Importing Domain Constraints

Following DRY is at the heart of grails. While saving domain objects in our project, we used to copy the domain class constraints to the Command Objects (pretty ugly as it is), until we found that we can import constraints directly from the domain classses using importFrom() method in Grails 2.0

class VenueCO {
    String name
    String description
    Integer someExtraField
       
    String addressLine1
    String addressLine2
    String city
    String state
    String zip
   
    static constraints = {
        importFrom Venue
        importFrom GeographicAddress
        
        someExtraField(nullable: false)
    }
}

Not only does it import all the constraints from the User and GeographicAddress domain classes and apply them to our command object, but also ignores the constraints that don’t have corresponding properties in the command object.

Other variations of the importFrom() are:

importFrom User, include: ["lastName"]
importFrom User, include: [/.*Name/]   // imports all constraints that ended with 'Name'

Note: It works for grails 2 and above. For others there is a similar concept of shared constraints.

Cheers.
Imran Mir
imran[at]intelligrape[dot]com