Django: How do I perform database introspection with multiple databases?

Question

I have code that works for getting models and fields from a Django database. However, it only works on the default database.

This function wants a database name, and I'd like to get the tables and fields for that database.

def browse_datasource(request, dbname):
    table_info = []
    # This is what I'd /like/ to be able to do, but it doesn't work:
    # tables = connections[dbname].introspection.table_names()
    tables = connection.introspection.table_names()
    found_models = connection.introspection.installed_models(tables)
    for model in found_models:
        tablemeta = model._meta
        columns = [field.column for field in model._meta.fields]
        table_info.append([model.__name__, columns])

How can I perform introspection on the non-default databases? Is there a correct way to get connection.introspection for a database with the name "example", for example?

Not so related, but have you considered `python manage.py inspectdb > models.py`? — Shang Wang, Feb 09 '16 at 18:37
Yes, that's how I created some of the models in the first place. This is meant to allow users to browse the different database definitions (which may come with different permissions, etc). — Jason Champion, Feb 09 '16 at 19:23
I should also clarify, since it might matter: I'm working in 1.8.x. — Jason Champion, Feb 09 '16 at 19:51
May I ask what's the purpose for doing the introspection like this? If you have everything as model code, isn't that easier for you to handle fields and tables? — Shang Wang, Feb 09 '16 at 19:54
Databases are being added and removed dynamically as part of this app. — Jason Champion, Feb 09 '16 at 20:47

score 4 · Accepted Answer · answered Feb 11 '16 at 21:32

I found the solution. The trick is getting the database connection from the connections list, then getting a cursor and passing that to introspection.table_names, like so:

table_info = []
conn = connections[dbname]
cursor = conn.cursor()
tables = conn.introspection.table_names(cursor)
found_models = conn.introspection.installed_models(tables)
for model in found_models:
    tablemeta = model._meta

Django: How do I perform database introspection with multiple databases?

1 Answers1