如果条件为必需的字段验证

Posted 2021-05-05

我在c＃.net中有一个DropDownList和一个TextBox。如果DropDownList值为“No”，则必须在TextBox中输入一些值。如果dropdownlist值为yes，那么TextBox不需要字段验证器。如何使它成为可能？

<asp:DropDownList ID="dropdownlist1" runat="server"
    CssClass="NormalText" Width="155px" AutoPostBack="true"
    onselectedindexchanged="ddls_SelectedIndexChanged">
    <asp:ListItem Selected="True" Value=""></asp:ListItem>    
    <asp:ListItem Value="Yes">Yes</asp:ListItem>
    <asp:ListItem Value="No">No</asp:ListItem>
</asp:DropDownList>
<br />
<br />
<asp:TextBox ID="Textbox1" runat="server" CausesValidation="True"></asp:TextBox>
&nbsp;
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server"
    ControlToValidate="Textbox1" ErrorMessage="Explanation needed If you select NO">
</asp:RequiredFieldValidator>
</td>


protected void dropdownlist1_SelectedIndexChanged(object sender, EventArgs e)
{
}

答案

使用此代码进行条件验证：

protected void dropdownlist1_SelectedIndexChanged(object sender, EventArgs e)
{
    if(dropdownlist1.SelectedValue == "No")
    {
       RequiredFieldValidator1.Enabled = true;
    }
    else if(dropdownlist1.SelectedValue == "Yes")
    {
       RequiredFieldValidator1.Enabled = false;
    }
}

或者，您可能还需要设置“提交按钮验证”组：

 ButtonSubmit.ValidationGroup = string.Empty;

何时未启用字段验证程序。