SQLAlchemy set default nullable=False

Question

I'm using SQLAlchemy for Flask to create some models. The problem is, nearly all my columns need nullable=False, so I'm looking for a way to set this option as default when creating a column. Surely I could add them manually (as a Vim exercise), but I just don't feel like it today. For a reference, this is how my setup (models.py) looks like:

from flask.ext.sqlalchemy import SQLAlchemy  db = SQLAlchemy()  class User(db.Model):      id = db.Column(db.Integer, primary_key=True)      username = db.Column(db.String(80), nullable=False) 

and many more. Is there a simple way of doing this?

Thanks in advance.

Answer 1

As Column is a class, subclassing seems a lot more extensible to me ¹. Depending on the IDE you are using, code completion may still work.

from sqlalchemy.sql.schema import Column as SAColumn      class Column(SAColumn):     def __init__(self, *args, **kwargs):         kwargs.setdefault('nullable', False)         super().__init__(*args, **kwargs) 

_{db.Column is the Column class by SQLAlchemy. It was just imported by flask-sqlalchemy together with other SQLAlchemy definitions so the library users don't need to import from different places. Only one import is needed then.}

_{¹ One could set attributes directly after instantiation, like self.nullable, for instance.}

Answer 2

just create a wrapper that sets it

def NullColumn(*args,**kwargs):     kwargs["nullable"] = kwargs.get("nullable",True)     return db.Column(*args,**kwargs)  ... username = NullColumn(db.String(80)) 

using functools.partial as recommended in the comments

from functools import partial NullColumn = partial(Column,nullable=True)