[Sqlalchemy-tickets] Issue #3569: Make MetaData.drop_all() work with foreign keys (zzzeek/sqlalchemy)

[Roman Z. <iss...@bi...>]

New issue 3569: Make MetaData.drop_all() work with foreign keys
https://bitbucket.org/zzzeek/sqlalchemy/issues/3569/make-metadatadrop_all-work-with-foreign

Roman Zimmermann:

Currently issuing a drop_all() for PostgreSQL databases sometimes leads to a foreign key error like:


```
sqlalchemy.exc.InternalError: (psycopg2.InternalError) cannot drop table users because other objects depend on it
DETAIL:  constraint engaging_networks_tokens_user_id_fkey on table engaging_networks_tokens depends on table users
HINT:  Use DROP ... CASCADE to drop the dependent objects too.
 [SQL: '\nDROP TABLE users']
```

This is a major nuissance since drop_all() is commonly used for testing.

A workaround is documented in [this blogpost](http://www.mbeckler.org/blog/?p=218).