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grailsgrails-orm

grails hasOne vs hasMany behavior

In grails, when specifying a unidirectional one-to-one relationship, I can do either

class MyDomainClass {
   AnotherDomainClass another
}

or

class MyDomainClass {
   static hasOne = [another:AnotherDomainClass]
}

I know the semantics are different, but either way will establish this relationship.

When creating a hasMany relationship, I can do:

class MyDomainClass {
  static hasMany = [others:AnotherDomainClass]
}

But I can't seem to do:

class MyDomainClass {
  List<AnotherDomainClass> others 
}

Edit: Clarification. I would like to still have the hasMany relationship, I'm just wondering if it's possible to do so just by declaring List<AnotherDomainClass> others without the hasMany variable. I was hoping that just declaring List<AnotherDomainClass> would create a join table automatically.

Solution

  • Yes, you can do. Just declare both.

    class MyDomainClass {

  List<AnotherDomainClass> others 

  static hasMany = [others:AnotherDomainClass]

}

    When you not declare the field, Grails automatically create a Set for you.