what is correct way to define Many2Many, Many2One in mongoengine

Question

I am creating a data model for my new project where I have to use Many2Many, Many2One, One2Many reference using flask-mongoengine. Can someone describe how to define Many2Many and other reference field using mongoengine?

Answer 1

The following are the most common ways to do it:

1) 1-to-many with a simple ReferenceField

class Client(Document):
    name = StringField()

    @property
    def account(self):
          return Account.objects(client=self).get()  

class Account(Document):
    client = ReferenceField(Client)

bob = Client(name='Bob').save()
acc1 = Account(client=bob).save()
acc2 = Account(client=bob).save()

2) Many-2-Many with a list(ReferenceField)

class Client(Document):
    name = StringField()

    @property
    def accounts(self):
          return Account.objects(client=self)  

class M2MAccount(Document):
    clients = ListField(ReferenceField(Client))

bob = Client(name='Bob').save()
john = Client(name='John').save()
m2m_acc = M2MAccount(clients=[bob, john]).save()

Note that the @property is optional, its just for convenience