Flask-SQLAlchemy serializable objects with integer, float and boolean types in JSON

Question

I am using Flask 1.1.2 and Flask-SQLAlchemy 2.4.4 to create a RESTFul service.

I want all of my model classes to be serializable and so have written a base class that my models derive from. In my Serializable class, the method as_dict() returns the string value of a column. However, I want to be modify the method to:

Return integers and floats (not their string version)
Boolean types to be returned in valid JSON (i.e. true, false)

This is my code so far:

class Serializable():
    def as_dict(self):
        return {c.name: str(getattr(self, c.name)) for c in self.__table__.columns}
    
 
class DataFrequency(db.Model, Serializable):
    __tablename__ = 'data_frequency'
    __table_args__ = (
        db.CheckConstraint('period > 0'),
    )

    id = db.Column(db.Integer, primary_key=True, server_default=text("nextval('data_frequency_id_seq'::regclass)"))
    period = db.Column(db.Integer, nullable=False)
    name = db.Column(db.Text, nullable=False, unique=True)

How may I modify the as_dict() method to correctly handle Integer (and it's variants), Floats (and it's variants) and Boolean column types?

Tohmaxxx Tohmaxxx · Accepted Answer · 2020-09-14T10:20:28

you can use column.type.python_type to cast the column value, for ex. c.type.python_type("1") will return 1, instead of "1" if type is int

Flask-SQLAlchemy serializable objects with integer, float and boolean types in JSON

1 Answers