How to reuse custom validation logic in multiple fields from the same Domain

Question

I intend to use a custom validator to check for not null values in specific conditions in a domain class. The same check should run in more than one field. So I "factored" the validation closure and tried to pass it as a parameter to each validator key in the constraints clause.

String type
String description
String size

static constraints = {
    description(nullable:true, validator: notNullIfCustom)
    size(nullable:true, validator: notNullIfCustom)
}

def notNullIfCustom = { val, object ->
        if (object.type == 'custom' && ! val)
            return "must provide a value to field ${0} when type is custom"
}

Nevertheless, Grails throws a MissingPropertyException with the message 'No such property: notNullIfCustom for class... Possible solutions: notNullIfCustom'. If I just copy and paste the closure body to each validator entry inside the constraints clause, it runs as expected.

PS: I don't want to use a shared validator because I'm not actually sharing the validator between domain classes, but between fields within the same domain.

Answer 1

The constraints block is static, so your custom validators have to be too. Just change that to

static notNullIfCustom = { val, object ->
   ...
}