Grails domain constraints definition

Question

Hi!

I have a Grails application with a -simplified - domain class which looks like this:

class Capacity {

static constraints = {              
    month(blank:false, nullable:false)
    company(blank:false, nullable:false)
}


Date month    
Company company
String note
...
}

The pair month-company must be unique. (I.e. they should be primary key at the DB).

How can I define such a constraint?

Thanks a lot in advance

Luis

Answer 1

Since you want this to be a composite primary key in the DB you will have to declare that mapping:

class Capacity implements Serializable {
    Date month    
    Company company
    String note
    ...

    static mapping = { 
        id composite:['month', 'company'] 
    } 
}

Which Produces the following table(MySQL):

CREATE
    TABLE capacity
    (
        MONTH DATETIME NOT NULL,
        company_id bigint NOT NULL,
        version bigint NOT NULL,
        note VARCHAR(255) NOT NULL,
        PRIMARY KEY (MONTH, company_id),
        INDEX FKFBF514BA69595C7A (company_id)
    )
    ENGINE=MyISAM DEFAULT CHARSET=latin1

Answer 2

It should be something like:

static constraints = {              
    month(blank:false, nullable:false, unique:'company')
    company(blank:false, nullable:false)
}

Take a look at http://grails.org/doc/latest/ref/Constraints/unique.html.

Answer 3

Dave's answer is the right way and the Grails way of doing it.