WebPartConnection.Consumer 属性
定义
public:
property System::Web::UI::WebControls::WebParts::WebPart ^ Consumer { System::Web::UI::WebControls::WebParts::WebPart ^ get(); };
[System.ComponentModel.Browsable(false)]
public System.Web.UI.WebControls.WebParts.WebPart Consumer { get; }
[<System.ComponentModel.Browsable(false)>]
member this.Consumer : System.Web.UI.WebControls.WebParts.WebPart
Public ReadOnly Property Consumer As WebPart
属性值
一个 WebPart,表示作为连接中的使用者的 Web 部件控件。A WebPart that represents the Web Parts control acting as the consumer in a connection.
- 属性
例外
ConsumerID 属性的长度为零。The length of the ConsumerID property is zero.
示例
下面的代码示例演示如何以编程方式使用 Consumer 属性。The following code example demonstrates the programmatic use of the Consumer property.
此代码示例包含四个部分:The code example has four parts:
允许您在页上更改 Web 部件显示模式的用户控件。A user control that enables you to change the Web Parts display mode on a page.
接口的源代码和两个用作 WebPart 连接的提供者和使用者的控件。Source code for an interface and two WebPart controls acting as the provider and the consumer for a connection.
承载所有控件并运行代码示例的网页。A Web page to host all the controls and run the code example.
有关如何运行 "示例" 页的说明。An explanation of how to run the example page.
此代码示例的第一部分是用户控件,该控件使用户能够更改网页上的显示模式。The first part of this code example is the user control that enables users to change display modes on a Web page. 将以下源代码保存到 .ascx 文件,并为其提供分配给 Src 此用户控件的指令属性的文件名,该属性 Register 位于宿主网页的顶部附近。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. 有关显示模式的详细信息以及此控件中源代码的说明,请参阅 演练:在 Web 部件页上更改显示模式。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="C#" classname="DisplayModeMenuCS"%>
<script runat="server">
// Use a field to reference the current WebPartManager.
WebPartManager _manager;
void Page_Init(object sender, EventArgs e)
{
Page.InitComplete += new EventHandler(InitComplete);
}
void InitComplete(object sender, System.EventArgs e)
{
_manager = WebPartManager.GetCurrentWebPartManager(Page);
String browseModeName = WebPartManager.BrowseDisplayMode.Name;
// Fill the dropdown with the names of supported display modes.
foreach (WebPartDisplayMode mode in _manager.SupportedDisplayModes)
{
String modeName = mode.Name;
// Make sure a mode is enabled before adding it.
if (mode.IsEnabled(_manager))
{
ListItem item = new ListItem(modeName, modeName);
DisplayModeDropdown.Items.Add(item);
}
}
// 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)
{
Panel2.Visible = true;
if (_manager.Personalization.Scope == PersonalizationScope.User)
RadioButton1.Checked = true;
else
RadioButton2.Checked = true;
}
}
// Change the page to the selected display mode.
void DisplayModeDropdown_SelectedIndexChanged(object sender, EventArgs e)
{
String selectedMode = DisplayModeDropdown.SelectedValue;
WebPartDisplayMode mode = _manager.SupportedDisplayModes[selectedMode];
if (mode != null)
_manager.DisplayMode = mode;
}
// Set the selected item equal to the current display mode.
void Page_PreRender(object sender, EventArgs e)
{
ListItemCollection items = DisplayModeDropdown.Items;
int selectedIndex =
items.IndexOf(items.FindByText(_manager.DisplayMode.Name));
DisplayModeDropdown.SelectedIndex = selectedIndex;
}
// Reset all of a user's personalization data for the page.
protected void LinkButton1_Click(object sender, EventArgs e)
{
_manager.Personalization.ResetPersonalizationState();
}
// If not in User personalization scope, toggle into it.
protected void RadioButton1_CheckedChanged(object sender, EventArgs e)
{
if (_manager.Personalization.Scope == PersonalizationScope.Shared)
_manager.Personalization.ToggleScope();
}
// If not in Shared scope, and if user is allowed, toggle the scope.
protected void RadioButton2_CheckedChanged(object sender, EventArgs e)
{
if (_manager.Personalization.CanEnterSharedScope &&
_manager.Personalization.Scope == PersonalizationScope.User)
_manager.Personalization.ToggleScope();
}
</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>
<%@ 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>
此代码示例的第二部分是 WebPart 作为使用者和连接的提供程序的两个控件的源代码,以及用于连接点的接口。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. 要使代码示例运行,必须编译此源代码。For the code example to run, you must compile this source code. 可以显式编译该程序集,并将生成的程序集放在网站的 Bin 文件夹或全局程序集缓存中。You can compile it explicitly and put the resulting assembly in your Web site's Bin folder or the global assembly cache. 或者,您可以将源代码放在站点的 App_Code 文件夹中,它将在运行时动态编译。Alternatively, you can put the source code in your site's App_Code folder, where it will be dynamically compiled at run time. 此代码示例使用动态编译。This code example uses dynamic compilation. 有关演示如何编译的演练,请参阅 演练:开发和使用自定义 Web 服务器控件。For a walkthrough that demonstrates how to compile, see Walkthrough: Developing and Using a Custom Web Server Control.
namespace Samples.AspNet.CS.Controls
{
using System;
using System.Web;
using System.Web.Security;
using System.Security.Permissions;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
[AspNetHostingPermission(SecurityAction.Demand,
Level = AspNetHostingPermissionLevel.Minimal)]
[AspNetHostingPermission(SecurityAction.InheritanceDemand,
Level = AspNetHostingPermissionLevel.Minimal)]
public interface IZipCode
{
string ZipCode { get; set;}
}
[AspNetHostingPermission(SecurityAction.Demand,
Level = AspNetHostingPermissionLevel.Minimal)]
[AspNetHostingPermission(SecurityAction.InheritanceDemand,
Level = AspNetHostingPermissionLevel.Minimal)]
public class ZipCodeWebPart : WebPart, IZipCode
{
string zipCodeText = String.Empty;
TextBox input;
Button send;
public ZipCodeWebPart()
{
}
// Make the implemented property personalizable to save
// the Zip Code between browser sessions.
[Personalizable()]
public virtual string ZipCode
{
get { return zipCodeText; }
set { zipCodeText = value; }
}
// This is the callback method that returns the provider.
[ConnectionProvider("Zip Code Provider", "ZipCodeProvider")]
public IZipCode ProvideIZipCode()
{
return this;
}
protected override void CreateChildControls()
{
Controls.Clear();
input = new TextBox();
this.Controls.Add(input);
send = new Button();
send.Text = "Enter 5-digit Zip Code";
send.Click += new EventHandler(this.submit_Click);
this.Controls.Add(send);
}
private void submit_Click(object sender, EventArgs e)
{
if (!string.IsNullOrEmpty(input.Text))
{
zipCodeText = Page.Server.HtmlEncode(input.Text);
input.Text = String.Empty;
}
}
}
[AspNetHostingPermission(SecurityAction.Demand,
Level = AspNetHostingPermissionLevel.Minimal)]
[AspNetHostingPermission(SecurityAction.InheritanceDemand,
Level = AspNetHostingPermissionLevel.Minimal)]
public class WeatherWebPart : WebPart
{
private IZipCode _provider;
string _zipSearch;
Label DisplayContent;
// This method is identified by the ConnectionConsumer
// attribute, and is the mechanism for connecting with
// the provider.
[ConnectionConsumer("Zip Code Consumer", "ZipCodeConsumer")]
public void GetIZipCode(IZipCode Provider)
{
_provider = Provider;
}
protected override void OnPreRender(EventArgs e)
{
EnsureChildControls();
if (this._provider != null)
{
_zipSearch = _provider.ZipCode.Trim();
DisplayContent.Text = "My Zip Code is: " + _zipSearch;
}
}
protected override void CreateChildControls()
{
Controls.Clear();
DisplayContent = new Label();
this.Controls.Add(DisplayContent);
}
}
}
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
Protected Overrides Sub CreateChildControls()
Controls.Clear()
DisplayContent = New Label()
Me.Controls.Add(DisplayContent)
End Sub
End Class
End Namespace
此代码示例的第三部分是承载控件的网页的代码,并演示属性的用法 Consumer 。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. 页面顶部附近是 Register 用户控件和自定义控件的指令。Near the top of the page are the Register directives for the user control and the custom controls. 由于本示例使用动态编译,因此 Register 源文件的指令不需要引用程序集名称; 它只包含控件的任意标记前缀和命名空间。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. 在 Button2_Click 方法中,代码通过控件访问连接对象 WebPartManager ,并获取对使用者控件的引用。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="C#" %>
<%@ Register TagPrefix="uc1"
TagName="DisplayModeMenuCS"
Src="~/displaymodemenucs.ascx" %>
<%@ Register TagPrefix="aspSample"
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">
protected void Button1_Click(object sender, EventArgs e)
{
ProviderConnectionPoint provPoint =
mgr.GetProviderConnectionPoints(zip1)["ZipCodeProvider"];
ConsumerConnectionPoint connPoint =
mgr.GetConsumerConnectionPoints(weather1)["ZipCodeConsumer"];
WebPartConnection conn1 = mgr.ConnectWebParts(zip1, provPoint,
weather1, connPoint);
}
protected void Button2_Click(object sender, EventArgs e)
{
WebPart consumer = mgr.Connections[0].Consumer;
lbl2.Text = "<h3>Consumer Control Details</h3>" +
"ID: " + consumer.ID +
"<br />" +
"Title: " + consumer.Title;
}
protected void mgr_DisplayModeChanged(object sender,
WebPartDisplayModeEventArgs e)
{
if (mgr.DisplayMode == WebPartManager.ConnectDisplayMode)
{
Button1.Visible = true;
Button2.Visible = true;
}
else
{
Button1.Visible = false;
Button2.Visible = false;
}
}
</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:DisplayModeMenuCS 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>
<%@ 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>
在浏览器中加载页面后,请使用 " 显示模式 " 下拉列表控件将页面切换到连接模式。After you load the page in a browser, use the Display Mode drop-down list control to switch the page to connect mode. 单击谓词菜单 (由标题栏中的向下箭头表示) 一个 WebPart 控件上,然后单击 "连接" 谓词。Click the verbs menu (represented by the downward arrow in the title bar) on one of the WebPart controls, and click the connect verb. 使用 " 连接" WebPart 控件 按钮或提供的连接用户界面 (UI) ,以创建两个控件之间的连接。Use the Connect WebPart Controls button, or the provided connection user interface (UI), to create a connection between the two controls. 单击 " 显示使用者信息 " 按钮,以运行演示属性的代码 Consumer 。Click the Display Consumer Info button to run the code that demonstrates the Consumer property.
注解
每个 Web 部件连接包含共享数据的两个控件。Every Web Parts connection consists of two controls that share data. 一个控件充当数据的提供程序,另一个控件作为使用者,接收和处理来自提供程序的数据。One control acts as the provider of data, and the other control acts as a consumer, receiving and processing the data from the provider. Consumer属性获取对 WebPart 在连接关系中充当使用者的控件的引用。The Consumer property gets a reference to the WebPart control acting as a consumer in a connection relationship.