IWebPartTable Interface
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Defines a provider interface for connecting two server controls using an entire table of data.
public interface class IWebPartTablepublic interface IWebPartTabletype IWebPartTable = interfacePublic Interface IWebPartTableExamples
The following code example demonstrates how to create a static connection between two controls using the IWebPartTable interface. The code example has three parts:
Source code for two custom WebPart controls that can form a connection using the IWebPartTable interface, with one control acting as the provider and the other acting as the consumer.
A Web page that hosts the controls and declares the static connection in persistence format.
A description of what happens when the example code runs.
The first part of the code example is the source code for the two custom controls. First is the code for the provider, which implements the IWebPartTable interface. For simplicity in the example, the provider creates a table with some data rather than connecting to a database. The GetConnectionInterface method serves as the provider's connection point, the callback method that returns the interface instance to the consumer. As for the consumer, it retrieves the interface instance from the provider in its method named SetConnectionInterface, which is marked with a ConnectionConsumer attribute. After retrieving the instance of the interface, the consumer, in its OnPreRender method, calls the implementation of the GetTableData method in the provider, to retrieve the actual data and write it to the page.
For the code example to run, you must compile this source code. You can compile it explicitly and put the resulting assembly in your Web site's Bin folder or the global assembly cache. Alternatively, you can put the source code in your site's App_Code folder, where it will be dynamically compiled at run time. This code example uses dynamic compilation. For a walkthrough that demonstrates how to compile, see Walkthrough: Developing and Using a Custom Web Server Control.
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Reflection;
using System.Security.Permissions;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
namespace Samples.AspNet.CS.Controls
{
// This sample code creates a Web Parts control that acts as a provider
// of table data.
[AspNetHostingPermission(SecurityAction.Demand,
Level = AspNetHostingPermissionLevel.Minimal)]
[AspNetHostingPermission(SecurityAction.InheritanceDemand,
Level = AspNetHostingPermissionLevel.Minimal)]
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", typeof(TableProviderConnectionPoint),
AllowsMultipleConnections = true)]
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;
}
}
}
// This code sample creates a Web Parts control that acts as a consumer
// of information provided by the TableProvider.ascx control.
[AspNetHostingPermission(SecurityAction.Demand,
Level = AspNetHostingPermissionLevel.Minimal)]
[AspNetHostingPermission(SecurityAction.InheritanceDemand,
Level = AspNetHostingPermissionLevel.Minimal)]
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;
}
public class TableConsumerConnectionPoint : ConsumerConnectionPoint
{
public TableConsumerConnectionPoint(MethodInfo callbackMethod,
Type interfaceType, Type controlType, string name, string id,
bool allowsMultipleConnections)
: base(callbackMethod, interfaceType, controlType, name, id,
allowsMultipleConnections)
{
}
} // TableConsumerConnectionPoint
} // TableConsumer
} // Samples.AspNet.CS.Controls
Imports System.Collections
Imports System.ComponentModel
Imports System.Data
Imports System.Reflection
Imports System.Security.Permissions
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Namespace Samples.AspNet.VB.Controls
' This sample code creates a Web Parts control that acts as a provider
' of table data.
<AspNetHostingPermission(SecurityAction.Demand, _
Level:=AspNetHostingPermissionLevel.Minimal)> _
<AspNetHostingPermission(SecurityAction.InheritanceDemand, _
Level:=AspNetHostingPermissionLevel.Minimal)> _
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
Public ReadOnly Property Schema() As _
ComponentModel.PropertyDescriptorCollection Implements IWebPartTable.Schema
Get
Return TypeDescriptor.GetProperties(_table.DefaultView(0))
End Get
End Property
Public Sub GetTableData(ByVal callback As TableCallback) _
Implements IWebPartTable.GetTableData
callback(_table.Rows)
End Sub
Public Property ConnectionPointEnabled() As Boolean
Get
Dim o As Object = ViewState("ConnectionPointEnabled")
Return IIf(Not (o Is Nothing), CBool(o), True)
End Get
Set(ByVal value As Boolean)
ViewState("ConnectionPointEnabled") = value
End Set
End Property
<ConnectionProvider("Table", GetType(TableProviderConnectionPoint), _
AllowsMultipleConnections:=True)> _
Public Function GetConnectionInterface() As IWebPartTable
Return New TableProviderWebPart()
End Function
End Class
' The connection point for the provider control.
<AspNetHostingPermission(SecurityAction.Demand, _
Level:=AspNetHostingPermissionLevel.Minimal)> _
<AspNetHostingPermission(SecurityAction.InheritanceDemand, _
Level:=AspNetHostingPermissionLevel.Minimal)> _
Public Class TableProviderConnectionPoint
Inherits ProviderConnectionPoint
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
Public Overrides Function GetEnabled(ByVal control _
As Control) As Boolean
Return CType(control, TableProviderWebPart).ConnectionPointEnabled
End Function
End Class
' This code sample creates a Web Parts control that acts as a consumer
' of information provided by the TableProvider.ascx control.
<AspNetHostingPermission(SecurityAction.Demand, _
Level:=AspNetHostingPermissionLevel.Minimal)> _
<AspNetHostingPermission(SecurityAction.InheritanceDemand, _
Level:=AspNetHostingPermissionLevel.Minimal)> _
Public Class TableConsumer
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
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
Dim prop As PropertyDescriptor
For Each prop In props
Dim o As DataRow
For Each o In _tableData
writer.Write(prop.DisplayName & ": " & o(count))
Next o
writer.WriteBreak()
writer.WriteLine()
count = count + 1
Next prop
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
End Class
' The connection point for the consumer control.
<AspNetHostingPermission(SecurityAction.Demand, _
Level:=AspNetHostingPermissionLevel.Minimal)> _
<AspNetHostingPermission(SecurityAction.InheritanceDemand, _
Level:=AspNetHostingPermissionLevel.Minimal)> _
Public 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 Namespace ' Samples.AspNet.CS.Controls
The second part of the code example is the Web page that declares the static connection and hosts the controls. Near the top of the page is a Register directive that declares the namespace of the source code contained in the App_Code directory. The connection is declared using an <asp:webpartconnection> element. The custom consumer and provider controls are declared in a <zonetemplate> element within an <asp:webpartzone> element, which is required for them to be able to connect (they must reside within a zone that inherits from the WebPartZoneBase class).
<%@ page language="C#" %>
<%@ Register tagprefix="IRow"
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">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>IRow Test Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<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>
<irow:RowProviderWebPart ID="provider1" runat="server"
Title="Row Provider Control" />
<irow:RowConsumerWebPart ID="consumer1" runat="server"
Title="Row Consumer Control" />
</ZoneTemplate>
</asp:webpartzone>
</div>
</form>
</body>
</html>
<%@ page language="VB" %>
<%@ Register tagprefix="IRow"
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">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>IRow Test Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<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>
<irow:RowProviderWebPart ID="provider1" runat="server"
Title="Row Provider Control" />
<irow:RowConsumerWebPart ID="consumer1" runat="server"
Title="Row Consumer Control" />
</ZoneTemplate>
</asp:webpartzone>
</div>
</form>
</body>
</html>
Load the page in a browser. The consumer control displays the data provided from the specified table, which the provider makes available through an instance of the IWebPartTable interface.
Remarks
This interface is designed to be used with Web Parts connections. In a Web Parts connection, two server controls that reside in a WebPartZoneBase zone establish a connection and share data, with one control acting as the consumer and the other control acting as a provider. The mechanism for sharing data in a Web Parts connection is an interface instance, which the provider serves to the consumer by means of a callback method. To establish a connection, the consumer and provider must both work with the same interface type for sharing data. If the consumer does not recognize the interface type sent by the provider, it is still possible to connect the controls by means of a transformer (a WebPartTransformer object) that translates the interface instance sent by the provider into a type that the consumer recognizes. For details on connections, see WebPartConnection and Web Parts Connections Overview.
The IWebPartTable interface is a provider interface included with the Web Parts control set as a standard interface for creating connections based on a data table. You can also create custom interfaces to use with Web Parts connections, but in many data-driven Web applications, it is useful to create connections based on a common field (for details, see the IWebPartField interface), row (for details, see the IWebPartRow interface), or table from the data source. In a typical connection, a WebPart control acting as a provider would implement the IWebPartTable interface and provide an instance of the interface to consumers in a special callback method. For example, the provider might implement an IWebPartTable interface for a table that contains financial performance data. Another WebPart control acting as a consumer would define a special method to receive the interface instance, and could then extract the data and render a chart to display the resulting information.
The IWebPartTable interface has two exposed members. The Schema property returns schema information about the data table encapsulated in a PropertyDescriptorCollection object. The GetTableData method declares a method that an implementer (such as a provider control) uses to retrieve the interface instance's table data when the callback method is invoked.
Properties
| Schema |
Gets the schema information for a data table that is used to share data between two WebPart controls. |
Methods
| GetTableData(TableCallback) |
Returns the data for the table that is being used by the interface as the basis of a connection between two WebPart controls. |
