Why use "db.*" in SqlAlchemy?

Question

I am working on a project using Flask and SqlAlchemy. Me and my colleagues found two ways to define a table. Both work, but what is the different?

Possibility I

base = declarative_base()

class Story(base):
        __tablename__ = 'stories'
        user_id = Column(Integer, primary_key=True) 
        email = Column(String(100), unique=True)
        password = Column(String(100), unique=True)

Possibility II

db = SQLAlchemy()

class Story(db.Model):
        __tablename__ = 'stories'
        user_id = db.Column(Integer, primary_key=True) 
        email = db.Column(String(100), unique=True)
        password = db.Column(String(100), unique=True)

We want to choose one option, but which one? It is obvious that both classes inherit from a different parent class, but for what are these two possibilities used for?

use default base and using custom base and DRY each time

sahasrara62
– sahasrara62

2023-01-23 10:27:19 +00:00
Commented Jan 23, 2023 at 10:27 — sahasrara62
– sahasrara62, Commented Jan 23, 2023 at 10:27

ljmc · Accepted Answer · 2023-01-23 18:40:40Z

2

Possibility 1 is raw SQLAlchemy declarative mapping.

Possibility 2 is Flask-SQLAlchemy.

Both map a class to SQL table (or something more exotic in SQL) in a declarative style, i.e. the class is mapped to an automatically generated table.

Choosing which one to use however is a matter of opinion.

I'll say that using Flask-SQLAlchemy is obviously locking the application to Flask, but that's basically a non-problem since switching frameworks is very uncommon.

NB. __tablename__ is optional with Flask-SQLAlchemy.

answered Jan 23, 2023 at 18:40

ljmc

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1 Comment

danangjoyoo Over a year ago

I agree with this answer. For addition, in agile architecture no. 1 is better. In terms of agility, dependency, flexibility and performance (flask-sqlalchemy somehow make it worst). But if you're a beginner, flask-sqlalchemy provide you some features to easily manage your queries.

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