<Validate Type="Required">

The Required validator prevents the form from being submitted if its target control is empty. It's the most commonly used validator — drop it next to any control that the user must fill in.

Not for checkboxes

A <CheckBox> always has a value (checked or unchecked), and a <CheckBoxList> is treated similarly — so Type="Required" doesn't do what you'd expect on those. Use <Validate Type="Checkbox"> to require a single checkbox to be checked, or <Validate Type="CheckboxList"> to require at least one item in a list to be selected.

Example

<AddForm>
  <SubmitCommand CommandText="INSERT INTO Users(FirstName, LastName) VALUES(@FirstName, @LastName)" />
  <table>
    <tr>
      <td>
        <Label For="txtFirstName" Text="First Name" />
        <TextBox Id="txtFirstName" DataField="FirstName" DataType="string" />
        <Validate Type="Required" Target="txtFirstName"
                  Message="You must enter a First Name" />
      </td>
    </tr>
    <tr>
      <td>
        <Label For="txtLastName" Text="Last Name" />
        <TextBox Id="txtLastName" DataField="LastName" DataType="string" />
      </td>
    </tr>
    <tr>
      <td colspan="2">
        <AddButton Text="Add" />&nbsp;<CancelButton Text="Cancel" />
        <ValidationSummary />
      </td>
    </tr>
  </table>
</AddForm>

Properties

Property	Values	Default	Description
Type *	Required		Identifies this as a Required validator
Target *	control ID		ID of the control to validate
CssClass	string		CSS class name(s) for styling the validator's error display
Display	Static Dynamic	Dynamic	Whether the validator reserves layout space when no error is shown
EnableClientScript	True False	True	When True, validation runs in the browser as well as on the server
Height	size		Height of the validator's error display
Message	string		Text shown in the <ValidationSummary> when validation fails
Text	string		Text shown inline at the validator's location when validation fails. Often a short marker (e.g. * or **)
Width	size		Width of the validator's error display

* Required property

Deprecated Properties

These properties use ASP.NET inline styling and are no longer recommended for modern web development. Use the CssClass property to apply CSS classes or the Style property for inline CSS instead.

Property	Values	Description
BackColor	color name | #dddddd	Background color of the validator's error display
BorderColor	color name | #dddddd	Border color
BorderStyle	NotSet None Dotted Dashed Solid Double Groove Ridge Inset Outset	Border style
BorderWidth	size	Border width
Font-Bold	True False	Bold text
Font-Italic	True False	Italic text
Font-Names	string	Font family name
Font-Overline	True False	Overline text decoration
Font-Size	XX-Small X-Small Small Medium Large X-Large XX-Large or size	Font size
Font-Strikeout	True False	Strikethrough text decoration
Font-Underline	True False	Underline text decoration
ForeColor	color name | #dddddd	Text color. Note: the validator hard-codes red, bold text by default. If you set CssClass, XMP automatically clears ForeColor so your stylesheet's color rules take effect

Property Details

• Type: Set to Required to identify this as a Required validator. The single <Validate> tag supports many validator types via this attribute (see Compare, Range, Email, RegEx, and others).

• Target: The ID of the form control whose value should be checked. Maps to ASP.NET's ControlToValidate.

• Message: The error text shown in the <ValidationSummary> (if you have one) when validation fails. If no <ValidationSummary> is present, this text appears at the validator's location instead.

• Text: The text shown inline at the validator's location when validation fails. Used together with Message and <ValidationSummary>: a short inline marker (*, **, or an icon) at the validator + the full sentence in the summary block.

• Display: Whether the validator reserves layout space even when no error is shown. Dynamic (the default) collapses to no space until validation fails — usually what you want. Static always reserves space (useful when you want the form layout to not shift when an error appears).

• EnableClientScript: When True (the default), the validator runs in the browser before the form is submitted, giving the user immediate feedback. Set to False to force server-side-only validation — useful for controls (like rich text editors) that don't expose their value cleanly to client-side script.