remove static resource import for db backends

[Rochi]

The dbhelper uses static import for db backends. That produces in Trac 1.2.3 an error if not all db backends are installed.

We use mysql, so the postgresql python bindings were not installed.

We fixed it with:

import trac.db.pool
import trac.db.sqlite_backend
from pkg_resources import DistributionNotFound
try:
    import trac.db.postgres_backend
except DistributionNotFound:
    pass
import trac.db.mysql_backend

This workaround needs still some optimization.

[Russ Tyndall]

Howdy, I will look into this. I think I am mostly doing this to enable different syntax for specific databases, so I might be able to be more forgiving.

[Russ Tyndall]

In 17249:

Change db backend import stuff to allow running without all backends installed re #13462

[Russ Tyndall]

I think you problem should be resolved in version 1.6.0

[anonymous]

Other plugins use this:

dburi = env.config.get('trac', 'database')
if dburi.startswith('sqlite:'):
    pass
elif dburi.startswith('postgres:'):
    pass
elif dburi.startswith('mysql:'):
    pass

For example https://trac-hacks.org/browser/tracmigrateplugin/0.12/tracmigrate/admin.py

[Rochi]

Replying to anonymous:

Other plugins use this:

dburi = env.config.get('trac', 'database')
if dburi.startswith('sqlite:'):
    pass
elif dburi.startswith('postgres:'):
    pass
elif dburi.startswith('mysql:'):
    pass

For example https://trac-hacks.org/browser/tracmigrateplugin/0.12/tracmigrate/admin.py

I think this is a good approach, but the env is actual not available.

@Russ Thx for the very fast fix.