One sided relations and more powerful save_related

0.10.3

✨ Features

• ForeignKey and ManyToMany now support skip_reverse: bool = False flag #118.
  If you set skip_reverse flag internally the field is still registered on the other
  side of the relationship so you can:

  • filter by related models fields from reverse model
  • order_by by related models fields from reverse model

  But you cannot:

  • access the related field from reverse model with related_name
  • even if you select_related from reverse side of the model the returned models won't be populated in reversed instance (the join is not prevented so you still can filter and order_by)
  • the relation won't be populated in dict() and json()
  • you cannot pass the nested related objects when populating from dict() or json() (also through fastapi). It will be either ignored or raise error depending on extra setting in pydantic Config.

• Model.save_related() now can save whole data tree in once #148
  meaning:

  • it knows if it should save main Model or related Model first to preserve the relation

  • it saves main Model if

    • it's not saved,
    • has no pk value
    • or save_all=True flag is set

    in those cases you don't have to split save into two calls (save() and save_related())

  • it supports also ManyToMany relations

  • it supports also optional Through model values for m2m relations

• Add possibility to customize Through model relation field names.

• By default Through model relation names default to related model name in lowercase.
  So in example like this:

  ... # course declaration ommited
  class Student(ormar.Model):
      class Meta:
          database = database
          metadata = metadata
  
      id: int = ormar.Integer(primary_key=True)
      name: str = ormar.String(max_length=100)
      courses = ormar.ManyToMany(Course)
  
  # will produce default Through model like follows (example simplified)
  class StudentCourse(ormar.Model):
      class Meta:
          database = database
          metadata = metadata
          tablename = "students_courses"
  
      id: int = ormar.Integer(primary_key=True)
      student = ormar.ForeignKey(Student) # default name
      course = ormar.ForeignKey(Course)  # default name

• To customize the names of fields/relation in Through model now you can use new parameters to ManyToMany:

  • through_relation_name - name of the field leading to the model in which ManyToMany is declared
  • through_reverse_relation_name - name of the field leading to the model to which ManyToMany leads to

  Example:

  ... # course declaration ommited
  class Student(ormar.Model):
      class Meta:
          database = database
          metadata = metadata
  
      id: int = ormar.Integer(primary_key=True)
      name: str = ormar.String(max_length=100)
      courses = ormar.ManyToMany(Course,
                                 through_relation_name="student_id",
                                 through_reverse_relation_name="course_id")
  
  # will produce default Through model like follows (example simplified)
  class StudentCourse(ormar.Model):
      class Meta:
          database = database
          metadata = metadata
          tablename = "students_courses"
  
      id: int = ormar.Integer(primary_key=True)
      student_id = ormar.ForeignKey(Student) # set by through_relation_name
      course_id = ormar.ForeignKey(Course)  # set by through_reverse_relation_name