Check form input value and report error in case of empty input (VB.net) : TextBox « ASP.net Controls « ASP.NET Tutorial






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  2. ASP.net Controls
  3. TextBox
<%@ Page Language="VB" %>

<script runat="server">
   sub Submit(Sender as Object, e as EventArgs)
      lblMessage.Text = ""

      if tbName.Text = "" then
         lblMessage.Text = "You forgot your name!<br>"
      end if
      if tbPhone.Text = "" then
         lblMessage.Text += "You forgot your phone!<br>"
      end if
      if tbEmail.Text = "" then
         lblMessage.Text += "You forgot your email!<br>"
      end if
      
      if lblMessage.Text = "" then
         lblMessage.Text = "Your information has been " & _
            "submitted!"
      end if
      
      
   end sub
</script>

<html><body>
   Please enter the following information.
   <asp:Label id="lblMessage" runat="server"/>
   <form runat="server">
      <table>
      <tr>
         <td width="250">Name* </td>
         <td width="150">
            <asp:TextBox id="tbName" runat="server"/>
         </td>
      </tr>
      <tr>
         <td>Address</td>
         <td>
            <asp:TextBox id="tbAddress" runat="server"/>
         </td>
      </tr>
      <tr>
         <td>Phone* (area code first)</td>
         <td>
            <asp:TextBox id="tbPhone" runat="server"/>
         </td>
      </tr>
      <tr>
         <td>Fax (area code first)</td>
         <td>
            <asp:TextBox id="tbFax" runat="server"/>
         </td>
      </tr>
      <tr>
         <td>Email*</td>
         <td>
            <asp:TextBox id="tbEmail" runat="server"/>
         </td>
      </tr>
      <tr>
         <td colspan="2">
            <asp:Button id="btSubmit" runat="server" Text="Submit" OnClick="Submit" />
         </td>
      </tr>
      </table>
      
      <i>An asterisk (*) indicates a required field.</i>
   </form>
</body></html>








3.5.TextBox
3.5.1.Important properties, method and event of TextBox control
3.5.2.TextBox can display different types of input fields depending TextMode property
3.5.3.Show AutoComplete
3.5.4.Set the focus to a TextBox
3.5.5.Get input value from asp:textbox (VB.net)
3.5.6.Set textbox text value in button action
3.5.7.asp:TextBox changed event (C#)
3.5.8.Use if statement to check form input data (VB.net)
3.5.9.Bind string value to asp:textBox (VB.net)
3.5.10.Use Cint to convert input value in asp:textbox to integer (VB)
3.5.11.Use Convert.ToInt32 to convert input value in asp:textbox to integer (C#)
3.5.12.Check form input value and report error in case of empty input (VB.net)
3.5.13.Set AutoCompleteType
3.5.14.Convert input in TextBox into decimal
3.5.15.Extrapolate date values from the typed text