Multiple Database Config In Django 1.2

This is hopefully an easy question. I'm having some trouble understanding the documentation for the new multiple database feature in Django 1.2. Primarily, I cant seem to find an e

Solution 1:

Yeah, it is a little bit complicated.

There are a number of ways you could implement it. Basically, you need some way of indicating which models are associated with which database.

First option

Here's the code that I use; hope it helps.

from django.db import connections

classDBRouter(object):
    """A router to control all database operations on models in
    the contrib.auth application"""defdb_for_read(self, model, **hints):
        m = model.__module__.split('.')
        try:
            d = m[-1]
            if d in connections:
                return d
        except IndexError:
            passreturnNonedefdb_for_write(self, model, **hints):
        m = model.__module__.split('.')
        try:
            d = m[-1]
            if d in connections:
                return d
        except IndexError:
            passreturnNonedefallow_syncdb(self, db, model):
        "Make sure syncdb doesn't run on anything but default"if model._meta.app_label == 'myapp':
            returnFalseelif db == 'default':
            returnTruereturnNone

The way this works is I create a file with the name of the database to use that holds my models. In your case, you'd create a separate models-style file called asterisk.py that was in the same folder as the models for your app.

In your models.py file, you'd add

from asterisk import *

Then when you actually request a record from that model, it works something like this:

1. records = MyModel.object.all()
2. module for MyModel is myapp.asterisk
3. there's a connection called "asterisk" so use it instead of "default"

Second Option

If you want to have per-model control of database choice, something like this would work:

from django.db import connections

classDBRouter(object):
    """A router to control all database operations on models in
    the contrib.auth application"""defdb_for_read(self, model, **hints):
        ifhasattr(model,'connection_name'):
            return model.connection_name
        returnNonedefdb_for_write(self, model, **hints):
        ifhasattr(model,'connection_name'):
            return model.connection_name
        returnNonedefallow_syncdb(self, db, model):
        ifhasattr(model,'connection_name'):
            return model.connection_name
        returnNone

Then for each model:

classMyModel(models.Model):
    connection_name="asterisk"#etc...

Note that I have not tested this second option.

Solution 2:

An addendum to Jordans answer above. For the second option, the allow_syncdb method works correctly as follows:

defallow_syncdb(self, db, model):
    ifhasattr(model,'connection_name'):
        return model.connection_name == db
    return db == 'default'

Solution 3:

Does the documentation on automatic database routing and manually selecting a database not help?