You can use api:validate to throw an error if a required value is not provided.

Parameters

• item: The item that contains the attribute to be validated.
• attr: The attribute to be validated. If the attribute does not exist, an error is thrown.
• code: The error code to be thrown if validation fails. Default: “api:validate”.
• desc: The error description to be thrown if validation fails. By default a message is thrown that the specified attribute is required.

Examples

Throw a more specific message if the _query item does not contain the Id attribute:

<api:validate attr="_query.Id"   desc="The Id is required to delete."/>

See Also

• api:throw: Raise an error (exception) from within a script.