Polymorphism

You must get code in III-06-before_polymorphism directory from AnyBlok/anyblok-book-examples repository before starting as we have had some code source to explain this chapter:

git clone https://github.com/AnyBlok/anyblok-book-examples -b III-06-polymorphisme
cd III-06-polymorphisme/III-06-before_polymorphisme

Polymorphism in AnyBlok allows you to share same database table with different models.

It helps building elegant and comprehensive Python API, each polymorphic model can be accessed through a different namespace (Employee vs Employee.Professor for example). Namespacing is also helpful for giving different behaviours per polymorphic models

We have added some models to get started with polymorphism:

• A person blok that contains following models
  • Person model that represents people with a name and firstname
  • Employee model that adds position field on person model using polymorphism
• A university blok that represents all things regarding education
  • Professor model that extends Employee model using polymorphism
  • Student model that extends Person model using polymorphism

As you can see a Professor is an Employee of another kind. Anyblok polymorphism will help for:

Querying all persons through registry.Person namespace

In [1]: registry.Person.query().all()
Out[1]: [<Model.Person(first_name='Alice', id=1, last_name='Wunderer', person_type='person')>,
 <Model.Person.Employee(first_name='John', id=2, last_name='Doe', person_type='employee', position=<not loaded>)>]

Querying all employees through registry.Person.Employee

```python In [2]: registry.Person.Employee.query().all() Out[2]: []

We also add the University model thats links to the Address model, an university could have from zero to N addresses.

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