Integrating Django with a legacy database

While Django is best suited for developing new applications, it’s quitepossible to integrate it into legacy databases. Django includes a couple ofutilities to automate as much of this process as possible.

This document assumes you know the Django basics, as covered in thetutorial.

Once you’ve got Django set up, you’ll follow this general process to integratewith an existing database.

Give Django your database parameters

You’ll need to tell Django what your database connection parameters are, andwhat the name of the database is. Do that by editing the DATABASESsetting and assigning values to the following keys for the 'default'connection:

• NAME
• ENGINE
• USER
• PASSWORD
• HOST
• PORT

Auto-generate the models

Django comes with a utility called inspectdb that can create modelsby introspecting an existing database. You can view the output by running thiscommand:

$ python manage.py inspectdb

Save this as a file by using standard Unix output redirection:

$ python manage.py inspectdb > models.py

This feature is meant as a shortcut, not as definitive model generation. See thedocumentation of inspectdb for more information.

Once you’ve cleaned up your models, name the file models.py and put it inthe Python package that holds your app. Then add the app to yourINSTALLED_APPS setting.

By default, inspectdb creates unmanaged models. That is,managed = False in the model’s Meta class tells Django not to manageeach table’s creation, modification, and deletion:

class Person(models.Model):
    id = models.IntegerField(primary_key=True)
    first_name = models.CharField(max_length=70)
    class Meta:
       managed = False
       db_table = 'CENSUS_PERSONS'

If you do want to allow Django to manage the table’s lifecycle, you’ll need tochange the managed option above to True(or remove it because True is its default value).

Install the core Django tables

Next, run the migrate command to install any extra needed databaserecords such as admin permissions and content types:

$ python manage.py migrate

Test and tweak

Those are the basic steps – from here you’ll want to tweak the models Djangogenerated until they work the way you’d like. Try accessing your data via theDjango database API, and try editing objects via Django’s admin site, and editthe models file accordingly.