Multi-database support

[copelco]

Projects using multiple databases cannot use django-pgviews outside of the default database.

I'm using django-pgviews on a project connected to two databases. In our case, the default database is quite small, while the 2nd database is large and could make valuable use of materialized views.

To support multiple databases, I think the following modifications need to be made:

1. Modify how connection cursors are obtained to make use of the connections dictionary:

   https://github.com/mikicz/django-pgviews/blob/269c17f3e08c76a7cb971afcf2241ee76858589c/django_pgviews/view.py#L176

   https://github.com/mikicz/django-pgviews/blob/269c17f3e08c76a7cb971afcf2241ee76858589c/django_pgviews/view.py#L441

2. Update view creation to refer to the database router's allow_migrate so views are only created within the appropriate database.

3. Update management commands to support running against specific databases, as migrate works. For example:

   python manage.py sync_pgviews  # default db
   python manage.py sync_pgviews --database=customers

In the end, the majority of users using a single database shouldn't notice any differences and everything will continue to function as normal 🤞

I have a proof of concept currently working on a fork. Would there be any interest in possibly incorporating these changes if I can put together a PR?

[mikicz]

Hi Colin,

I'd be happy to review, merge and release such a PR, if it's coded well (mainly meaning following the style of the project, adding tests and documentation) and no breaking changes are introduced (everything should remain as is for current users with just the default database).

I think there's also issues about this in the original repo (mypebble/django-pgviews#39, mypebble/django-pgviews#52) and there's also an unfinished PR for this in this repo (#1), so it seems a lot of people could use this!

[mikicz]

Implemented in #10, released as 0.8.0 to PyPI.