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pythonsqlalchemypylonspython-elixir

Elixir reflection

I define some Entities which works fine; for meta programming issues. I now need to reflect the field properties defined in the model.

For example:

class Foo(Entity):
      bar = OneToMany('Bar')
      baz = ManyToMany('Baz')

Which type of relation is set: "ManyToMany", "OneToMany" or even a plain "Field", and the relation target?

Is there any simple way to reflect the Elixir Entities?

Solution

  • You can do introspection in Elixir as you would anywhere in Python -- get all names of attributes of class Foo with dir(Foo), extract an attribute given its name with getattr(Foo, thename), check the type of the attribute with type(theattr) or isinstance, etc. The string 'Bar' that you pass as the attribute to the constructor of any Relationship subclass (including OneToMany and ManyToMany) ends up as the r.of_kind attribute of the resulting instance r of the Relationship subclass.

    Module inspect in the Python standard library may be a friendlier way to do introspection, but dir / getattr / isinstance &c are perfectly acceptable in many cases.