<Validate Type="Checkbox">

The Checkbox validator prevents the form from being submitted unless the target <Checkbox> is in the required state. The classic case is a "I agree to the terms" checkbox that the user must tick — but the validator can also require a checkbox to be unchecked via MustBeChecked="False".

Why not Validate Type="Required"?

A checkbox always has a value (it's either checked or unchecked), so a "required" check would always pass. The Checkbox validator exists specifically to express "this checkbox must be in this state."

Example

<AddForm>
  <SubmitCommand CommandText="INSERT INTO Users(FirstName, LastName, Agree)
                              VALUES(@FirstName, @LastName, @Agree)" />
  <table>
    <tr>
      <td>
        <Label For="txtFirstName" Text="First Name" />
        <TextBox Id="txtFirstName" DataField="FirstName" DataType="string" />
      </td>
    </tr>
    <tr>
      <td>
        <Label For="chkAgree" Text="I agree to the Terms of Service" />
        <Checkbox Id="chkAgree" DataField="Agree" DataType="boolean" />
        <Validate Type="Checkbox" Target="chkAgree" MustBeChecked="True"
                  Message="You must agree to the terms" />
      </td>
    </tr>
    <tr>
      <td colspan="2">
        <AddButton Text="Add" />&nbsp;<CancelButton Text="Cancel" />
        <ValidationSummary />
      </td>
    </tr>
  </table>
</AddForm>

Properties

Property	Values	Default	Description
Type *	Checkbox		Identifies this as a Checkbox validator
Target *	control ID		ID of the <Checkbox> to validate
MustBeChecked	True False	True	The state the checkbox must be in to pass validation
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
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 of the error display

Property Details

• Type: Set to Checkbox to identify this as a Checkbox validator.

• Target: The ID of the <Checkbox> control whose state should be checked. The control must be a <Checkbox> — the validator throws an exception at runtime if pointed at any other control type.

• MustBeChecked: The state the checkbox must be in to pass validation. True (the default) means the box must be checked; False means it must be unchecked.

• 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. Static always reserves space.

• EnableClientScript: When True (the default), the validator runs in the browser as well as on the server. The check is implemented as a small JavaScript expando attribute that mirrors MustBeChecked, so the user gets immediate feedback without a postback.