CODEWITHSUNDEEP
grailsgrails-domain-class
batman
batman

Reputation: 3685

Cross Domain class constraints

I'm new to Grails and I have two domain classes like this:

class User {    
    String username
    String password

    static hasMany = ['boards':Board]
    static belongsTo = ['belongsToBoard':Board]
}

class Board {
    String message
    boolean starred
}

Now I want the constraints like "User can have a board with message being unique"(Note that I don't want Board to be unique, but for each User, the message should be unique. Example:

User : batman
Board: test,test (messages)

is not valid, where as:

User: batman
Board: test

User: batgirl
Board: test

is valid one.

Is it possible to do so in the grails constraints block? If not how should I do this?

Thanks in advance.

Upvotes: 0

Views: 97

Answers (1)

Burt Beckwith
Burt Beckwith

Reputation: 75671

Your belongsTo property is unusual - if this is a one-many, i.e. a User has many Boards, then the belongsTo goes on the Board side. This enables cascaded deletes and also only uses two tables; if the relationship isn't bidirectional you get a third to manage the relationship. If it's a many-to-many then you're missing the hasMany in Board.

If it is a one-many and you put this in Board

static belongsTo = [user: User]

then you can put a 2-column unique constraint in Board:

static constraints = {
   message unique: 'user'
}

This is described in the docs on the right in the "Constraints" section under "unique".

Upvotes: 1

Related Questions