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):
...
