Validation Server Controls->ASP.NET CompareValidator Control

Definition and Usage

The CompareValidator control is used to compare the value of one input control to the value of another input control or to a fixed value.

Note: If the input control is empty, the validation will succeed. Use the RequiredFieldValidator control to make the field required.

Properties

Property Description
BackColor The background color of the CompareValidator control
ControlToCompare The name of the control to compare with
ControlToValidate The id of the control to validate
Display The display behavior for the validation control. Legal values are:
  • None (the control is not displayed. Used to show the error message only in the ValidationSummary control)
  • Static (the control displays an error message if validation fails. Space is reserved on the page for the message even if the input passes validation.
  • Dynamic (the control displays an error message if validation fails. Space is not reserved on the page for the message if the input passes validation
EnableClientScript A Boolean value that specifies whether client-side validation is enabled or not
Enabled A Boolean value that specifies whether the validation control is enabled or not
ErrorMessage The text to display in the ValidationSummary control when validation fails. Note: This text will also be displayed in the validation control if the Text property is not set
ForeColor The foreground color of the control
id A unique id for the control
IsValid A Boolean value that indicates whether the control specified by ControlToValidate is determined to be valid
Operator The type of comparison to perform. The operators are:
  • Equal
  • GreaterThan
  • GreaterThanEqual
  • LessThan
  • LessThanEqual
  • NotEqual
  • DataTypeCheck
runat Specifies that the control is a server control.  Must be set to "server"
Text The message to display when validation fails
Type

Specifies the data type of the values to compare. The types are:

  • Currency
  • Date
  • Double
  • Integer
  • String
ValueToCompare A specified value to compare with

Examples

CompareValidator
ASPX Source:

<html>
<body>

<form runat="server">
<table border="0" bgcolor="#b0c4de">
   <tr valign="top">
     <td colspan="4"><h4>Compare two values</h4></td>
   </tr>
   <tr valign="top">
     <td><asp:TextBox id="txt1" runat="server" /></td>
     <td> = </td>
     <td><asp:TextBox id="txt2" runat="server" /></td>
     <td><asp:Button Text="Validate" runat="server" /></td>
   </tr>
</table>
<br />
<asp:CompareValidator
id="compval"
Display="dynamic"
ControlToValidate="txt1"
ControlToCompare="txt2"
ForeColor="red"
BackColor="yellow"
Type="String"
EnableClientScript="false"
Text="Validation Failed!"
runat="server" />
</form>

</body>
</html>

Output Result:

Compare two values
=
 

If you enter "shaohai" in the first textbox ,and enter "konghua" into the second textbox ,if will show:

Compare two values
=

Validation Failed!
 

If you enter "shaohai" in the first textbox ,and enter "shaohai" into the second textbox ,if will show:

Compare two values
=
 

In this example we declare two TextBox controls, one Button control, and one CompareValidator control in an .aspx file. If validation fails, the text "Validation Failed!" will be displayed in red on a yellow background in the CompareValidator control.

CompareValidator 2
ASPX Source:

<script  runat="server">
sub check_operator(sender As Object, e As EventArgs)
   compval.Operator=CType(list.SelectedIndex,ValidationCompareOperator)
   compval.Validate()
end sub
</script>

<html>
<body>

<form runat="server">
<table border="0" bgcolor="#b0c4de">
   <tr valign="top">
     <td colspan="4"><h4>Compare two values</h4></td>
   </tr>
   <tr valign="top">
     <td><asp:TextBox id="txt1" runat="server" /></td>
     <td>
     <asp:ListBox id="list" rows="2" OnSelectedIndexChanged="check_operator" runat="server">
           <asp:ListItem value="Equal" selected>=</asp:ListItem>
           <asp:ListItem value="NotEqual"><></asp:ListItem>
     </asp:ListBox>
     </td>
     <td><asp:TextBox id="txt2" runat="server" /></td>
     <td><asp:Button Text="Validate" runat="server" /></td>
   </tr>
</table>
<br />
<asp:CompareValidator
id="compval"
Display="dynamic"
ControlToValidate="txt1"
ControlToCompare="txt2"
ForeColor="red"
BackColor="yellow"
Type="String"
EnableClientScript="false"
Text="Validation Failed!"
runat="server" />
</form>

</body>
</html>

Output Result:

Compare two values
 

If you enter "shaohai" in the first textbox ,and enter "konghua" into the second textbox ,if will show:

Compare two values

Validation Failed!

If you enter "shaohai" in the first textbox ,and enter "konghua" into the second textbox ,if will show:

Compare two values
 

If you enter "shaohai" in the first textbox ,and enter "shaohai" into the second textbox ,if will show:

Compare two values
 

If you enter "shaohai" in the first textbox ,and enter "shaohai" into the second textbox ,if will show:

Compare two values

Validation Failed!  

In this example we declare two TextBox controls, one ListBox control, one Button control, and one CompareValidator control in an .aspx file. The check_operator() function sets the operator of the CompareValidator control equal to the selected operator in the ListBox control, then it validates the CompareValidator control. If validation fails, the text "Validation Failed!" will be displayed in red on a yellow background in the CompareValidator control.

posted on 2007-03-28 16:12  改变热爱  阅读(232)  评论(0)    收藏  举报

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