Question

我有两个DropDownLists，一个用于士兵类型，另一个用于玩家允许购买的士兵数量。我在aspx页面中使用LinqDataSource填充ddlSoldiers，如下所示：

<asp:DropDownList ID="ddlSoldiers" runat="server" 
                    DataSourceID="LinqDataSource2" DataTextField="type" 
                    DataValueField="troopid" AutoPostBack="True">
                </asp:DropDownList>
                <asp:LinqDataSource ID="LinqDataSource2" runat="server" 
                    ContextTypeName="BrowserSpill.LinqClass1DataContext" EntityTypeName="" 
                    Select="new (type, troopid)" TableName="Troops">
                </asp:LinqDataSource>

另一个列表ddlSoldierNumber在页面加载中填充，如下所示：

protected void Page_Load(object sender, EventArgs e)
    {

        if (Session["userRole"] == null || Session["userRole"].Equals("admin"))
        {
            Response.Redirect("Login.aspx");
        }

        int userid = Convert.ToInt32(Session["userid"]);

        if(string.IsNullOrEmpty(ddlSoldiers.SelectedValue))
        {
            var varTroopType = dc.Troops.Single(t => t.troopid == 1).type;
            string troopType = Convert.ToString(varTroopType);

            var varBuildingId = dc.Buildings.Single(b => b.soldierType == troopType).buildingid;
            int buildingId = Convert.ToInt32(varBuildingId);

            var varNumberOfBuildings =
            dc.Towns.Single(t => (t.buildingid == buildingId) && (t.userid == userid)).number;

            int numberOfBuildings = Convert.ToInt32(varNumberOfBuildings);

            for (int i = 1; i < numberOfBuildings + 1; i++)
            {
                ddlSoldierNumber.Items.Add(i.ToString());
            }
        }
        else
        {

            ddlSoldierNumber.Items.Clear();

            string troopType = ddlSoldiers.SelectedItem.Text;

            var varBuildingId = dc.Buildings.Single(b => b.soldierType == troopType).buildingid;
            int buildingId = Convert.ToInt32(varBuildingId);

            var varNumberOfBuildings =
                dc.Towns.Single(t => (t.buildingid == buildingId) && (t.userid == userid)).number;

            int numberOfBuildings = Convert.ToInt32(varNumberOfBuildings);


            for(int i = 1; i < numberOfBuildings+1; i++)
            {
                ddlSoldierNumber.Items.Add(i.ToString());
            }

        }
    }

但是当我想从ddlSoldierNumber获取值时，我只获得该列表中的第一个值。我尝试通过点击这样的按钮来获取数字：

protected void btnBuySoldier_Click(object sender, EventArgs e)
    {
        string numbertobuy = ddlSoldierNumber.SelectedItem.Value;
        lblAntall.Text = numbertobuy;
    }

我试过这句话：

ddlSoldierNumber.Items.Clear();

其他地方，但没有任何运气。在按下按钮之后和ddlSoldierNumber重新填充之前，有谁知道如何清除数字列表？

Answer 1

如果要根据ddlSoldiers中的选择填充ddlSoldierNumber，则无法在页面加载事件中向ddlSoldierNumber添加值。为此，您必须在（ddlSoldiers）选定的索引更改事件中添加页面加载事件代码。

protected void ddlSoldiers_SelectedIndexChanged(object sender, EventArgs e)
{
    if (Session["userRole"] == null || Session["userRole"].Equals("admin"))
    {
        Response.Redirect("Login.aspx");
    }

    int userid = Convert.ToInt32(Session["userid"]);

    if (string.IsNullOrEmpty(ddlSoldiers.SelectedValue))
    {
        var varTroopType = dc.Troops.Single(t => t.troopid == 1).type;
        string troopType = Convert.ToString(varTroopType);

        var varBuildingId = dc.Buildings.Single(b => b.soldierType == troopType).buildingid;
        int buildingId = Convert.ToInt32(varBuildingId);

        var varNumberOfBuildings =
        dc.Towns.Single(t => (t.buildingid == buildingId) && (t.userid == userid)).number;

        int numberOfBuildings = Convert.ToInt32(varNumberOfBuildings);

        for (int i = 1; i < numberOfBuildings + 1; i++)
        {
            ddlSoldierNumber.Items.Add(i.ToString());
        }
    }
    else
    {

        ddlSoldierNumber.Items.Clear();

        string troopType = ddlSoldiers.SelectedItem.Text;

        var varBuildingId = dc.Buildings.Single(b => b.soldierType == troopType).buildingid;
        int buildingId = Convert.ToInt32(varBuildingId);

        var varNumberOfBuildings =
            dc.Towns.Single(t => (t.buildingid == buildingId) && (t.userid == userid)).number;

        int numberOfBuildings = Convert.ToInt32(varNumberOfBuildings);


        for (int i = 1; i < numberOfBuildings + 1; i++)
        {
            ddlSoldierNumber.Items.Add(i.ToString());
        }

    }

}

Answer 2

如果我没记错的话，页面加载在按钮的事件处理程序之前运行，你是否尝试过放置ddlSolderNumber.Items.Clear（）;更改标签后在Click事件处理程序中？（我知道这不能解决你的第一个问题）

为此你可以尝试:(如果我很困惑，我道歉，我不好解释自己）您可以为ddlSoldierNumber列表创建一个“填充”方法，在单击事件后调用该方法。在你的页面加载中，你可以检查“if（！PostBack）”运行你的默认启动逻辑。

从DropDownList中删除项目

2 个答案: