使用asp.net验证控件验证DropDownList [英] Validate a DropDownList using asp.net validation controls

问题描述

在下面的下拉菜单中，如果我选择 value = - 1，它会显示一条消息，例如

请选择课程它应该不接受第一个值。

 <   p  >  
 <   asp：标签    ID   =  lblcourses    runat   =  server   文字  = 课程名称 >  <   / asp：标签 >  
 <   asp：DropDownList     ID   =  drpcourses    runat   = 服务器 >  
  <   asp：ListItem    文字  =    值  =  -1 >  <   / asp：ListItem  >   
 <   asp：ListItem    文本  = 基本Unix    Value   =  1 >  <   / asp：ListItem  >  
 <   asp：ListItem    文本  = 基本Oracle   值  =  2 >  <   / asp：ListItem  >  
 <   asp：ListItem     Text   =  PL / SQL   值  =  3  >  <   / asp：ListItem  >  
 <   asp：ListItem    文本  =  Oracle 11g DBA   值 < span class =code-keyword> =  4 >  <   / asp：ListItem  >  
 <   asp：ListItem    文本  =  Oracle 11g DBA F / T   值  =  5 >  <   / asp：ListItem  >  
 <   asp：ListItem    文本  =  Oracle 11g RAC F / T   值  =  6 >  <   / asp：ListItem  >  
 <   asp：ListItem    文本  =  Linux Admin   值  =   7 >  <   / asp：ListItem  >  
 <   asp：ListItem    文本  =  Unix管理   值  =  8 >  <   / asp：ListItem  >  
 <   asp ：ListItem    文本  =  Advance Shell   值  =  9 >  <   / asp：ListItem  >  
 <   asp：ListItem    文字  =  Hadoop管理   值  =   1 >  <   / asp：ListItem  >  
 <   / asp：DropDownList  >  
 <   asp：RequiredFieldValidator    < span class =code-attribute> ID   =  rfvcourses    runat   =  server    controltovalidate   =  drpcourses    ErrorMessage   = 选择课程 >  <   / asp：RequiredFieldValidator  >  
 <   / p  >  
 
 <   p  >  
 < ;   asp：按钮    ID   =  btnsave    runat   =  server     文字  = 添加  /  >  
 <   / p  >  
 

解决方案

你需要添加 InitialValue = - 1

 <   asp：requiredfieldvalidator     id   =  rfvcourses    runat   =  server    initialvalue   =   -  1    controltovalidate   =  drpcourses    errormessage   = 选择课程 >  <   / asp：requiredfieldvalidator  >  

RequiredFieldValidator.InitialValue Property [< a href =http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.requiredfieldvalidator.initialvalue(v=vs.110).aspx\"target =_ blanktitle =New窗口> ^ ]

< asp：dropdownlist id =   ddlDesignation runat =   server xmlns ：asp =  ＃unknown >  < /   asp：dropdownlist  >  
 
 
< asp：requiredfieldvalidator id =   RequiredFieldValidator3 runat =  服务器 controltovalidate =   ddlDesignation xmlns：asp =  ＃unknown >  
 ErrorMessage =  请选择您的名称。 ValidationGroup =   提交   InitialValue =    -  1   SetFocusOnError =   True CssClass =  验证者 >  < /   asp：requiredfieldvalidator  >  

In the below dropdown if i select value="-1" it will show a message like
Please select a course It should not accept the First value.

<p>
   <asp:Label ID="lblcourses" runat="server" Text="Course Name"></asp:Label>
   <asp:DropDownList ID="drpcourses" runat="server">
  <asp:ListItem Text="" Value="-1"></asp:ListItem>
   <asp:ListItem Text="Basic Unix" Value="1"></asp:ListItem>
   <asp:ListItem Text="Basic Oracle" Value="2"></asp:ListItem>
   <asp:ListItem Text="PL/SQL" Value="3"></asp:ListItem>
   <asp:ListItem Text="Oracle 11g DBA" Value="4"></asp:ListItem>
   <asp:ListItem Text="Oracle 11g DBA F/T" Value="5"></asp:ListItem>
   <asp:ListItem Text="Oracle 11g RAC F/T" Value="6"></asp:ListItem>
   <asp:ListItem Text="Linux Admin" Value="7"></asp:ListItem>
   <asp:ListItem Text="Unix Administration" Value="8"></asp:ListItem>
   <asp:ListItem Text="Advance Shell" Value="9"></asp:ListItem>
   <asp:ListItem Text="Hadoop Administration" Value="1"></asp:ListItem>
   </asp:DropDownList>
   <asp:RequiredFieldValidator ID="rfvcourses" runat="server" controltovalidate="drpcourses" ErrorMessage="Select a Course"></asp:RequiredFieldValidator>
   </p>

 <p>
 <asp:Button ID="btnsave" runat="server"  Text="Add"/>
 </p>

解决方案

you need to add InitialValue="-1"

<asp:requiredfieldvalidator id="rfvcourses" runat="server" initialvalue="-1" controltovalidate="drpcourses" errormessage="Select a Course"></asp:requiredfieldvalidator>

RequiredFieldValidator.InitialValue Property[^]

<asp:dropdownlist id="ddlDesignation" runat="server" xmlns:asp="#unknown"></asp:dropdownlist>
                            
                       
<asp:requiredfieldvalidator id="RequiredFieldValidator3" runat="server" controltovalidate="ddlDesignation" xmlns:asp="#unknown">
ErrorMessage="Please select your designation." ValidationGroup="submit" InitialValue="-1" SetFocusOnError="True" CssClass="Validators"></asp:requiredfieldvalidator>

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