Creating a schemas to validate, serialize, and deserialize users

Now, we will create the Flask-Marshmallow schema that we will use to validate, serialize and deserialize the previously declared User model. Open the api/models.py file and add the following code after the existing lines. The code file for the sample is included in the restful_python_chapter_07_02 folder:

class UserSchema(ma.Schema): 
    id = fields.Integer(dump_only=True) 
    name = fields.String(required=True, validate=validate.Length(3)) 
    url = ma.URLFor('api.userresource', id='<id>', _external=True) 

The code declares the UserSchema schema, specifically a subclass of the ma.Schema class. Remember that the previous code we wrote for the api/models.py file created a flask_marshmallow.Mashmallow instance named ma.

We declare the attributes that represent fields as instances of the appropriate class declared in the marshmallow.fields module. The UserSchema class declares the name attribute as an instance of fields...