How to integrate GingerDJ with a legacy database

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

This document assumes you know the GingerDJ basics, as covered in the tutorial.

Once you’ve got GingerDJ set up, you’ll follow this general process to integrate with an existing database.

Give GingerDJ your database parameters

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

• NAME

• ENGINE

• USER

• PASSWORD

• HOST

• PORT

Auto-generate the models

GingerDJ comes with a utility called inspectdb that can create models by introspecting an existing database. You can view the output by running this command:

$ 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 the documentation of inspectdb for more information.

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

By default, inspectdb creates unmanaged models. That is, managed = False in the model’s Meta class tells GingerDJ not to manage each 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 GingerDJ to manage the table’s lifecycle, you’ll need to change the managed option above to True (or remove it because True is its default value).

Install the core GingerDJ tables

Next, run the migrate command to install any extra needed database records 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 GingerDJ generated until they work the way you’d like. Try accessing your data via the GingerDJ database API, and try editing objects via GingerDJ’s admin site, and edit the models file accordingly.