Built-in Field Validator plugins

Name	Interface	Description
SampleFormFieldValidator	FieldValidator	Example single-field validator: rejects a value longer than 3 characters. Not tied to any particular metadata field - intended as a copy-paste starting point for a new FieldValidator implementation.
SampleFormFieldCheckValidator	FieldValidator	Example single-field validator for a checkbox-like field: requires the value to be exactly “true”.

Note

Neither of the two is wired to a metadata field automatically - each is referenced by canonical class name from the metadata field’s validator type=“plugin” element in the metadata XML definition. See Creating your own Form Validator plugin for the full XML example.