Question

I have two domain classes: Contract and Orgainisation. A contract has one contractor (which is an instance of Orgaisation) and many/one/none beneficiaries (which are instances of Orgaisation also). How do I model these relationships? I want Contract to own both relationships so that I can do something like:

contractInstance = new Contract()
contractInstance.addToBeneficiaries(name: 'A Company')
contractInstance.addToBeneficiaries(name: 'Other Company')
contractInstance.contractor = new Orgaisation('Antoher Company')
contractInstance.save()

I tried a few things but keep getting error messages (transient value, no owning class for a many-to-many relationship and so on…)

contract

static belongsTo = [contractor:Organisation]
static hasMany = [beneficiaries:Organisation]

orgainisation

static hasMany = [contractorContracts:Contract, beneficiariesContracts:Contract]

How do I represent these relationships?

EDIT: I forgot to mention the contract-beneficiary should be a many-to-many association (I want to reuse beneficiaries accross contracts).

Answer 1

My solution is to make explicit the M:M joining class with a descriptive name. In your case it seems like we can make a class ProvidedService or something like that and have:

Contract {
  static belongsTo = [contractor: Organization]
  static hasMany = [benefits: ProvidedService]
}
Organization {
  static hasMany = [contractorContracts: Contract, receivedServices: ProvidedService]
}
ProvidedService {
  //Feasibly there could be differences in the service provided to each beneficiary of a contract which could go in here.
  static belongsTo = [contract: Contract, serviceRecipient: Organization]
}