ASP.Net 下拉列表不会重新显示我选择的选项

Question

我有一个 4 页的 ASP.NET 表单，它在会话中存储数据。所有这些工作正常，但我在检索用户最初从我的下拉列表中选择的值时遇到问题。

第 1 页HTML 带 DropDownList

<asp:DropDownList ID="ddlInnoc" runat="server" class="form-control">
     <asp:ListItem Value="0">- - Please Select - -</asp:ListItem>
     <asp:ListItem Value="Male">Male</asp:ListItem>
     <asp:ListItem Value="Female">Female</asp:ListItem>
</asp:DropDownList>

第 1 页代码后面重新显示所选值

protected void Page_Load(object sender, EventArgs e)
    {
        if (txtData1.Text == string.Empty && Session["pg1input"] != null)
        {
            txtData1.Text = Session["pg1input"].ToString();
        }

        if (ddlInnoc.SelectedValue == string.Empty && Session["pg1dd"] != null)
        {
            ddlInnoc.SelectedValue = Session["pg1dd"].ToString();
        }
    }

    protected void pg1button_Click(object sender, EventArgs e)
    {
        Session["pg1input"] = txtData1.Text;
        Session["pg1dd"] = ddlInnoc.SelectedValue;
        Response.Redirect("/Session/pg2.aspx");
    }

第3页HTML代码

            <div class="form-group">
                <div class="col-xs-12">
                    <asp:Label ID="Label1" class="col-md-2 control-label" runat="server" Text="Name:"></asp:Label>
                    <div class="col-md-3 form-control-static">
                        <%=Session["pg1input"] %>
                    </div>
                </div>
            </div>
            <div class="form-group">
                <div class="col-xs-12">
                    <asp:Label ID="Label2" class="col-md-2 control-label" runat="server" Text="Sex:"></asp:Label>
                    <div class="col-md-3 form-control-static">
                        <%=Session["pg1dd"] %>
                    </div>
                </div>
            </div>
<div class="row">
     <div class="col-sm-offset-4 col-xs-12">
          <asp:LinkButton ID="pg1EditButton" runat="server" OnClick="pg1EditButton_Click" CssClass="btn btn-default">
               <span aria-hidden="true" class="glyphicon glyphicon-pencil"></span> Edit
          </asp:LinkButton>
     </div>
</div>

第3页编辑后面的按钮代码

protected void pg1EditButton_Click(object sender, EventArgs e)
{
    Response.Redirect("/Session/pg1.aspx");
}

Answer 1

我认为条件 if (ddlInnoc.SelectedValue == string.Empty 不正确，因为 ddlInnoc.SelectedValue 的初始值将为 0 而不是 String.Empty..尝试将初始值检查为“0”

Answer 2

为了解决它添加的问题

if (ddlInnoc.SelectedValue != "0" && Session["pg1dd"] != null)
{
     ddlInnoc.SelectedValue = Session["pg1dd"].ToString();
}

ASP.Net 下拉列表不会重新显示我选择的选项

ASP.Net Dropdown List Doesn't Re-Display My Selected Option

html

asp.net

webforms