IWebPartRow.Schema Property
Gets the schema information for a data row that is used to share data between two WebPart controls.
Assembly: System.Web (in System.Web.dll)
Property Value
Type: System.ComponentModel.PropertyDescriptorCollectionA PropertyDescriptorCollection describing the data.
This property provides property information for the data. Using the IWebPartRow interface in a connection, you get a PropertyDescriptorCollection object, which is referenced by the Schema property. The contract specifies that calling Schema[n].GetValue(RowData) returns the value of the nth column in the row. You need to use the Schema property to get the values in the row.
The following code example shows the implementation and use of the Schema property. The complete example is shown in the class overview for the IWebPartRow interface. The provider control implements the Schema property. Then the consumer control, in its RenderContents method, queries the Schema property to retrieve information about the row as it writes the row data to the page.
Imports System 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 row data. <AspNetHostingPermission(SecurityAction.Demand, _ Level:=AspNetHostingPermissionLevel.Minimal)> _ <AspNetHostingPermission(SecurityAction.InheritanceDemand, _ Level:=AspNetHostingPermissionLevel.Minimal)> _ Public NotInheritable Class RowProviderWebPart Inherits WebPart Implements IWebPartRow 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 'NewNew <ConnectionProvider("Row")> _ Public Function GetConnectionInterface() As IWebPartRow Return New RowProviderWebPart() End Function 'GetConnectionInterface Public ReadOnly Property Schema() As _ ComponentModel.PropertyDescriptorCollection Implements IWebPartRow.Schema Get Return TypeDescriptor.GetProperties(_table.DefaultView(0)) End Get End Property Public Sub GetRowData(ByVal callback As RowCallback) _ Implements IWebPartRow.GetRowData callback(_table.Rows) End Sub End Class 'RowProviderWebPart ' This sample code creates a Web Parts control that acts as a consumer ' of row data. <AspNetHostingPermission(SecurityAction.Demand, _ Level:=AspNetHostingPermissionLevel.Minimal)> _ <AspNetHostingPermission(SecurityAction.InheritanceDemand, _ Level:=AspNetHostingPermissionLevel.Minimal)> _ Public NotInheritable Class RowConsumerWebPart Inherits WebPart Private _provider As IWebPartRow Private _tableData As ICollection Private Sub GetRowData(ByVal rowData As Object) _tableData = CType(rowData, ICollection) End Sub Protected Overrides Sub OnPreRender(ByVal e As EventArgs) If Not (_provider Is Nothing) Then _provider.GetRowData(New RowCallback(AddressOf GetRowData)) 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)) writer.WriteBreak() writer.WriteLine() count = count + 1 Next o Next prop Else writer.Write("No data") End If Else writer.Write("Not connected") End If End Sub <ConnectionConsumer("Row")> _ Public Sub SetConnectionInterface(ByVal provider As IWebPartRow) _provider = provider End Sub End Class 'RowConsumerWebPart End Namespace ' Samples.AspNet.VB.Controls
Available since 2.0