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4adebd3 Mar 1, 2018
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# -*- coding: utf-8 -*-
"""Database module, including the SQLAlchemy database object and DB-related utilities."""
from .compat import basestring
from .extensions import db
# Alias common SQLAlchemy names
Column = db.Column
relationship = db.relationship
class CRUDMixin(object):
"""Mixin that adds convenience methods for CRUD (create, read, update, delete) operations."""
def create(cls, **kwargs):
"""Create a new record and save it the database."""
instance = cls(**kwargs)
def update(self, commit=True, **kwargs):
"""Update specific fields of a record."""
for attr, value in kwargs.items():
setattr(self, attr, value)
return commit and or self
def save(self, commit=True):
"""Save the record."""
if commit:
return self
def delete(self, commit=True):
"""Remove the record from the database."""
return commit and db.session.commit()
class Model(CRUDMixin, db.Model):
"""Base model class that includes CRUD convenience methods."""
__abstract__ = True
# From Mike Bayer's "Building the app" talk
class SurrogatePK(object):
"""A mixin that adds a surrogate integer 'primary key' column named ``id`` to any declarative-mapped class."""
__table_args__ = {'extend_existing': True}
id = Column(db.Integer, primary_key=True)
def get_by_id(cls, record_id):
"""Get record by ID."""
if any(
(isinstance(record_id, basestring) and record_id.isdigit(),
isinstance(record_id, (int, float))),
return cls.query.get(int(record_id))
return None
def reference_col(tablename, nullable=False, pk_name='id', **kwargs):
"""Column that adds primary key foreign key reference.
Usage: ::
category_id = reference_col('category')
category = relationship('Category', backref='categories')
return Column(
db.ForeignKey('{0}.{1}'.format(tablename, pk_name)),
nullable=nullable, **kwargs)