ASP.NET RequiredFieldValidator Control
Definition and Usage
The RequiredFieldValidator control is used to make an input control a required field.
Through this control, the validation will fail if the initial value of the input is not changed. By default, the initial value is an empty string ("
Note:Leading and trailing spaces of the input value will be removed before validation.
Note:InitialValue does not set a default value for the input control. It indicates that youNot desiredThe value entered by the user in the input control.
Property
| Property | Description |
|---|---|
| BackColor | Background color of the RangeValidator control |
| ControlToValidate | The id of the control to be validated |
| Display |
Display behavior of the validation control. Valid values include:
|
| EnableClientScript | Boolean value specifying whether client-side validation is enabled. |
| Enabled | Boolean value specifying whether the validation control is enabled. |
| ErrorMessage |
Text displayed in the ValidationSummary control when validation fails. Note: If the Text property is not set, the text will also be displayed in the validation control. |
| ForeColor | The foreground color of the control. |
| id | The unique id of the control. |
| InitialValue | Specifies the initial value (starting value) of the input control. The default is "". |
| IsValid | Boolean value indicating whether the associated input control passes validation. |
| runat | Specifies that the control is a server control. Must be set to 'server'. |
| Text | Message displayed when validation fails. |
Example
- RequiredFieldValidator
- In this example, we declare two TextBox controls, one Button control, and one RequiredFieldValidator control in the .aspx file. It demonstrates how to use the RequiredFieldValidator control to make the 'txt_name' text box a required field.
