[Sqlalchemy-tickets] Issue #3976: Built-in way to convert an ORM object (i.e. result of an ORM query) to a Python dictionary (zzzeek/sqlalchemy)

[Markus M. <iss...@bi...>]

New issue 3976: Built-in way to convert an ORM object (i.e. result of an ORM query) to a Python dictionary
https://bitbucket.org/zzzeek/sqlalchemy/issues/3976/built-in-way-to-convert-an-orm-object-ie

Markus Meskanen:

I suggest adding something that allows us to convert ORM objects directly into dictionaries like this:
```
#!python
class User(Base):
    __tablename__ = 'user'
    id = Column(Integer, primary_key=True)
    name = Column(Text, required=True)
    birth_year = Column(Integer)

user = session.query(User).filter(User.birth_year==1996).one()
return dict(user)
```
This would not only allow extremely easy integration with JSON APIs, but sometimes it's better to handle these objects as dicts for speed etc.

Some things to consider:

- Recursion; what to do with relationships? Should one-to-many convert to a dict of lists? What if all of those many have more "sub" lists?
- Method of converting:
  1. Support `dict(obj)`, integrates neatly into Python and this way it supports more than just `dict()`, like custom mapping classes
  2. Add a `to_dict()` method to the declarative base class. I like this the *least*, because an object shouldn't know how to convert itself into everything in the world
  3. A custom function like `sqlalchemy.orm.to_dict(obj)`. Imo better than #2, and it doesn't clutter the class either.
- Ignore fields, i.e. "convert this object to a dict, but ignore `id` column"