IWebPartTable.GetTableData(TableCallback) Method

Definition

Namespace:

System.Web.UI.WebControls.WebParts

Assembly:

System.Web.dll

Returns the data for the table that is being used by the interface as the basis of a connection between two WebPart controls.

public:
 void GetTableData(System::Web::UI::WebControls::WebParts::TableCallback ^ callback);

public void GetTableData (System.Web.UI.WebControls.WebParts.TableCallback callback);

abstract member GetTableData : System.Web.UI.WebControls.WebParts.TableCallback -> unit

Public Sub GetTableData (callback As TableCallback)

Parameters

callback

TableCallback

A TableCallback delegate that contains the address of a method that receives the data.

Examples

The following code example shows the implementation and use of the GetTableData method. The complete example is shown in the class overview for the IWebPartTable interface. The provider control implements the GetTableData method, returning the data in the specified table. The consumer control calls the GetTableData method in its OnPreRender method, so that the value of the data can be written to the page.

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

Remarks

Use this method to retrieve the data table values passed by the interface. The provider implements this method, and the consumer invokes it at the point when the consumer is ready to process or render data.