Question

i have the following (simplified) domain classes

class Filter {
    String name
    static hasMany = [answers:Answer]
    static belongsTo = [user:User]
}

class User {
    String name
    static hasMany = [answers:Answer, filters:Filter]
}

class Answer {
    String text
}

Then i add answers to the user which is working perfectly. The problem occurs when i delete 1 answer of a user:

def delete = {
    def answer = Answer.get(params.id)
    def users = User.withCriteria() {
        answers{
            eq("id", answer.id)
        }
    }

    for (user in users)
        user.removeFromAnswers(answer)

    answer.delete(flush:true)
    redirect(action:"index")
}

What happens here is that ALL user –> answer associations get deleted.

I only want to delete this 1 answer and of cause all associations the answer is used.

I know this has to do with the missing belongsTo, but i can’t use it because a ansswer can either belong to a user or to an filter…

Answer 1

You can add the belongsTo to set them to nullable:

class Answer {
    String text

    static belongsTo = [user:User, filter:Filter]
    static constraints = {
        user nullable:true
        filter nullable:true
    }
}

and then just delete the Answer directly in the Controller:

def delete = {
    def answer = Answer.get(params.id)
    answer.delete(flush:true)
}

GORM will take care of the rest the cascading for you.