名称“”在当前上下文中不存在

Question

The name 'Label2.Text' does not exist in the current context Catalog.aspx

 <asp:DataList ID="DataList1" runat="server" DataKeyField="Id" DataSourceID="SqlDataSource1" RepeatColumns="4" RepeatLayout="Flow">
    <ItemTemplate>
        <div class="Item">
            <div class="name">
                <asp:Label ID="NameLabel" runat="server" Text='<%# Eval("Name") %>' />
            </div>
            <div>
                Код:<asp:Label ID="Label2" runat="server" Text='<%# Eval("Id") %>' />
            </div>
            <img src="<%# Eval("Image") %>" height="115" alt="item"/>
            <div class="price">
                Цена:

                <asp:Label ID="PriceLabel" runat="server" Text='<%# Eval("Price")%>' />p.
                <asp:Button ID="Button2" runat="server" ForeColor="Black" 
                    onclick="Button2_Click" Text="В КОРЗИНУ" />
            </div>
            <div class="desc">
                <asp:Label ID="DescriptionLabel" runat="server" Text='<%# Eval("Description") %>' />

            </div>
        </div>
    </ItemTemplate>
</asp:DataList>

Catalog.aspx.cs

sqlCon.Open();
SqlCommand cmd_SQL = new SqlCommand("INSERT INTO Cart(ClientId,ProductId,Amount) VALUES (@ClientId,@ProductId,@Amount)", sqlCon);
cmd_SQL.Parameters.Add("@ClientId", SqlDbType.NVarChar).Value =Membership.GetUser().ProviderUserKey.ToString();
cmd_SQL.Parameters.Add("@ProductId", SqlDbType.NVarChar).Value =Label2.Text;
cmd_SQL.Parameters.Add("@Amount", SqlDbType.NVarChar).Value = 1;

cmd_SQL.CommandType = CommandType.Text;
cmd_SQL.ExecuteNonQuery();

The name 'Label2.Text' does not exist in the current context

Answer 1

Your label is inside of an item template, which means you cannot just access it any old place on the page. If you want to gain access to the value inside the label, then you need to tie into one of the DataList events, such as OnItemCommand (if you wanted to access the value as the result of a command button click, for instance). You can use FindControl inside of the event handler to access the value. For example:

<asp:DataList runat="server" ID="test" OnItemCommand="test_ItemCommand">
    <ItemTemplate>
        <asp:Label runat="server" ID="Label2" Text="Test" />
    </ItemTemplate>
</asp:DataList>

---

protected void test_ItemCommand(object source, System.Web.UI.WebControls.DataListCommandEventArgs e)
{
    if (e.Item != null)
    {
        var label2 = e.Item.FindControl("Label2");

        if (label2 != null && label2 is Label)
        {
            var productID = ((Label)label2).Text;

            // now you have the contents of the label's text property
        }
    }
}