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将值添加到存储在会话中的列表，然后用作中继器的数据源

发布于 2024-12-06 03:16:01 字数 9336 浏览 1 评论 0原文

我的页面上有两个中继器。第一个中继器中有一个 LinkBut​​ton，带有命令名称和命令参数。单击链接按钮时，命令参数的值应该存储在包含列表的会话中。然后我使用会话列表的值来绑定第二个中继器。

我遇到两个问题：

1）我在 OnInit 事件中绑定第二个中继器。在 init 事件之后执行第一个转发器中的 LinkBut​​ton 时执行的事件处理程序 - 因此，当发生数据绑定时，新值尚未添加到会话中。我无法在 init 事件之后绑定数据，因为第二个转发器中的控件需要使用视图状态（或其他）进行维护。

2）在第二个中继器中有两个下拉列表。两者都是中继器 itemdatabound 事件中的数据绑定。当第一个 DDL 更改时，我需要过滤第二个 DDL 中的值。但这并没有发生。

为了提供更清晰的示例，我从应用程序中删除了代码并创建了一个非常简单的 aspx 页面 - 所有代码如下。感谢鲍比已经为此提供了帮助。

真的希望有人能帮助我，因为我很困惑！

标记：

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Repeater-Viewstate.aspx.cs" Inherits="test_Repeater_Viewstate" ViewStateMode="Enabled" %>
<!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></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <h1>Repeater Test</h1>
        <h2>Repeater 1</h2>
        <asp:Repeater runat="server" Visible="true" ID="rptListItems">
            <ItemTemplate>
                Image ID: <asp:Literal ID="ImageID" runat="server" />&nbsp;&nbsp;
                <asp:LinkButton runat="server" CommandName="SelectImage" Text="Add to list" ID="AddToListCommand" />
                <hr />
            </ItemTemplate>
        </asp:Repeater>
        <h2>Repeater 2</h2>
        <asp:Repeater runat="server" Visible="true" ID="rptSelectedItems" ViewStateMode="Enabled">
            <ItemTemplate>
                The value of the item you selected is: <asp:TextBox runat="server" ID="ImageIDInput"/>
                <asp:DropDownList runat="server" ID="OptionsInput" AppendDataBoundItems="true" AutoPostBack="true" >
                    <asp:ListItem Text="Please choose..." Value="0" />
                </asp:DropDownList>
                <asp:DropDownList runat="server" ID="AttributesInput" runat="server" AppendDataBoundItems="true">
                    <asp:ListItem Text="Please choose..." Value="0" />
                </asp:DropDownList>
                <hr style="clear: both;" />
            </ItemTemplate>
        </asp:Repeater>
        <asp:Button runat="server" Text="Postback" />
    </div>
    </form>
</body>
</html>

代码隐藏：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class test_Repeater_Viewstate : System.Web.UI.Page
{

    //DUMMY Data for 1st Repeater
    public class MyRepeaterDataSource {

        public int ID { get; set; }
        public string Title { get; set; }

    }

    private List<MyRepeaterDataSource> _items;
    public List<MyRepeaterDataSource> Items {
        get {
            if (_items == null)
                _items = new List<MyRepeaterDataSource>();
            return _items;
        }
        set {
            _items = value;
        }
    }

    //END dummy data

    //DUMMY data for 1st dropdownlist in second repeater
    public class FirstDDLClass {

        public int ID { get; set; }
        public string Title { get; set; }

    }

    private List<FirstDDLClass> _firstDDLItems;
    public List<FirstDDLClass> FirstDDLItems {
        get {
            if (_firstDDLItems == null)
                _firstDDLItems = new List<FirstDDLClass>();
            return _firstDDLItems;
        }
        set {
            _firstDDLItems = value;
        }
    }

    //DUMMY data for 2nd dropdownlist in second repeater
    public class SecondDDLClass {

        public int ID { get; set; }
        public int ForeignKey { get; set; }
        public string Title { get; set; }
    }

    private List<SecondDDLClass> _secondDDLItems;
    public List<SecondDDLClass> SecondDDLItems {
        get {
            if (_secondDDLItems == null)
                _secondDDLItems = new List<SecondDDLClass>();
            return _secondDDLItems;
        }
        set {
            _secondDDLItems = value;
        }
    }

    public List<string> SelectedItems {
        get {
            if (Session["SelectedItems"] == null)
                Session["SelectedItems"] = new List<string>();
            return (List<string>)(Session["SelectedItems"]);
        }
        set {
            Session["SelectedItems"] = value;
        }
    }


    protected override void OnInit(EventArgs e) {


        //register events
        this.rptListItems.ItemDataBound += new RepeaterItemEventHandler(rptListItems_ItemDataBound);
        this.rptListItems.ItemCommand += new RepeaterCommandEventHandler(rptListItems_ItemCommand);
        this.rptSelectedItems.ItemDataBound += new RepeaterItemEventHandler(rptSelectedItems_ItemDataBound);

        //create a dummy list to populate first repeater
        MyRepeaterDataSource dataSource1 = new MyRepeaterDataSource();
        dataSource1.ID = 1;
        dataSource1.Title = "Item 1";
        Items.Add(dataSource1);

        MyRepeaterDataSource dataSource2 = new MyRepeaterDataSource();
        dataSource2.ID = 2;
        dataSource2.Title = "Item 2";
        Items.Add(dataSource2);

        MyRepeaterDataSource dataSource3 = new MyRepeaterDataSource();
        dataSource3.ID = 3;
        dataSource3.Title = "Item 3";
        Items.Add(dataSource3);

        MyRepeaterDataSource dataSource4 = new MyRepeaterDataSource();
        dataSource4.ID = 4;
        dataSource4.Title = "Item 4";
        Items.Add(dataSource4);

        //create a dummy list to populate the first dropdownlist in the second repeater
        FirstDDLClass class1 = new FirstDDLClass();
        class1.ID = 1;
        class1.Title = "Option 1";
        FirstDDLItems.Add(class1);

        FirstDDLClass class2 = new FirstDDLClass();
        class2.ID = 2;
        class2.Title = "Option 2";
        FirstDDLItems.Add(class2);

        //create a dummy list to populate the second dropdownlist in the second repeater
        SecondDDLClass class3 = new SecondDDLClass();
        class3.ID = 1;
        class3.ForeignKey = 1;
        class3.Title = "Attribute 1";
        SecondDDLItems.Add(class3);

        SecondDDLClass class4 = new SecondDDLClass();
        class4.ID = 1;
        class4.ForeignKey = 1;
        class4.Title = "Attribute 2";
        SecondDDLItems.Add(class4);

        SecondDDLClass class5 = new SecondDDLClass();
        class5.ID = 1;
        class5.ForeignKey = 2;
        class5.Title = "Attribute 3";
        SecondDDLItems.Add(class5);


        if (!this.Page.IsPostBack) {

            //bind 1st repeater
            this.rptListItems.DataSource = Items;
            this.rptListItems.DataBind();

        }

        //bind second repeater
        this.rptSelectedItems.DataSource = SelectedItems;
        this.rptSelectedItems.DataBind();


        base.OnInit(e);
    }

    protected void Page_Load(object sender, EventArgs e)
    {



    }

    void rptListItems_ItemDataBound(object sender, RepeaterItemEventArgs e) {

        Literal imageIDLiteral = e.Item.FindControl("ImageID") as Literal;
        if (imageIDLiteral is Literal) {

            imageIDLiteral.Text = DataBinder.Eval(e.Item.DataItem, "ID").ToString();

        }

        LinkButton linkButton = e.Item.FindControl("AddToListCommand") as LinkButton;
        if (linkButton is LinkButton) {

            linkButton.CommandArgument = DataBinder.Eval(e.Item.DataItem, "ID").ToString();

        }

    }


    void rptListItems_ItemCommand(object source, RepeaterCommandEventArgs e) {

        switch (e.CommandName) {

            case "SelectImage":

                this.SelectedItems.Add(e.CommandArgument.ToString());

                break;

        }

    }

    void rptSelectedItems_ItemDataBound(object sender, RepeaterItemEventArgs e) {

        switch (e.Item.ItemType) {

            case ListItemType.AlternatingItem:
            case ListItemType.Item:

                TextBox textBox = e.Item.FindControl("ImageIDInput") as TextBox;
                if (textBox is TextBox) {

                    textBox.Text = e.Item.DataItem.ToString();

                }

                DropDownList ddl1 = e.Item.FindControl("OptionsInput") as DropDownList;
                if (ddl1 is DropDownList) {

                    ddl1.DataValueField = "ID";
                    ddl1.DataTextField = "Title";
                    ddl1.DataSource = this.FirstDDLItems;
                    ddl1.DataBind();

                }

                DropDownList ddl2 = e.Item.FindControl("AttributesInput") as DropDownList;
                if (ddl2 is DropDownList) {

                    ddl2.DataValueField = "ID";
                    ddl2.DataTextField = "Title";
                    if (ddl1.SelectedIndex != 0) {
                        ddl2.DataSource = this.SecondDDLItems.Where(f => f.ForeignKey == Convert.ToInt32(ddl1.SelectedValue));
                        ddl2.DataBind();
                    }

                }




                break;

        }

    }

}

提前感谢各位

Al

原文

I have two repeaters on my page. The first repeater has a LinkButton in it, with a commandname and commandarguement. When the linkbutton is clicked the value of commandarguement is supposed to be stored in a Session containing List. Then I use the value of Session List to bind the second repeater.

I am having two problems:

1) I am binding the second repeater in the OnInit event. The event handler that is executed when the LinkButton in the first repeater is executed AFTER the init event - therefore when data binding takes place the new value has not been added to the session yet. I can't bind the data any later than the init event because the controls within the second repeater need to be maintained using viewstate (or other).

2) In the second repeater there are two dropdownlists. Both are databound in the repeaters itemdatabound event. When the first DDL is changed, I need to filter the values in the second DDL. But this just isnt happening.

For the purposes of a clearer example, I have stripped the code out of my application and created a very simple aspx page - all of the code is below. Thanks to Bobby who has already helped with this.

Really hope someone can help as I am stumped!

Markup:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Repeater-Viewstate.aspx.cs" Inherits="test_Repeater_Viewstate" ViewStateMode="Enabled" %>
<!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></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <h1>Repeater Test</h1>
        <h2>Repeater 1</h2>
        <asp:Repeater runat="server" Visible="true" ID="rptListItems">
            <ItemTemplate>
                Image ID: <asp:Literal ID="ImageID" runat="server" />  
                <asp:LinkButton runat="server" CommandName="SelectImage" Text="Add to list" ID="AddToListCommand" />
                <hr />
            </ItemTemplate>
        </asp:Repeater>
        <h2>Repeater 2</h2>
        <asp:Repeater runat="server" Visible="true" ID="rptSelectedItems" ViewStateMode="Enabled">
            <ItemTemplate>
                The value of the item you selected is: <asp:TextBox runat="server" ID="ImageIDInput"/>
                <asp:DropDownList runat="server" ID="OptionsInput" AppendDataBoundItems="true" AutoPostBack="true" >
                    <asp:ListItem Text="Please choose..." Value="0" />
                </asp:DropDownList>
                <asp:DropDownList runat="server" ID="AttributesInput" runat="server" AppendDataBoundItems="true">
                    <asp:ListItem Text="Please choose..." Value="0" />
                </asp:DropDownList>
                <hr style="clear: both;" />
            </ItemTemplate>
        </asp:Repeater>
        <asp:Button runat="server" Text="Postback" />
    </div>
    </form>
</body>
</html>

Code behind:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class test_Repeater_Viewstate : System.Web.UI.Page
{

    //DUMMY Data for 1st Repeater
    public class MyRepeaterDataSource {

        public int ID { get; set; }
        public string Title { get; set; }

    }

    private List<MyRepeaterDataSource> _items;
    public List<MyRepeaterDataSource> Items {
        get {
            if (_items == null)
                _items = new List<MyRepeaterDataSource>();
            return _items;
        }
        set {
            _items = value;
        }
    }

    //END dummy data

    //DUMMY data for 1st dropdownlist in second repeater
    public class FirstDDLClass {

        public int ID { get; set; }
        public string Title { get; set; }

    }

    private List<FirstDDLClass> _firstDDLItems;
    public List<FirstDDLClass> FirstDDLItems {
        get {
            if (_firstDDLItems == null)
                _firstDDLItems = new List<FirstDDLClass>();
            return _firstDDLItems;
        }
        set {
            _firstDDLItems = value;
        }
    }

    //DUMMY data for 2nd dropdownlist in second repeater
    public class SecondDDLClass {

        public int ID { get; set; }
        public int ForeignKey { get; set; }
        public string Title { get; set; }
    }

    private List<SecondDDLClass> _secondDDLItems;
    public List<SecondDDLClass> SecondDDLItems {
        get {
            if (_secondDDLItems == null)
                _secondDDLItems = new List<SecondDDLClass>();
            return _secondDDLItems;
        }
        set {
            _secondDDLItems = value;
        }
    }

    public List<string> SelectedItems {
        get {
            if (Session["SelectedItems"] == null)
                Session["SelectedItems"] = new List<string>();
            return (List<string>)(Session["SelectedItems"]);
        }
        set {
            Session["SelectedItems"] = value;
        }
    }


    protected override void OnInit(EventArgs e) {


        //register events
        this.rptListItems.ItemDataBound += new RepeaterItemEventHandler(rptListItems_ItemDataBound);
        this.rptListItems.ItemCommand += new RepeaterCommandEventHandler(rptListItems_ItemCommand);
        this.rptSelectedItems.ItemDataBound += new RepeaterItemEventHandler(rptSelectedItems_ItemDataBound);

        //create a dummy list to populate first repeater
        MyRepeaterDataSource dataSource1 = new MyRepeaterDataSource();
        dataSource1.ID = 1;
        dataSource1.Title = "Item 1";
        Items.Add(dataSource1);

        MyRepeaterDataSource dataSource2 = new MyRepeaterDataSource();
        dataSource2.ID = 2;
        dataSource2.Title = "Item 2";
        Items.Add(dataSource2);

        MyRepeaterDataSource dataSource3 = new MyRepeaterDataSource();
        dataSource3.ID = 3;
        dataSource3.Title = "Item 3";
        Items.Add(dataSource3);

        MyRepeaterDataSource dataSource4 = new MyRepeaterDataSource();
        dataSource4.ID = 4;
        dataSource4.Title = "Item 4";
        Items.Add(dataSource4);

        //create a dummy list to populate the first dropdownlist in the second repeater
        FirstDDLClass class1 = new FirstDDLClass();
        class1.ID = 1;
        class1.Title = "Option 1";
        FirstDDLItems.Add(class1);

        FirstDDLClass class2 = new FirstDDLClass();
        class2.ID = 2;
        class2.Title = "Option 2";
        FirstDDLItems.Add(class2);

        //create a dummy list to populate the second dropdownlist in the second repeater
        SecondDDLClass class3 = new SecondDDLClass();
        class3.ID = 1;
        class3.ForeignKey = 1;
        class3.Title = "Attribute 1";
        SecondDDLItems.Add(class3);

        SecondDDLClass class4 = new SecondDDLClass();
        class4.ID = 1;
        class4.ForeignKey = 1;
        class4.Title = "Attribute 2";
        SecondDDLItems.Add(class4);

        SecondDDLClass class5 = new SecondDDLClass();
        class5.ID = 1;
        class5.ForeignKey = 2;
        class5.Title = "Attribute 3";
        SecondDDLItems.Add(class5);


        if (!this.Page.IsPostBack) {

            //bind 1st repeater
            this.rptListItems.DataSource = Items;
            this.rptListItems.DataBind();

        }

        //bind second repeater
        this.rptSelectedItems.DataSource = SelectedItems;
        this.rptSelectedItems.DataBind();


        base.OnInit(e);
    }

    protected void Page_Load(object sender, EventArgs e)
    {



    }

    void rptListItems_ItemDataBound(object sender, RepeaterItemEventArgs e) {

        Literal imageIDLiteral = e.Item.FindControl("ImageID") as Literal;
        if (imageIDLiteral is Literal) {

            imageIDLiteral.Text = DataBinder.Eval(e.Item.DataItem, "ID").ToString();

        }

        LinkButton linkButton = e.Item.FindControl("AddToListCommand") as LinkButton;
        if (linkButton is LinkButton) {

            linkButton.CommandArgument = DataBinder.Eval(e.Item.DataItem, "ID").ToString();

        }

    }


    void rptListItems_ItemCommand(object source, RepeaterCommandEventArgs e) {

        switch (e.CommandName) {

            case "SelectImage":

                this.SelectedItems.Add(e.CommandArgument.ToString());

                break;

        }

    }

    void rptSelectedItems_ItemDataBound(object sender, RepeaterItemEventArgs e) {

        switch (e.Item.ItemType) {

            case ListItemType.AlternatingItem:
            case ListItemType.Item:

                TextBox textBox = e.Item.FindControl("ImageIDInput") as TextBox;
                if (textBox is TextBox) {

                    textBox.Text = e.Item.DataItem.ToString();

                }

                DropDownList ddl1 = e.Item.FindControl("OptionsInput") as DropDownList;
                if (ddl1 is DropDownList) {

                    ddl1.DataValueField = "ID";
                    ddl1.DataTextField = "Title";
                    ddl1.DataSource = this.FirstDDLItems;
                    ddl1.DataBind();

                }

                DropDownList ddl2 = e.Item.FindControl("AttributesInput") as DropDownList;
                if (ddl2 is DropDownList) {

                    ddl2.DataValueField = "ID";
                    ddl2.DataTextField = "Title";
                    if (ddl1.SelectedIndex != 0) {
                        ddl2.DataSource = this.SecondDDLItems.Where(f => f.ForeignKey == Convert.ToInt32(ddl1.SelectedValue));
                        ddl2.DataBind();
                    }

                }




                break;

        }

    }

}

Thanks in advance guys

Al

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评论（1）

二智少女 2024-12-13 03:16:01

如果添加以下代码：

    protected void OptionsInput_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList optionsInput = sender as DropDownList;
        DropDownList ddl2 = optionsInput.Parent.FindControl("AttributesInput") as DropDownList;
        if (ddl2 is DropDownList)
        {

            ddl2.DataValueField = "ID";
            ddl2.DataTextField = "Title";
            if (optionsInput.SelectedIndex != 0)
            {
                ddl2.DataSource = this.SecondDDLItems.Where(f => f.ForeignKey == Convert.ToInt32(optionsInput.SelectedValue));
                ddl2.DataBind();
            }

        }
    }

和以下标记：

<asp:DropDownList runat="server" ID="OptionsInput" AppendDataBoundItems="true" AutoPostBack="true" OnSelectedIndexChanged="OptionsInput_SelectedIndexChanged" >

（具体来说，添加 OnSelectedIndexChanged="OptionsInput_SelectedIndexChanged"）

它对我有用。

If you add the following code:

    protected void OptionsInput_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList optionsInput = sender as DropDownList;
        DropDownList ddl2 = optionsInput.Parent.FindControl("AttributesInput") as DropDownList;
        if (ddl2 is DropDownList)
        {

            ddl2.DataValueField = "ID";
            ddl2.DataTextField = "Title";
            if (optionsInput.SelectedIndex != 0)
            {
                ddl2.DataSource = this.SecondDDLItems.Where(f => f.ForeignKey == Convert.ToInt32(optionsInput.SelectedValue));
                ddl2.DataBind();
            }

        }
    }

And the following markup:

<asp:DropDownList runat="server" ID="OptionsInput" AppendDataBoundItems="true" AutoPostBack="true" OnSelectedIndexChanged="OptionsInput_SelectedIndexChanged" >

(Specifically, adding the OnSelectedIndexChanged="OptionsInput_SelectedIndexChanged")

It worked for me.

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