Grails: Prevent cascading association between two domain classes with multiple relationships

Question

Consider two domain classes; Job and Quote.

A Job has many Quotes but a Job also has an accepted quote. The accepted quote is nullable and should only be set once a part

Answer 1

This may not be what you are looking for but I would actually model this a little differently - I would have an accepted flag in the Quote domain:

class Job {
    String title
    static hasMany = [quotes: Quote]
}

class Quote {
    static belongsTo = [job: Job]
    BigDecimal quoteAmount
    Boolean accepted
}

Then your persistence could look like this:

jobInstance.addToQuotes(new Quote(quoteAmount: 123.34, accepted: false)) //or true

and no worries regarding your original problem.

You could also add a transient and its getter to the Job class to get the accepted Quote

class Job {
    String title
    static hasMany = [quotes: Quote]

    static transients = ['acceptedQuote']

    Quote getAcceptedQuote() {
        return Quote.findByJobAndAccepted(this, true)
    }

}