如何检查至少一个单选按钮列表已经项选择？ [英] How to check that at least one RadioButtonList has an item selected?

问题描述

我有20 单选按钮列表个页面上。

我需要创建一个验证方法，以确保这些至少有一个单选按钮列表 S有选择的项目。

I need to create a validation method to ensure that at least one of these RadioButtonLists has an item selected.

我将需要使用这个什么样的验证？

What kind of validation would I need to use for this?

推荐答案

编辑：根据意见和澄清问题，更新

Updated question based on comments and clarification.

如果您要验证针对多个单选按钮列表 s然后需要使用的CustomValidator 并实现服务器端检查

If you are validating against multiple RadioButtonLists then you need to use a CustomValidator and implement the server side check.

下面是一些测试标记：

<asp:RadioButtonList ID="rblstTest1" runat="server" ValidationGroup="Test">
    <asp:ListItem Text="Test 1" Value="1" />
    <asp:ListItem Text="Test 2" Value="2" />
    <asp:ListItem Text="Test 3" Value="3" />
</asp:RadioButtonList>
<br /><br />
<asp:RadioButtonList ID="rblstTest2" runat="server" ValidationGroup="Test">
    <asp:ListItem Text="Test 1" Value="1" />
    <asp:ListItem Text="Test 2" Value="2" />
    <asp:ListItem Text="Test 3" Value="3" />
</asp:RadioButtonList><br />
<asp:Button ID="btnTestRb" runat="server" ValidationGroup="Test" Text="Test RBL" 
    OnClick="btnTestRb_Click" />
<asp:CustomValidator runat="server" ValidationGroup="Test" ID="cvTest" 
    ControlToValidate="rblstTest1" OnServerValidate="cvTest_ServerValidate" 
    ValidateEmptyText="true" Enabled="true" display="Dynamic" SetFocusOnError="true"
    ErrorMessage="You must select at least one item." /> 

使用下面的扩展方法来发现所有的单选按钮列表控件（来源）

Use the following extension method to find all the RadioButtonList controls (Source):

static class ControlExtension
{
    public static IEnumerable<Control> GetAllControls(this Control parent)
    {
        foreach (Control control in parent.Controls)
        {
            yield return control;
            foreach (Control descendant in control.GetAllControls())
            {
                yield return descendant;
            }
        }
    }
} 

然后实现服务器端的CustomValidator 检查：

protected void cvTest_ServerValidate(object sender, ServerValidateEventArgs e)
{            
    int count = this.GetAllControls().OfType<RadioButtonList>().
        Where(lst => lst.SelectedItem != null).Count();
    e.IsValid = (count > 0);
 }

我已经测试上面的例子中，它似乎做的正是你所需要的。你应该能够将其轻松地切换到VB pretty。希望这会解决您的问题。

I have tested the above example and it seems to do exactly what you need. You should be able to switch it to VB pretty easily. Hope this solves your problem.

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