RequiredFieldValidator不适用于Dropdownlist [英] RequiredFieldValidator not working for Dropdownlist

问题描述

我的网页中有一个 Dropdownlist ，如下所示.

I have a Dropdownlist in my web page as follows.

<asp:DropDownList runat="server" ID="cboNoOfSubjects" AutoPostBack="true" CssClass="textEntry"  width="80%" onclick="javascript:shouldsubmit=false;" ValidationGroup="valCourseFees">
   <asp:ListItem Value="0">-Select-</asp:ListItem>
   <asp:ListItem Value="1">1</asp:ListItem>
   <asp:ListItem Value="2">2</asp:ListItem>
   <asp:ListItem Value="3">3</asp:ListItem>
   <asp:ListItem Value="4">4</asp:ListItem>
   <asp:ListItem Value="5">5</asp:ListItem>
</asp:DropDownList>
    <font color ="red">*</font> 

<asp:RequiredFieldValidator ID="cboNoOfSubjects_RequiredFieldValidator" 
 runat="server" ErrorMessage="No. of Subjects Required" ForeColor="Red"
 Font-Size="0.9em" ControlToValidate="cboNoOfSubjects" 
ValidationGroup="valCourseFees" Display="None"></asp:RequiredFieldValidator>

但是验证器似乎没有触发.有人可以帮我吗?

But the validator does not seem to fire. Can anyone help me with this?

推荐答案

对于所有RequiredFieldValidators，

For all RequiredFieldValidators, the InitalValue property is important. Add it to yours and it will work.

<asp:RequiredFieldValidator ID="cboNoOfSubjects_RequiredFieldValidator" runat="server"  
 ErrorMessage="No. of Subjects Required" ForeColor="Red" InitialValue="0"
 Font-Size="0.9em" ControlToValidate="cboNoOfSubjects" 
 ValidationGroup="valCourseFees" Display="None"></asp:RequiredFieldValidator>

要更改的另一件事，您必须设置属性Display ="Dynamic"，该属性将相应显示.

One thing more to change, you have to set the property Display="Dynamic" which will display accordingly.

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