RequiredFieldvalidator

Question

如何使用dropdownlist的必填字段验证器？

我的下拉列表有

-日-

item1

item2

Answer 1

使用InitialValue属性作为您不希望选择的默认项目：

<asp:DropDownList ID="ddlItems" runat="server">
    <asp:ListItem Text="-Day-" Value="-Day-"></asp:ListItem>
    <asp:ListItem Text="Item 1" Value="Item 1"></asp:ListItem>
    <asp:ListItem Text="Item 2" Value="Item 2"></asp:ListItem>
</asp:DropDownList>

<asp:RequiredFieldValidator runat="server" ID="RequiredFieldValidator1" 
    ErrorMessage="Validation Message !" ControlToValidate="ddlItems" 
    InitialValue="-Day-"></asp:RequiredFieldValidator>

Answer 2

您可以使用这样的CompareValidator：

<asp:DropDownList ID="ddlItems" runat="server">
    <asp:ListItem Text="-Day-" Value="-1"></asp:ListItem>
    <asp:ListItem Text="Item 1" Value="Item 1"></asp:ListItem>
    <asp:ListItem Text="Item 2" Value="Item 2"></asp:ListItem>
</asp:DropDownList>

<asp:CompareValidator runat="server" ID="CompareFieldValidator1" 
    ErrorMessage="Validation Message !" ControlToValidate="ddlItems" 
    ValueToCompare="-1" Operator="NotEqual"></asp:CompareValidator>

-Edoode