Definition and Usage
The RequiredFieldValidator control is used to make an input control a required field.
With this control, the validation fails if the input value does not change from its initial value. By default, the initial value is null.
Note: Leading and trailing spaces of the input value are removed before validation.
Note: The InitialValue property does not set the default value for the input control. It indicates the value that you do not want the user to enter in the input control.
Properties
| Property |
Value |
Description |
| Alignment |
left
center
right |
Optional. How to align the control |
| BackColor |
rgb(x,x,x)
#xxxxxx
colorname |
Optional. A background color for the control |
| ControlToValidate |
id_of_target_control |
Optional. The id of the control to validate |
| Display |
None
Static
Dynamic |
Optional. 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
Dynamic is default
|
| ErrorMessage |
errortext_for_summary |
Optional. The text to display in the ValidationSummary control when validation fails |
| ForeColor |
rgb(x,x,x)
#xxxxxx
colorname |
Optional. A foreground color for the control |
| Font-Bold |
false
true |
Optional. Specifies whether or not the text in the control should be bold |
| Font-Italic |
false
true |
Optional. Specifies whether or not the text in the control should be italic |
| Font-Name |
fontname |
Optional. Specifies the font name of the text in the control |
| Font-Size |
normal
small
large |
Optional. Specifies the font size of the text in the control |
| id |
unique_name |
Optional. A unique id for the control |
| InitialValue |
initial_value |
Optional. Specifies the starting value of the input control. Default value is null |
| runat |
"server" |
Required. Specifies that the control is a server control |
| StyleReference |
name_of_style_element |
Optional. Specifies a reference to a style to be applied to the control |
| Text |
errortext |
Optional. The message to display when validation fails |
| Wrapping |
wrap
nowrap |
Optional. Specifies whether or not the text in the control should wrap |
Example 1
The following example contains two forms in an .aspx file. The first form has a label with the text "Please enter a number from 1 through 100", an input box to input a number, a RangeValidator control that checks that the input value is a number from 1 through 100, a RequiredFieldValidator control that checks that the input field isn't empty, and a submit button. The second page is activated by the submit button on the first page, and displays a response. If the input value validates as an error, an error message is displayed:
<%@ Page
Inherits="System.Web.UI.MobileControls.MobilePage"%>
<%@ Register TagPrefix="Mobile"
Namespace="System.Web.UI.MobileControls"
Assembly="System.Web.Mobile" %>
<script runat="server">
sub page2(Sender as Object,E as EventArgs)
if Page.IsValid then
ActiveForm=f2
lbl2.Text="You entered number " & txt1.text
end if
end sub
</script>
<Mobile:Form id="f1" runat="server">
<Mobile:Label runat="server">
Please enter a number from 1 through 100
</Mobile:Label>
<Mobile:TextBox id="txt1" runat="server"/>
<Mobile:RangeValidator
ControlToValidate="txt1"
Type="Integer"
MaximumValue="100"
MinimumValue="1"
Text="Invalid number"
runat="server" />
<Mobile:RequiredFieldValidator
ControlToValidate="txt1"
Text="A number is required"
runat="server" />
<Mobile:Command runat="server"
OnClick="page2">Submit
</Mobile:Command>
</Mobile:Form>
<Mobile:Form id="f2" runat="server">
<Mobile:Label id="lbl2" runat="server" />
</Mobile:Form> |
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