从DropDownList中移除物品

Question

我有两个DropDownLists一个用于士兵的类型，一个用于我允许购买的玩家的士兵数量。我填充ddlSoldiers，像这样在ASPX页面的LinqDataSource：

<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在页面加载填充像这样：

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我的价值观只获得该列表中的第一个值。我尝试用一​​个按钮的点击这样得到的数字：

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

我曾试图放线：

ddlSoldierNumber.Items.Clear(); 

其他地方，但没有任何的运气。有没有人知道我按下按钮之后，ddlSoldierNumber重新填充之前如何清除号码列表？

Answer 1

如果您想根据ddlSoldiers中的选择填充ddlSoldierNumber，那么您无法在页面加载事件中将值添加到ddlSoldierNumber中。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

如果我没有记错，页面加载是在按钮的事件处理程序之前运行的，您是否尝试过放置ddlSolderNumber.Items.Clear（）;在更改标签后，Click事件处理程序中？ （我知道这并不解决您的第一个问题的问题）

对于您可以尝试：（如果林困惑我道歉，林坏在解释自己） 你可以为你的ddlSoldierNumber列表创建一个“填充”方法，您在点击事件后致电。 在你的页面载入中，你可以检查“if（！PostBack）”运行你的默认启动逻辑。