WebPartConnection.Consumer Property
Gets a WebPart object that is acting as the consumer control in a connection.
Assembly: System.Web (in System.Web.dll)
| Exception | Condition |
|---|---|
| InvalidOperationException | The length of the ConsumerID property is zero. |
Every Web Parts connection consists of two controls that share data. One control acts as the provider of data, and the other control acts as a consumer, receiving and processing the data from the provider. The Consumer property gets a reference to the WebPart control acting as a consumer in a connection relationship.
The following code example demonstrates the programmatic use of the Consumer property.
The code example has four parts:
A user control that enables you to change the Web Parts display mode on a page.
Source code for an interface and two WebPart controls acting as the provider and the consumer for a connection.
A Web page to host all the controls and run the code example.
An explanation of how to run the example page.
The first part of this code example is the user control that enables users to change display modes on a Web page. Save the following source code to an .ascx file, giving it the file name that is assigned to the Src attribute of the Register directive for this user control, which is near the top of the hosting Web page. For details about display modes and a description of the source code in this control, see Walkthrough: Changing Display Modes on a Web Parts Page.
<%@ control language="vb" classname="DisplayModeMenuVB"%> <script runat="server"> ' Use a field to reference the current WebPartManager. Dim _manager As WebPartManager Sub Page_Init(ByVal sender As Object, ByVal e As EventArgs) AddHandler Page.InitComplete, AddressOf InitComplete End Sub Sub InitComplete(ByVal sender As Object, ByVal e As System.EventArgs) _manager = WebPartManager.GetCurrentWebPartManager(Page) Dim browseModeName As String = WebPartManager.BrowseDisplayMode.Name ' Fill the dropdown with the names of supported display modes. Dim mode As WebPartDisplayMode For Each mode In _manager.SupportedDisplayModes Dim modeName As String = mode.Name ' Make sure a mode is enabled before adding it. If mode.IsEnabled(_manager) Then Dim item As New ListItem(modeName, modeName) DisplayModeDropdown.Items.Add(item) End If Next mode ' If shared scope is allowed for this user, display the scope-switching ' UI and select the appropriate radio button for the current user scope. If _manager.Personalization.CanEnterSharedScope Then Panel2.Visible = True If _manager.Personalization.Scope = PersonalizationScope.User Then RadioButton1.Checked = True Else RadioButton2.Checked = True End If End If End Sub ' Change the page to the selected display mode. Sub DisplayModeDropdown_SelectedIndexChanged(ByVal sender As Object, _ ByVal e As EventArgs) Dim selectedMode As String = DisplayModeDropdown.SelectedValue Dim mode As WebPartDisplayMode = _ _manager.SupportedDisplayModes(selectedMode) If Not (mode Is Nothing) Then _manager.DisplayMode = mode End If End Sub ' Set the selected item equal to the current display mode. Sub Page_PreRender(ByVal sender As Object, ByVal e As EventArgs) Dim items As ListItemCollection = DisplayModeDropdown.Items Dim selectedIndex As Integer = _ items.IndexOf(items.FindByText(_manager.DisplayMode.Name)) DisplayModeDropdown.SelectedIndex = selectedIndex End Sub ' Reset all of a user's personalization data for the page. Protected Sub LinkButton1_Click(ByVal sender As Object, _ ByVal e As EventArgs) _manager.Personalization.ResetPersonalizationState() End Sub ' If not in User personalization scope, toggle into it. Protected Sub RadioButton1_CheckedChanged(ByVal sender As Object, _ ByVal e As EventArgs) If _manager.Personalization.Scope = PersonalizationScope.Shared Then _manager.Personalization.ToggleScope() End If End Sub ' If not in Shared scope, and if user is allowed, toggle the scope. Protected Sub RadioButton2_CheckedChanged(ByVal sender As Object, _ ByVal e As EventArgs) If _manager.Personalization.CanEnterSharedScope AndAlso _ _manager.Personalization.Scope = PersonalizationScope.User Then _manager.Personalization.ToggleScope() End If End Sub </script> <div> <asp:Panel ID="Panel1" runat="server" Borderwidth="1" Width="230" BackColor="lightgray" Font-Names="Verdana, Arial, Sans Serif" > <asp:Label ID="Label1" runat="server" Text=" Display Mode" Font-Bold="true" Font-Size="8" Width="120" AssociatedControlID="DisplayModeDropdown"/> <asp:DropDownList ID="DisplayModeDropdown" runat="server" AutoPostBack="true" Width="120" OnSelectedIndexChanged="DisplayModeDropdown_SelectedIndexChanged" /> <asp:LinkButton ID="LinkButton1" runat="server" Text="Reset User State" ToolTip="Reset the current user's personalization data for the page." Font-Size="8" OnClick="LinkButton1_Click" /> <asp:Panel ID="Panel2" runat="server" GroupingText="Personalization Scope" Font-Bold="true" Font-Size="8" Visible="false" > <asp:RadioButton ID="RadioButton1" runat="server" Text="User" AutoPostBack="true" GroupName="Scope" OnCheckedChanged="RadioButton1_CheckedChanged" /> <asp:RadioButton ID="RadioButton2" runat="server" Text="Shared" AutoPostBack="true" GroupName="Scope" OnCheckedChanged="RadioButton2_CheckedChanged" /> </asp:Panel> </asp:Panel> </div>
The second part of the code example is the source code for the two WebPart controls that serve as the consumer and the provider for the connection, and an interface used for the connection points. 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.
Imports System Imports System.Web Imports System.Web.Security Imports System.Security.Permissions Imports System.Web.UI Imports System.Web.UI.WebControls Imports System.Web.UI.WebControls.WebParts Namespace Samples.AspNet.VB.Controls <AspNetHostingPermission(SecurityAction.Demand, _ Level:=AspNetHostingPermissionLevel.Minimal)> _ <AspNetHostingPermission(SecurityAction.InheritanceDemand, _ Level:=AspNetHostingPermissionLevel.Minimal)> _ Public Interface IZipCode Property ZipCode() As String End Interface <AspNetHostingPermission(SecurityAction.Demand, _ Level:=AspNetHostingPermissionLevel.Minimal)> _ <AspNetHostingPermission(SecurityAction.InheritanceDemand, _ Level:=AspNetHostingPermissionLevel.Minimal)> _ Public Class ZipCodeWebPart Inherits WebPart Implements IZipCode Private zipCodeText As String = String.Empty Private input As TextBox Private send As Button Public Sub New() End Sub ' Make the implemented property personalizable to save ' the Zip Code between browser sessions. <Personalizable()> _ Public Property ZipCode() As String _ Implements IZipCode.ZipCode Get Return zipCodeText End Get Set(ByVal value As String) zipCodeText = value End Set End Property ' This is the callback method that returns the provider. <ConnectionProvider("Zip Code Provider", "ZipCodeProvider")> _ Public Function ProvideIZipCode() As IZipCode Return Me End Function Protected Overrides Sub CreateChildControls() Controls.Clear() input = New TextBox() Me.Controls.Add(input) send = New Button() send.Text = "Enter 5-digit Zip Code" AddHandler send.Click, AddressOf Me.submit_Click Me.Controls.Add(send) End Sub Private Sub submit_Click(ByVal sender As Object, _ ByVal e As EventArgs) If input.Text <> String.Empty Then zipCodeText = Page.Server.HtmlEncode(input.Text) input.Text = String.Empty End If End Sub End Class <AspNetHostingPermission(SecurityAction.Demand, _ Level:=AspNetHostingPermissionLevel.Minimal)> _ <AspNetHostingPermission(SecurityAction.InheritanceDemand, _ Level:=AspNetHostingPermissionLevel.Minimal)> _ Public Class WeatherWebPart Inherits WebPart Private _provider As IZipCode Private _zipSearch As String Private DisplayContent As Label ' This method is identified by the ConnectionConsumer ' attribute, and is the mechanism for connecting with ' the provider. <ConnectionConsumer("Zip Code Consumer", "ZipCodeConsumer")> _ Public Sub GetIZipCode(ByVal Provider As IZipCode) _provider = Provider End Sub Protected Overrides Sub OnPreRender(ByVal e As EventArgs) EnsureChildControls() If Not (Me._provider Is Nothing) Then _zipSearch = _provider.ZipCode.Trim() DisplayContent.Text = "My Zip Code is: " + _zipSearch End If End Sub 'OnPreRender Protected Overrides Sub CreateChildControls() Controls.Clear() DisplayContent = New Label() Me.Controls.Add(DisplayContent) End Sub End Class End Namespace
The third part of the code example is the code for the Web page that hosts the controls and demonstrates the use of the Consumer property. Near the top of the page are the Register directives for the user control and the custom controls. Because this example uses dynamic compilation, the Register directive for the source file does not need to reference an assembly name; it includes only an arbitrary tag prefix and the namespace of the controls. In the Button2_Click method, the code accesses the connection object through the WebPartManager control, and gets a reference to the consumer control.
<%@ Page Language="vb" %> <%@ Register TagPrefix="uc1" TagName="DisplayModeMenuVB" Src="~/displaymodemenuvb.ascx" %> <%@ Register TagPrefix="aspSample" 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"> Protected Sub Button1_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) Dim provPoint As ProviderConnectionPoint = _ mgr.GetProviderConnectionPoints(zip1)("ZipCodeProvider") Dim connPoint As ConsumerConnectionPoint = _ mgr.GetConsumerConnectionPoints(weather1)("ZipCodeConsumer") mgr.ConnectWebParts(zip1, provPoint, weather1, connPoint) End Sub Protected Sub Button2_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) Dim consumer as WebPart = mgr.Connections(0).Consumer lbl2.Text = "<h3>Consumer Control Details</h3>" & _ "ID: " & consumer.ID & _ "<br />" & _ "Title: " & consumer.Title End Sub Protected Sub mgr_DisplayModeChanged (ByVal sender as Object, _ ByVal e as WebPartDisplayModeEventArgs) If mgr.DisplayMode Is WebPartManager.ConnectDisplayMode Then Button1.Visible = True Button2.Visible = True Else Button1.Visible = False Button2.Visible = False End If End Sub </script> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>Untitled Page</title> </head> <body> <form id="form1" runat="server"> <div> <asp:WebPartManager ID="mgr" runat="server" OnDisplayModeChanged="mgr_DisplayModeChanged" /> <uc1:DisplayModeMenuVB ID="menu1" runat="server" /> <asp:WebPartZone ID="WebPartZone1" runat="server"> <ZoneTemplate> <aspSample:ZipCodeWebPart ID="zip1" runat="server" Title="Zip Code Provider" /> <aspSample:WeatherWebPart ID="weather1" runat="server" Title="Zip Code Consumer" /> </ZoneTemplate> </asp:WebPartZone> <asp:ConnectionsZone ID="ConnectionsZone1" runat="server"> </asp:ConnectionsZone> <asp:Button ID="Button1" runat="server" Text="Connect WebPart Controls" OnClick="Button1_Click" Visible="false" /> <br /> <asp:Button ID="Button2" runat="server" Text="Display Consumer Info" OnClick="Button2_Click" Visible="false" /> <br /> <asp:Label ID="lbl2" runat="server" /> </div> </form> </body> </html>
After you load the page in a browser, use the Display Mode drop-down list control to switch the page to connect mode. Click the verbs menu (represented by the downward arrow in the title bar) on one of the WebPart controls, and click the connect verb. Use the Connect WebPart Controls button, or the provided connection user interface (UI), to create a connection between the two controls. Click the Display Consumer Info button to run the code that demonstrates the Consumer property.
Available since 2.0