Grails GORM many-to-many relationship

Question

I want to delete all the Tweet s when its parent User is deleted, also delete the collaborators when its parent Tweet is deleted. Wherein collaborators if of type User

Currently, Tweet view doesn't hook up collaborators. I am thinking if I'm doing the following right:

Tweet.groovy

User owner
static hasMany = [ collaborators : User ]
static belongsTo = User

User.groovy

static hasMany = [ tweet : Tweet ] 

Answer 1

It seems to me that you lack one relationship that states that a tweet is owned by a particular user. As it is now you will only get a many-to-many relation and I guess you don't want to delete all tweets that a user has collaborated in when you delete a user.

Tweet.groovy

static hasMany = [ collaborators : User ]
static belongsTo = User
User createdBy
static mappedBy = [collaborators : 'tweet']

User.groovy

static hasMany = [ tweet : Tweet ]
static mappedBy = [tweet : 'collaborators']

The mappedBy above is needed since you will have two relationships between the classes and Grails needs to know which one to use for the many-to-many.