If you have changed your database schema, you can up date your model by first running the inspectdb command.
python manage.py inspectdb > models.py
If you have too many tables in your database, pipe the results to a temporary file first and then manually copy the models over.
python manage.py inspectdb > models_temp.py
Then run:
python manage.py makemigrations
ref: https://dev.to/idrisrampurawala/creating-django-models-of-an-existing-db-288m