An example of building a many-to-many relationship with rom.

many_to_many.py

import rom

class ModelA(rom.Model):
    m2m_test = rom.OneToMany('HiddenModel')

    @property
    def b_models(self):
        return [x.model_b for x in self.m2m_test]

    def add_reference(self, b_object):
        # requires session.commit()
        HiddenModel(model_a=self, model_b=b_object)

    def del_reference(self, b_object):
        pk = b_object._pk
        for x in self.m2m_test:
            if x.model_b._pk == pk:
                x.delete()

class ModelB(rom.Model):
    m2m_test = rom.OneToMany('HiddenModel')

    @property
    def a_models(self):
        return [x.model_a for x in self.m2m_test]

    def add_reference(self, a_object):
        # requires session.commit()
        HiddenModel(model_a=a_object, model_b=self)

    def del_reference(self, a_object):
        pk = a_object._pk
        for x in self.m2m_test:
            if x.model_a._pk == pk:
                x.delete()

class HiddenModel(rom.Model):
    model_a = rom.ManyToOne('ModelA')
    model_b = rom.ManyToOne('ModelB')