF">
      <td colspan="5" style="font-size:10pt; font-style:italic">
        Source: Books table
      </td>
    </tr>
   </table>
  </FooterTemplate>
</asp:Repeater>

</form>

The <HeaderTemplate> contains HTML code to define a table and describe its column headings, which are displayed once within the output. The <ItemTemplate> contains code to describe a table row that is repeated once for each record in the recordset. The <FooterTemplate> contains code for the closing table tags that appear once at the end of output.

The BookPrice and BookQty values for a row are passed to function Get_Amount where the amount is calculated and formatted with a custom format string for return to the calling statement for display.

Other Templates

An <AlternatingItemTemplate> can be coded following the <ItemTemplate> to decribe the appearance of alternating rows of output. The AlternatingItemTemplate is a repeating template that can contain different data items from the ItemTemplate. A <SeparatorTemplate> can be coded to describe a separator line between each detail line of display. In the following example, an AlternatingItemTemplate is added to the previous Repeater to produce alternating row shadings.

<SCRIPT Runat="Server">

Function Get_Amount (Price As Decimal, Quantity As Integer)

  Dim Amount As Decimal = Price * Quantity
  Return String.Format("{0:#,0.00}", Amount)
	
End Function

</SCRIPT>

<form Runat="Server">

<asp:AccessDataSource id="BookSource" Runat="Server"
  DataFile="../Databases/BooksDB.mdb"
  SelectCommand="SELECT * FROM Books ORDER BY BookID"/>
	
<asp:Repeater id="BookTable" DataSourceID="BookSource" Runat="Server">
  <HeaderTemplate>
    <table border="0" cellpadding="1">
    <caption style="font-weight:bold">Book Listing</caption>
    <tr style="background-color:#707070; color:#FFFFFF">
      <th>ID</th>
      <th>Title</th>
      <th>Price</th>
      <th>Qty</th>
      <th>Amount</th>
    </tr>
  </HeaderTemplate>
  <ItemTemplate>
    <tr>
      <td><asp:Label Text='<%# Eval("BookID") %>' Runat="Server"/></td>
      <td><asp:Label Text='<%# Eval("BookTitle") %>' Runat="Server"/></td>
      <td style="text-align:right">
        <asp:Label Text='<%# String.Format("{0:N}", Eval("BookPrice")) %>' 
          Runat="Server"/></td>
      <td style="text-align:right">
        <asp:Label Text='<%# String.Format("{0:D}", Eval("BookQty")) %>' 
          Runat="Server"/></td>
      <td style="text-align:right">
        <asp:Label Text='<%# Get_Amount(Eval("BookPrice"), Eval("BookQty")) %>' 
          Runat="Server"/></td>
    </tr>
  </ItemTemplate>
  <AlternatingItemTemplate>
    <tr style="background-color:#A0A0A0; color:#FFFFFF">
      <td><asp:Label Text='<%# Eval("BookID") %>' Runat="Server"/></td>
      <td><asp:Label Text='<%# Eval("BookTitle") %>' Runat="Server"/></td>
      <td style="text-align:right">
        <asp:Label Text='<%# String.Format("{0:N}", Eval("BookPrice")) %>' 
          Runat="Server"/></td>
      <td style="text-align:right">
        <asp:Label Text='<%# String.Format("{0:D}", Eval("BookQty")) %>' 
          Runat="Server"/></td>
      <td style="text-align:right">
        <asp:Label Text='<%# Get_Amount(Eval("BookPrice"), Eval("Bookqty")) %>' 
          Runat="Server"/></td>
    </tr>
  </AlternatingItemTemplate>
  <FooterTemplate>
    <tr style="background-color:#707070; color:#FFFFFF">
      <td colspan="5" style="font-size:10pt; font-style:italic">
        Source: Books table
      </td>
    </tr>
   </table>
  </FooterTemplate>
</asp:Repeater>

</form>

The <asp:Repeater> control provides great flexibility in formatting output from a bound data source. Virtually any XHTML tags and server controls can be added to the templates to arrange and style the data items. You will probably favor this control if you prefer, or if you don't mind, coding XHTML to produce your output.

A Repeater does not provide automatic sorting as do the GridView, DetailsView, and FormView controls. This feature must be scripted. Sorting records for a Repeater is discussed under the topic "Displaying Sorted Records." Neither does a Repeater offer built-in ways of paging output. You would need to write special script to cause this to happen.