Question

I have a project (#1) with a couple apps in it using a mysql database #1. I also have another project (#2) whose django code is on the same server, but it uses a different mysql database (#2).

My goal is to be running a web app in project #1 and use the django models from project #2 for a simple query against db #2. However, when I import from project #2, it still uses the #1 database, even though the settings.py file for #2 is appropriately using database #2 (i.e. when I run the web app in project #2, it works fine).

Here is the entirety of a file that I can successfully run as a standalone script. Sadly, when I import the file into project #1 and run the function, it fails (because it is looking in db#1 for the table):

import sys

def get_stuff_from_project2(ids):
    from django.core.management import setup_environ
    from project2 import settings
    setup_environ(settings)

    from project2.myapp2.models import mymodel2

    all_rows = mymodel2.objects.filter(id__in=ids).values()
    return(all_rows)

# as a standalone script, run the main function
if __name__ == "__main__":
    sys.path.append("/home/me/django")
    print str ( get_stuff_from_project2( sys.argv[1:] ) )

Again, this works as a standalone script. But, from project #1 (using code below) it fails with a DatabaseError, Table ‘db1.myapp2_mymodel2’ doesn’t exist:

from project1.myapp1.standalone_script import get_stuff_from_project2
all_rows = get_stuff_from_project2( ids )

My guess here is that the setup_environ function does not actually process the new DATABASE_NAME, or that it can’t change an existing DATABASE_NAME once the settings have been set?

I’m a bit lost at this point and have been trying to search for a solution. I don’t really want to go down the “multi-site” or “multi-database” approach, since I would really like to keep project 1 and project 2 as separate as possible. My alternative would be to call the standalone script as a system call from within project 1, or to make a view in project 2 which is an API and sends data out. But, I thought that just using a model would be simplest if it worked.

Thanks.

——- added April 13, 11:35 PST —-

Here’s a simpler version of the question: How can I access two different projects from a single standalone script. The following code works ok for whichever project I do setup_environ on first, but it can’t do the second one:

import sys
from django.core.management import setup_environ
sys.path.append('/home/me/django')

from project1 import settings
print setup_environ(settings)  # shows /home/me/django/project1
print settings.DATABASE_NAME   # shows db1
from project1.myapp1.models import mymodel1
mymodel1.objects.filter(id=9376544).values()  # works fine

from project2 import settings
print setup_environ(settings)  # shows /home/me/django/project2
print settings.DATABASE_NAME   # shows db2
from project2.myapp2.models import mymodel2
mymodel2.objects.filter(id=6544).values() # fails with:
# django.db.utils.DatabaseError: (1146, "Table 'db1.myapp2_mymodel2' doesn't exist")

Answer 1

I was unable to solve this using a single script. I instead used two scripts: the first called the second as a shell command, and the second output formatted data as a list to stdout.

This has been robust enough for the problem of reading a single stream of data from another app’s database, but would not be suitable for a larger problem such as requiring several queries or writing to the second app’s data. For the more complex problem, add APIs (XMLRPC, REST are easy in Django) to make calls into the running apps.