Three domain classes relationship in GORM - grails

Question

is there a special way with gorm to map a three domain classes relationship like this:
1 person belongs to N companies with M given roles (one or more roles for a given company)
Thanks in advance.

Answer 1

look at http://www.grails.org/Many-to-Many+Mapping+without+Hibernate+XML (i think it's up to date).
be aware of: http://codedumpblog.blogspot.com/2010/02/grails-many-to-many-with-lists.html
the code below works for me using grails 1.2.0. but it seems like i had to do a lot of save()'s. don't forget to make the controllers and set scaffold=domain_class
package p
class Company {
String toString() { "$name"
}
static hasMany=[roles:Role]
static constraints = {
}
String name
}
package p
class Role {
String toString() { "$name"
}
static belongsTo=[company:Company]
static hasMany=[personRoleAssociations:PersonRoleAssociation]
static constraints = {
}
String name
}
package p
class Person {
String toString() { "$name"
}
static hasMany=[personRoleAssociations:PersonRoleAssociation]
static constraints = {
}
String name
}
package p
class PersonRoleAssociation {
String toString() { "${person.name} as ${role.name}"
}
static belongsTo=[person:Person,role:Role]
static constraints = {
}
}
import p.*
class BootStrap {
def init = { servletContext ->
Person dick=new Person(name:'dick')
Person jane=new Person(name:'jane')
dick.save()
jane.save()
Company ibm=new Company(name:'ibm')
ibm.save()
Role ibmManager=new Role(name:'ibmmanager')
Role ibmPeon=new Role(name:'ibmpeon')
ibm.addToRoles(ibmManager)
ibmManager.save()
ibm.addToRoles(ibmPeon)
ibmPeon.save()
ibm.save()
Company sun=new Company(name:'sun')
sun.save()
Role sunManager=new Role(name:'sunmanager')
Role sunPeon=new Role(name:'sunpeon')
sun.addToRoles(sunManager)
sunManager.save()
sun.addToRoles(sunPeon)
sunPeon.save()
sun.save()
PersonRoleAssociation dickManager=new PersonRoleAssociation()
dick.addToPersonRoleAssociations(dickManager)
ibmManager.addToPersonRoleAssociations(dickManager)
PersonRoleAssociation dickPeon=new PersonRoleAssociation()
dick.addToPersonRoleAssociations(dickPeon)
sunPeon.addToPersonRoleAssociations(dickPeon)
PersonRoleAssociation janeManager=new PersonRoleAssociation()
jane.addToPersonRoleAssociations(janeManager)
sunManager.addToPersonRoleAssociations(janeManager)
PersonRoleAssociation janePeon=new PersonRoleAssociation()
jane.addToPersonRoleAssociations(janePeon)
ibmPeon.addToPersonRoleAssociations(janePeon)
}
def destroy = {
}
}

Answer 2

I would try :
class Person {
String name
Set<Role> roles
Set<Company> companies
public String toString() {
return name + " roles : " + (roles.collect { it.name }).toString() + " - companies : " + (companies.collect { it.name }).toString()
}
static hasMany = [companies:Company, roles:Role]
static constraints = {
name (unique:true)
roles (nullable:true)
}
}
class Role {
String name
String toString() {
return name + " companies : " + (companies.collect { it.name }).toString()
}
static hasMany = [companies : Company]
static belongsTo = Company
static constraints = {
name (unique:true)
companies (nullable:false)
}
}
class Company {
String name
String toString() {
return name + " roles : " + (roles.collect { it.name }).toString()
}
static hasMany = [roles : Role]
static constraints = {
name (unique:true)
roles (nullable:true)
}
}
Didn't test though... I'd be interested in knowing if my solution has any problems and what they can be...