Creating models with their relationships

Now, we will create the models that we will use to represent and persist the notification categories, notifications, and their relationships in the PostgreSQL database.

Open the service/models.py file and replace its contents with the following code. The lines that declare fields related to other models are highlighted in the code listing. If you created a new virtual environment, create a new models.py file within the service folder. The code file for the sample is included in the restful_python_2_02_01 folder, in the Flask01/service/models.py file:

from marshmallow import Schema, fields, pre_load 
from marshmallow import validate 
from flask_sqlalchemy import SQLAlchemy 
from flask_marshmallow import Marshmallow 
 
 
orm = SQLAlchemy() 
ma = Marshmallow() 
 
 
class ResourceAddUpdateDelete():    
    def add(self, resource): 
       ...