TableCallback Delegate
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References the method to call when retrieving table data from a provider.
public delegate void TableCallback(ICollection ^ tableData);
public delegate void TableCallback(ICollection tableData);
type TableCallback = delegate of ICollection -> unit
Public Delegate Sub TableCallback(tableData As ICollection)
- tableData
- ICollection
The data to retrieve from the provider.
The following code example contains a Web Parts control named TableProviderWebPart
that serves as a provider of data in the form of a table. The control includes an implementation of the GetTableData method, which receives a parameter of type TableCallback. This method calls the method represented by the TableCallback delegate passing the table data.
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Reflection;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
//This sample code creates a Web Parts control that acts as a provider of table data.
namespace Samples.AspNet.CS.Controls
{
public sealed class TableProviderWebPart : WebPart, IWebPartTable
{
DataTable _table;
public TableProviderWebPart()
{
_table = new DataTable();
DataColumn col = new DataColumn();
col.DataType = typeof(string);
col.ColumnName = "Name";
_table.Columns.Add(col);
col = new DataColumn();
col.DataType = typeof(string);
col.ColumnName = "Address";
_table.Columns.Add(col);
col = new DataColumn();
col.DataType = typeof(int);
col.ColumnName = "ZIP Code";
_table.Columns.Add(col);
DataRow row = _table.NewRow();
row["Name"] = "John Q. Public";
row["Address"] = "123 Main Street";
row["ZIP Code"] = 98000;
_table.Rows.Add(row);
}
public PropertyDescriptorCollection Schema
{
get
{
return TypeDescriptor.GetProperties(_table.DefaultView[0]);
}
}
public void GetTableData(TableCallback callback)
{
callback(_table.Rows);
}
public bool ConnectionPointEnabled
{
get
{
object o = ViewState["ConnectionPointEnabled"];
return (o != null) ? (bool)o : true;
}
set
{
ViewState["ConnectionPointEnabled"] = value;
}
}
[ConnectionProvider("Table")]
public IWebPartTable GetConnectionInterface()
{
return new TableProviderWebPart();
}
public class TableProviderConnectionPoint : ProviderConnectionPoint
{
public TableProviderConnectionPoint(MethodInfo callbackMethod,
Type interfaceType, Type controlType,
string name, string id, bool allowsMultipleConnections)
: base(callbackMethod, interfaceType, controlType,
name, id, allowsMultipleConnections)
{
}
public override bool GetEnabled(Control control)
{
return ((TableProviderWebPart)control).ConnectionPointEnabled;
}
}
}
}
Imports System.Collections
Imports System.ComponentModel
Imports System.Data
Imports System.Reflection
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
'This sample code creates a Web Parts control that acts as a provider of table data.
Namespace Samples.AspNet.VB.Controls
Public NotInheritable Class TableProviderWebPart
Inherits WebPart
Implements IWebPartTable
Private _table As DataTable
Public Sub New()
_table = New DataTable()
Dim col As New DataColumn()
col.DataType = GetType(String)
col.ColumnName = "Name"
_table.Columns.Add(col)
col = New DataColumn()
col.DataType = GetType(String)
col.ColumnName = "Address"
_table.Columns.Add(col)
col = New DataColumn()
col.DataType = GetType(Integer)
col.ColumnName = "ZIP Code"
_table.Columns.Add(col)
Dim row As DataRow = _table.NewRow()
row("Name") = "John Q. Public"
row("Address") = "123 Main Street"
row("ZIP Code") = 98000
_table.Rows.Add(row)
End Sub
<ConnectionProvider("Table")> _
Public Function GetConnectionInterface() As IWebPartTable
Return New TableProviderWebPart()
End Function 'GetConnectionInterface
Public ReadOnly Property Schema() As PropertyDescriptorCollection _
Implements IWebPartTable.Schema
Get
Return TypeDescriptor.GetProperties(_table.DefaultView(0))
End Get
End Property
Public Property ConnectionPointEnabled() As Boolean
Get
Dim o As Object
o = ViewState("ConnectionPointEnabled")
If Not (o Is Nothing) Then
Return CBool(o)
Else
Return True
End If
End Get
Set(ByVal value As Boolean)
ViewState("ConnectionPointEnabled") = value
End Set
End Property
Public Sub GetTableData(ByVal callback As TableCallback) _
Implements IWebPartTable.GetTableData
callback(_table.Rows)
End Sub
End Class
End Namespace
In the OnPreRender
method, the consumer calls GetTableData
in TableProviderWebPart
and passes its GetTableData
method as the delegate to call with the table data, as shown in the following code example.
namespace Samples.AspNet.CS.Controls
{
using System;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Reflection;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Collections;
public class TableConsumer : WebPart
{
private IWebPartTable _provider;
private ICollection _tableData;
private void GetTableData(object tableData)
{
_tableData = (ICollection)tableData;
}
protected override void OnPreRender(EventArgs e)
{
if (_provider != null)
{
_provider.GetTableData(new TableCallback(GetTableData));
}
}
protected override void RenderContents(HtmlTextWriter writer)
{
if (_provider != null)
{
PropertyDescriptorCollection props = _provider.Schema;
int count = 0;
if (props != null && props.Count > 0 && _tableData != null)
{
foreach (PropertyDescriptor prop in props)
{
foreach (DataRow o in _tableData)
{
writer.Write(prop.DisplayName + ": " + o[count]);
}
writer.WriteBreak();
writer.WriteLine();
count = count + 1;
}
}
else
{
writer.Write("No data");
}
}
else
{
writer.Write("Not connected");
}
}
[ConnectionConsumer("Table")]
public void SetConnectionInterface(IWebPartTable provider)
{
_provider = provider;
}
}
}
Imports System.ComponentModel
Imports System.Reflection
Imports System.Collections
Imports System.Data
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Namespace Samples.AspNet.VB.Controls
Public Class TableConsumerWebPart
Inherits WebPart
Private _provider As IWebPartTable
Private _tableData As ICollection
Private Sub GetTableData(ByVal tableData As ICollection)
_tableData = CType(tableData, ICollection)
End Sub
Protected Overrides Sub OnPreRender(ByVal e As EventArgs)
If Not (_provider Is Nothing) Then
_provider.GetTableData((New TableCallback(AddressOf GetTableData)))
End If
'MyBase.OnPreRender(e)
End Sub
Protected Overrides Sub RenderContents(ByVal writer As HtmlTextWriter)
If Not (_provider Is Nothing) Then
Dim props As PropertyDescriptorCollection = _provider.Schema
Dim count As Integer = 0
If Not (props Is Nothing) AndAlso props.Count > 0 _
AndAlso Not (_tableData Is Nothing) Then
For Each prop As PropertyDescriptor In props
For Each o As DataRow In _tableData
writer.Write(prop.DisplayName & ": " & o(count).ToString())
Next
writer.WriteBreak()
writer.WriteLine()
count = count + 1
Next
Else
writer.Write("No data")
End If
Else
writer.Write("Not connected")
End If
End Sub
<ConnectionConsumer("Table")> _
Public Sub SetConnectionInterface(ByVal provider As IWebPartTable)
_provider = provider
End Sub
Private Class TableConsumerConnectionPoint
Inherits ConsumerConnectionPoint
Public Sub New(ByVal callbackMethod As MethodInfo, _
ByVal interfaceType As Type, ByVal controlType As Type, _
ByVal name As String, ByVal id As String, _
ByVal allowsMultipleConnections As Boolean)
MyBase.New(callbackMethod, interfaceType, controlType, _
name, id, allowsMultipleConnections)
End Sub
End Class
End Class
End Namespace
The two controls and the connection are included in a Web page, as shown in the following example.
<%@ page language="C#" %>
<%@ Register tagprefix="wp" Namespace="Samples.AspNet.CS.Controls" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>ITable Test Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<!-- A static or dynamic connection is required to link two
Web Parts controls. --->
<asp:webpartmanager id="WebPartManager1" runat="server">
<StaticConnections>
<asp:WebPartConnection id="wp1" ProviderID="provider1"
ConsumerID="consumer1">
</asp:WebPartConnection>
</StaticConnections>
</asp:webpartmanager>
<asp:webpartzone id="WebPartZone1" runat="server">
<zoneTemplate>
<!-- The following two lines define the
two connected controls. --->
<wp:TableProviderWebPart ID="provider1" runat="server"
title="Web Parts Table Provider Control" />
<wp:TableConsumer ID="consumer1" runat="server"
title="Web Parts Table Consumer Control"/>
</zoneTemplate>
</asp:webpartzone>
</div>
</form>
</body>
</html>
<%@ Page Language="VB" %>
<%@ Register tagprefix="wp" Namespace="Samples.AspNet.VB.Controls" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>ITable Test Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<!-- A static or dynamic connection is required to
link two Web Parts controls. --->
<asp:webpartmanager id="WebPartManager1" runat="server">
<StaticConnections>
<asp:WebPartConnection id="wp1" ProviderID="provider1"
ConsumerID="consumer1">
</asp:WebPartConnection>
</StaticConnections>
</asp:webpartmanager>
<asp:webpartzone id="WebPartZone1" runat="server">
<zoneTemplate>
<!-- The following two lines define the two
connected controls. --->
<wp:TableProviderWebPart ID="provider1" runat="server"
title="Web Parts Table Provider Control" />
<wp:TableConsumerWebPart ID="consumer1" runat="server"
title="Web Parts Table Consumer Control"/>
</zoneTemplate>
</asp:webpartzone>
</div>
</form>
</body>
</html>
When a Web Parts control implements the IWebPartTable interface and serves as a provider in a Web Parts connection, the consumer or transformer must retrieve and process the table data from the provider. The TableCallback delegate represents the method to call for processing the provider data.
The GetTableData method contains a TableCallback delegate parameter.
Get |
Gets an object that represents the method represented by the specified delegate. |
Product | Versions |
---|---|
.NET Framework | 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
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