Question

我需要相互加载下拉列表。我做了如下：

<asp:DropDownList ID="drblLanguages" runat="server" OnSelectedIndexChanged="drblLanguages_SelectedIndexChanged" AutoPostBack="true">
        </asp:DropDownList>

  <asp:DropDownList ID="DrpCategory" runat="server" OnSelectedIndexChanged="DrpCategory_SelectedIndexChanged" AutoPostBack="true" EnableViewState="true">
        </asp:DropDownList>

 <asp:DropDownList ID="DrpEmailTemplate" runat="server" Enabled="false" OnSelectedIndexChanged="DrpEmailTemplate_SelectedIndexChanged" AutoPostBack="true">
        </asp:DropDownList>

我的后端代码如下：

  protected void drblLanguages_SelectedIndexChanged(object sender, EventArgs e)
        {
            try
            {
                LoadDataForCategoty();               
            }
            catch (Exception ex)
            {
                SendToErrorPage(ex);
            }
        }

   protected void DrpCategory_SelectedIndexChanged(object sender, EventArgs e)
        {
            try
            {
                    LoadEmailTemplateToDropDown();

            }
            catch (Exception ex)
            {
                SendToErrorPage(ex);
            }
        }

在Page_load事件中

   protected override void OnInit(EventArgs e)
     {
        try
        {              
            LoadLanguageDropdowns();
        }
        catch (Exception ex)
        {
            SendToErrorPage(ex);
        }
     }

在此处语言更改时会加载相关类别。但是当类别被更改时，它总是选择第一个记录（索引-1）并且它调用drblLanguages_SelectedIndexChanged事件而不是DrpCategory_SelectedIndexChanged。似乎下拉从头再次初始化。我该如何解决这个问题？

Answer 1

if(!IsPostBack)
{
    LoadLanguageDropdowns();
}

你试试这个吗？您应该在Page_Load中加载下拉列表，而不是在OnInit中。这将仅在首次打开时加载您的下拉列表，并且不应出现您的问题。

编辑：您有三个下拉列表

        <asp:DropDownList runat="server" ID="LanguageDdl"  OnSelectedIndexChanged="LanguageDdl_SelectedIndexChanged" DataTextField="Title" DataValueField="ID" AutoPostBack="true">
        </asp:DropDownList>
        <asp:DropDownList runat="server" ID="CategoryDdl" OnSelectedIndexChanged="CategoryDdl_SelectedIndexChanged" DataTextField="Title" DataValueField="ID" AutoPostBack="true">
        </asp:DropDownList>
        <asp:DropDownList runat="server" ID="TemplateDdl" OnSelectedIndexChanged="TemplateDdl_SelectedIndexChanged" DataTextField="Title" DataValueField="ID" AutoPostBack="true">
        </asp:DropDownList>

代码背后：

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            LanguageDdl.DataSource = new Varmebaronen.AppCode.BO.Object().GetList();
            LanguageDdl.DataBind();
        }

    }

    protected void LanguageDdl_SelectedIndexChanged(object sender, EventArgs e)
    {
        //if query the database for dataSource like in my case here you can
        // take value of the languagedropdown and fetch the category for the current language
        CategoryDdl.DataSource = new Varmebaronen.AppCode.BO.Category().GetList();
        CategoryDdl.DataBind();
    }
    protected void CategoryDdl_SelectedIndexChanged(object sender, EventArgs e)
    {
        TemplateDdl.DataSource = new Varmebaronen.AppCode.BO.Product().GetList();
        TemplateDdl.DataBind();
    }

    protected void TemplateDdl_SelectedIndexChanged(object sender, EventArgs e)
    {

    }

在asp.net中基于彼此加载3下拉

1 个答案: