從DropDownList中移除物品

Question

我有兩個DropDownLists一個用於士兵的類型，一個用於我允許購買的玩家的士兵數量。我填充ddlSoldiers，像這樣在ASPX頁面的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> 

另一個列表ddlSoldierNumber在頁面加載填充像這樣：

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，當我想從ddlSoldierNumber我的價值觀只獲得該列表中的第一個值。我嘗試用一​​個按鈕的點擊這樣得到的數字：

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

我曾試圖放線：

ddlSoldierNumber.Items.Clear(); 

其他地方，但沒有任何的運氣。有沒有人知道我按下按鈕之後，ddlSoldierNumber重新填充之前如何清除號碼列表？

Answer 1

如果您想根據ddlSoldiers中的選擇填充ddlSoldierNumber，那麼您無法在頁面加載事件中將值添加到ddlSoldierNumber中。爲此，您必須在（ddlSoldiers）選定的索引更改事件中添加頁面加載事件代碼。

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

如果我沒有記錯，頁面加載是在按鈕的事件處理程序之前運行的，您是否嘗試過放置ddlSolderNumber.Items.Clear（）;在更改標籤後，Click事件處理程序中？ （我知道這並不解決您的第一個問題的問題）

對於您可以嘗試：（如果林困惑我道歉，林壞在解釋自己） 你可以爲你的ddlSoldierNumber列表創建一個「填充」方法，您在點擊事件後致電。 在你的頁面載入中，你可以檢查「if（！PostBack）」運行你的默認啓動邏輯。