I have an intermediate model which I am using to keep track of which labs
to include since individual labs can be removed.
So when you add a new intermediate model (AgendaModel) it automatically
adds all of the labs.
with
@event.listens_for(Agenda.modules, 'append')
But there is a UNIQUE constraint violation.
I'm using Flask and Flask-SQLAlchemy
and
psql (PostgreSQL) 9.3.4
Traceback (most recent call last):
File "db.py", line 102, in <module>
db.session.commit()
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/scoping.py",
line 149, in do
return getattr(self.registry(), name)(*args, **kwargs)
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py",
line 768, in commit
self.transaction.commit()
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py",
line 370, in commit
self._prepare_impl()
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py",
line 350, in _prepare_impl
self.session.flush()
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py",
line 1907, in flush
self._flush(objects)
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py",
line 2025, in _flush
transaction.rollback(_capture_exception=True)
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/util/langhelpers.py",
line 57, in __exit__
compat.reraise(exc_type, exc_value, exc_tb)
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py",
line 1989, in _flush
flush_context.execute()
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/unitofwork.py",
line 371, in execute
rec.execute(self)
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/unitofwork.py",
line 480, in execute
self.dependency_processor.process_saves(uow, states)
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/dependency.py",
line 1087, in process_saves
secondary_update, secondary_delete)
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/orm/dependency.py",
line 1130, in _run_crud
connection.execute(statement, secondary_insert)
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py",
line 727, in execute
return meth(self, multiparams, params)
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/sql/elements.py",
line 322, in _execute_on_connection
return connection._execute_clauseelement(self, multiparams, params)
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py",
line 824, in _execute_clauseelement
compiled_sql, distilled_params
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py",
line 954, in _execute_context
context)
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py",
line 1116, in _handle_dbapi_exception
exc_info
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/util/compat.py",
line 189, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb)
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py",
line 924, in _execute_context
context)
File
"/home/siecje/Desktop/db/venv/local/lib/python2.7/site-packages/sqlalchemy/engine/default.py",
line 432, in do_executemany
cursor.executemany(statement, parameters)sqlalchemy.exc.IntegrityError:
(IntegrityError) UNIQUE constraint failed: agenda_labs.lab_id,
agenda_labs.agenda_id, agenda_labs.module_id u'INSERT INTO agenda_labs (lab_id,
agenda_id, module_id) VALUES (?, ?, ?)' ((1, 1, 1), (1, 1, 1))
from flask import Flaskfrom flask.ext.sqlalchemy import SQLAlchemy
app = Flask(__name__)app.config['SQLALCHEMY_DATABASE_URI'] =
'sqlite:///test.db'db = SQLAlchemy(app)
from sqlalchemy import funcfrom sqlalchemy.ext.orderinglist import ordering_list
# Many-To-Many tablesmodule_labs = db.Table('module_labs',
db.Column('lab_id', db.Integer, db.ForeignKey('labs.id'), primary_key=True),
db.Column('module_id', db.Integer, db.ForeignKey('modules.id'),
primary_key=True))
agenda_labs = db.Table('agenda_labs',
db.Column('lab_id', db.Integer, db.ForeignKey('labs.id'), primary_key=True),
db.Column('agenda_id', db.Integer, primary_key=True),
db.Column('module_id', db.Integer, primary_key=True),
db.ForeignKeyConstraint(['agenda_id', 'module_id'],
['agenda_modules.agenda_id', 'agenda_modules.module_id']))
class AgendaModule(db.Model):
__tablename__ = 'agenda_modules'
module_id = db.Column(db.Integer, db.ForeignKey('modules.id'),
primary_key=True)
agenda_id = db.Column(db.Integer, db.ForeignKey('agendas.id'),
primary_key=True)
module_position = db.Column(db.Integer)
module = db.relationship('Module', backref='agendas')
# Used to remove individual labs from a module
labs = db.relationship('Lab', secondary=agenda_labs,
backref=db.backref('agendas', lazy='dynamic'))
def __unicode__(self):
return self.module.name
class Lab(db.Model):
__tablename__ = 'labs'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.Text, nullable=False)
def __repr__(self):
return '<Lab %r>' % self.name
class Module(db.Model):
__tablename__ = 'modules'
id = db.Column(db.Integer, primary_key=True)
location = db.Column(db.Text, unique=True)
name = db.Column(db.Text, nullable=False)
labs = db.relationship('Lab', secondary=module_labs,
backref=db.backref('modules', lazy='dynamic'))
def __repr__(self):
return '<Module %r>' % self.name
class Agenda(db.Model):
__tablename__ = 'agendas'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.Text)
modules = db.relationship('AgendaModule', backref='agenda',
order_by=AgendaModule.module_position,
collection_class=ordering_list('module_position'))
def __repr__(self):
return '<Agenda %r>' % self.name
# Automatically deal with adding modules to Agendas and Bundlesfrom sqlalchemy
import event
@event.listens_for(Agenda.modules, 'append')def include_all(agenda,
agenda_module, initiator):
""" Include all Labs, Lectures, Videos when a module is added. """
for lab in agenda_module.module.labs or []:
agenda_module.labs.append(lab)
return agenda_module
if __name__ == '__main__':
db.create_all()
# Create agenda with modules with labs, lectures, videos
agenda = Agenda(name='Agenda to be Deleted')
module = Module(name='Module for Labs')
lab1 = Lab(name='Lab')
module.labs.append(lab1)
am = AgendaModule()
am.module = module
am.agenda = agenda
agenda.modules.append(am)
db.session.add(agenda)
db.session.commit()
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