一个多选题限制最多只能选N个,CheckBoxList 如何判断

最新推荐文章于 2020-08-25 09:50:14 发布

转载最新推荐文章于 2020-08-25 09:50:14 发布 · 1.5k 阅读

文章标签：

#dataset #server #asp #database #object #html

本文介绍如何使用ASP.NET中的CheckBoxList控件实现多选题最多选择三个选项的功能，并展示了具体的实现代码。

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一个多选题限制最多只能选N个,CheckBoxList 如何判断

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>无标题页</title>
</head>
<body>
    <form id="form1" runat="server">
    <asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
    <div>
        <asp:DataList ID="DataList1" runat="server" RepeatLayout="Flow">
        <ItemTemplate>
            <%#Eval("OrderID") %>
            <asp:UpdatePanel ID="UpdatePanel1" runat="server" ChildrenAsTriggers="False" RenderMode="Inline" UpdateMode="Conditional">
                <ContentTemplate>
                    <asp:CheckBoxList ID="CheckBoxList1" runat="server" DataSource='<%# GetOrderDetails(Convert.ToInt32(Eval("OrderID"))) %>' DataTextField="UnitPrice" DataValueField="ProductID" RepeatLayout="Flow" RepeatDirection="Horizontal" AutoPostBack="True" OnSelectedIndexChanged="CheckBoxList1_SelectedIndexChanged">
                    </asp:CheckBoxList>
                </ContentTemplate>
            </asp:UpdatePanel>
        </ItemTemplate>
        </asp:DataList>
        <asp:UpdatePanel ID="UpdatePanel2" runat="server" ChildrenAsTriggers="False" RenderMode="Inline" UpdateMode="Conditional">
        <ContentTemplate>
        <asp:Label ID="Label1" runat="server"></asp:Label>
        </ContentTemplate>
        </asp:UpdatePanel>
     </div>
    </form>
</body>
</html>

private void BindDataList()
{
    SqlConnection cn = new SqlConnection(@"server=./SQLExpress;uid=sa;pwd=;database=Northwind");
    SqlDataAdapter da = new SqlDataAdapter("select top 10 orderid, CustomerID, OrderDate from Orders", cn);
    DataSet ds = new DataSet();
    cn.Open();
    da.Fill(ds);
    cn.Close();
    DataList1.DataSource = ds.Tables[0].DefaultView;
    DataList1.DataBind();
}

protected DataTable GetOrderDetails(int orderID)
{
    SqlConnection cn = new SqlConnection(@"server=./SQLExpress;uid=sa;pwd=;database=Northwind");
    SqlDataAdapter da = new SqlDataAdapter("select ProductID, UnitPrice from [Order Details] where orderid = @orderid", cn);
    da.SelectCommand.Parameters.AddWithValue("@orderid", orderID);
    DataSet ds = new DataSet();
    cn.Open();
    da.Fill(ds);
    cn.Close();
    return ds.Tables[0];
}

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        BindDataList();
    }
}

protected void CheckBoxList1_SelectedIndexChanged(object sender, EventArgs e)
{
    CheckBoxList chk = sender as CheckBoxList;
    int count = 0;
    foreach (ListItem li in chk.Items)
    {
        if (li.Selected)
        {
            count++;
            if (count >= 3)
            {
                Label1.Text = "Wrong";
                UpdatePanel2.Update();
                break;
            }
            else
            {
                Label1.Text = string.Empty;
                UpdatePanel2.Update();
            }
        }
    }
    ((UpdatePanel)((DataListItem)chk.NamingContainer).FindControl("UpdatePanel1")).Update();
}