Question

我是一名新的ASP.NET开发人员，我现在正在努力解决以下问题;我有一个具有多个GridView的面板控件。根据DropDownList中的选择，只显示一个GridView。

让我们假设我们有三个GridView，我们有一个带有三个选项的DropDownList; A，B和C.如果选择A，将显示第一个GridView。之后，如果我选择B，除了第一个显示的GridView之外，还将显示第二个GridView。我想要的是从下拉列表中选择任何选项后，应删除GridView和Label控件并替换为新结果。

那我怎么能这样做？

我的ASP.NET代码：

    <asp:Panel ID="Panel1" runat="server">
            <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
<asp:ListItem>Please Select</asp:ListItem>
                <asp:ListItem>A</asp:ListItem>
                <asp:ListItem>B</asp:ListItem>
                <asp:ListItem>C</asp:ListItem>
            </asp:DropDownList>
            <br /><br />
            <asp:GridView ID="GridView1" runat="server" Visible="true"></asp:GridView>
            <br />
            <asp:GridView ID="GridView2" runat="server" Visible="true"></asp:GridView>
            <br />
            <asp:GridView ID="GridView3" runat="server" Visible="true"></asp:GridView>
            <br /><br />
            <asp:Label ID="lblMessage" runat="server" Text=""></asp:Label>
        </asp:Panel>

C＃代码：

 protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (DropDownList1.SelectedIndex != null)
        {
            int option = DropDownList1.SelectedIndex;

            var myList2 = new List<string>();
            myList2.Add("Test");
            myList2.Add("Test");

            var myList3 = new List<string>();

            switch (option)
            {
                case 1:
                    if (myList2.Count > 0)
                    {
                        GridView1.DataSource = myList2;
                        GridView1.DataBind();
                        GridView1.Visible = true;
                    }
                    else
                    {
                        lblMessage.BackColor = System.Drawing.Color.Yellow;
                        lblMessage.ForeColor = System.Drawing.Color.Red;
                        lblMessage.Text = "No Data!";
                    }
                    break;
                case 2:
                    if (myList3.Count > 0)
                    {
                        GridView1.Visible = false;
                        GridView2.DataSource = myList3;
                        GridView2.DataBind();
                        GridView2.Visible = true;
                    }
                    else
                    {
                        lblMessage.BackColor = System.Drawing.Color.Yellow;
                        lblMessage.ForeColor = System.Drawing.Color.Red;
                        lblMessage.Text = "No Data!";
                    }
                    break;
                case 3: 
                    if (myList2.Count > 0)
                    {
                        GridView1.Visible = false;
                        GridView2.Visible = false;
                        GridView3.DataSource = myList2;
                        GridView3.DataBind();
                        GridView3.Visible = true;
                    }
                    else
                    {
                        lblMessage.BackColor = System.Drawing.Color.Yellow;
                        lblMessage.ForeColor = System.Drawing.Color.Red;
                        lblMessage.Text = "No Data!";
                    }
                    break;
                default:
                    break;
            }
        }
    }

注意：正如你在上面的C＃中看到的那样，在switch语句的每种情况下，我都删除了前面案例的控件，但这不是正确的方法，因为我需要在选择后删除GridView或Label控件下拉列表中的任何项目。那么有什么方法可以解决这个问题。

Answer 1

按照此处所述使用MultiView控件：

像这样更改页面：

<asp:Panel ID="Panel1" runat="server">
        <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
            <asp:ListItem>Please Select</asp:ListItem>
            <asp:ListItem>A</asp:ListItem>
            <asp:ListItem>B</asp:ListItem>
            <asp:ListItem>C</asp:ListItem>
        </asp:DropDownList>
        <br /><br />
        <asp:MultiView ID="MainMultiview" runat="server">
        <asp:View ID="View1" runat="server">
            GridView 1
            <asp:GridView ID="GridView1" runat="server" Visible="true"></asp:GridView>
            <br />
        </asp:View>
        <asp:View ID="View2" runat="server">
            GridView 2
            <asp:GridView ID="GridView2" runat="server" Visible="true"></asp:GridView>
            <br />
        </asp:View>
        <asp:View ID="View3" runat="server">
            GridView 3
            <asp:GridView ID="GridView3" runat="server" Visible="true"></asp:GridView>
            <br />
        </asp:View>
        </asp:MultiView>
        <br />
        <asp:Label ID="lblMessage" runat="server" Text=""></asp:Label>
    </asp:Panel>

并将C＃类后面的代码更改为：

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (DropDownList1.SelectedIndex != null)
        {
            int option = DropDownList1.SelectedIndex;

            var myList2 = new List<string>();
            myList2.Add("Test");
            myList2.Add("Test");

            var myList3 = new List<string>();

            switch (option)
            {
                case 1:
                    if (myList2.Count > 0)
                    {
                        //GridView1.DataSource = myList2;
                        //GridView1.DataBind();
                        //GridView1.Visible = true;
                        MainMultiview.SetActiveView(View1);
                    }
                    else
                    {
                        lblMessage.BackColor = System.Drawing.Color.Yellow;
                        lblMessage.ForeColor = System.Drawing.Color.Red;
                        lblMessage.Text = "No Data!";
                    }
                    break;
                case 2:
                    if (myList2.Count > 0)
                    {
                        //GridView1.Visible = false;
                        //GridView2.DataSource = myList3;
                        //GridView2.DataBind();
                        //GridView2.Visible = true;
                        MainMultiview.SetActiveView(View2);
                    }
                    else
                    {
                        lblMessage.BackColor = System.Drawing.Color.Yellow;
                        lblMessage.ForeColor = System.Drawing.Color.Red;
                        lblMessage.Text = "No Data!";
                    }
                    break;
                case 3:
                    if (myList2.Count > 0)
                    {
                        //GridView1.Visible = false;
                        //GridView2.Visible = false;
                        //GridView3.DataSource = myList2;
                        //GridView3.DataBind();
                        //GridView3.Visible = true;
                        MainMultiview.SetActiveView(View3);
                    }
                    else
                    {
                        lblMessage.BackColor = System.Drawing.Color.Yellow;
                        lblMessage.ForeColor = System.Drawing.Color.Red;
                        lblMessage.Text = "No Data!";
                    }
                    break;
                default:
                    break;
            }
        }
    }

注意gridview无法绑定到字符串列表。但多视图的工作很有意义。

如何从DropDownList中选择每个选项后删除面板中显示的控件？

1 个答案: