I'm building a flask app and I want to use sqlalchemy observers to update a shipment status once all products inside that shipment become available.
Here's my datamodel:
from app import db
from sqlalchemy_utils import observes
class Shipment(db.Model):
__tablename__ = 'shipment'
id = db.Column(db.Integer, primary_key=True)
products = db.relationship('Product', backref='shipment', lazy='dynamic')
all_products_ready = db.Column(db.Boolean)
#observes('products')
def product_observer(self, products):
for p in self.products:
if p.status != 'ready':
self.all_products_ready = False
return False
self.all_products_ready = True
return True
class Product(db.Model):
__tablename__ = 'product'
id = db.Column(db.Integer, primary_key=True)
shipment_id = db.Column(db.Integer, db.ForeignKey('shipment.id'))
status = db.Column(db.String(120), index=True)
And here is some code I run to test it:
shipment = models.Shipment(products=[models.Product(status='ready'), models.Product(status='not_ready')])
db.session.add(shipment)
db.session.commit()
print(shipment.all_products_ready)
When I run this code I get an InvalidRequestError: Session is already flushing.
Here is the stack trace:
Traceback (most recent call last):
File "test.py", line 5, in <module>
db.session.commit()
File "U:\dev\observertest\flask\lib\site-packages\sqlalchemy\orm\scoping.py",
line 150, in do
return getattr(self.registry(), name)(*args, **kwargs)
File "U:\dev\observertest\flask\lib\site-packages\sqlalchemy\orm\session.py",
line 788, in commit
self.transaction.commit()
File "U:\dev\observertest\flask\lib\site-packages\sqlalchemy\orm\session.py",
line 384, in commit
self._prepare_impl()
File "U:\dev\observertest\flask\lib\site-packages\sqlalchemy\orm\session.py",
line 364, in _prepare_impl
self.session.flush()
File "U:\dev\observertest\flask\lib\site-packages\sqlalchemy\orm\session.py",
line 1985, in flush
self._flush(objects)
File "U:\dev\observertest\flask\lib\site-packages\sqlalchemy\orm\session.py",
line 2012, in _flush
self.dispatch.before_flush(self, flush_context, objects)
File "U:\dev\observertest\flask\lib\site-packages\sqlalchemy\event\attr.py", l
ine 221, in __call__
fn(*args, **kw)
File "U:\dev\observertest\flask\lib\site-packages\sqlalchemy_utils\observer.py
", line 272, in invoke_callbacks
for (root_obj, func, objects) in args:
File "U:\dev\observertest\flask\lib\site-packages\sqlalchemy_utils\observer.py
", line 252, in gather_callback_args
lambda obj: obj not in session.deleted
File "U:\dev\observertest\flask\lib\site-packages\sqlalchemy_utils\functions\o
rm.py", line 741, in getdotattr
last = [v for v in last if condition(v)]
File "U:\dev\observertest\flask\lib\site-packages\sqlalchemy\orm\dynamic.py",
line 245, in __iter__
sess = self.session
File "U:\dev\observertest\flask\lib\site-packages\sqlalchemy\orm\dynamic.py",
line 237, in session
sess.flush()
File "U:\dev\observertest\flask\lib\site-packages\sqlalchemy\orm\session.py",
line 1979, in flush
raise sa_exc.InvalidRequestError("Session is already flushing")
sqlalchemy.exc.InvalidRequestError: Session is already flushing
How can I use my models without getting this error?
I'm not completely sure why, but I think loading the relations using dynamic is causing problems here. In this line:
products = db.relationship('Product', backref='shipment', lazy='dynamic')
you need to change the lazy parameter to select instead of dynamic (or you can take out the lazy parameter alltogether as select is its default).
See the sqlalchemy reference for all the available options.
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I am using a command line argument of -clear to empty the database of my application before the program starts up. My problem is that calling db.drop_all() from the run.py file throws a "no such table" error. I am wondering what the best approach to clearing my database before running the application would be. Here is my relevant code.
run.py
# Imports
from wms import desktopApp, db
from wms.functions import load_data
import argparse
# Parsing command line arguments
description = """IMPORTANT: When loading information to the database, please insure that all files are stored in the
resources folder and that the file format matches that described in the application documentation."""
parser = argparse.ArgumentParser(description=description)
# Arguments
parser.add_argument("-warehouses",
help="Loads the supplied warehouses.csv file into the database when the program is run.",
action="store_true")
parser.add_argument("-itemTemplates",
help="Loads the supplied item_templates.csv file into the database when the program is run.",
action="store_true")
parser.add_argument("-items",
help="Loads the supplied items.csv file into the database when the program is run.",
action="store_true")
parser.add_argument("-clear",
help="Clears the existing database.",
action="store_true")
args = parser.parse_args()
successful = load_data(args.warehouses, args.itemTemplates, args.items)
if not successful:
quit()
if __name__ == '__main__':
# Clear database
if args.clear:
while True:
confirmation = input("Are you sure you want to clear the database? (y/n): ")
if confirmation.lower() in ["yes", "y"]:
# Drop db logic
db.drop_all()
print("Database cleared.")
break
elif confirmation.lower() in ["no", "n"]:
print("Good thing we double checked.")
break
else:
pass
desktopApp.run()
desktopApp.keep_server_running()
init.py
# Imports
from flask import Flask
from flaskwebgui import FlaskUI
from flask_sqlalchemy import SQLAlchemy
# App config
app = Flask(__name__)
app.config["DEBUG"] = True
app.config["TESTING"] = True
app.config["TEMPLATES_AUTO_RELOAD"] = True
app.config["SECRET_KEY"] = '8e3416a9c67b328517b7b758875aaea0'
app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///data.db"
app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False # Removes warning message in console
# Database config
db = SQLAlchemy(app)
from wms.models import Warehouse, Item, ItemTemplate
db.create_all()
# Desktop UI config
desktopApp = FlaskUI(app,
width=1200,
height=675,
browser_path='C:\Program Files (x86)\Google\Chrome\Application\chrome.exe')
models.py
# Imports
from wms import db
from sqlalchemy.ext.hybrid import hybrid_property
# Constants
MAXIMUM_NAME_LEN = 14
LARGE_SCALE_SIZE = 150
# Template for creating items
class ItemTemplate(db.Model):
"""This template will simply store the information related to an item type.
Individual items that will be associated with the warehouse they're stored in
will inherit this information from the item templates."""
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(MAXIMUM_NAME_LEN), unique=True, nullable=False)
price = db.Column(db.Float, nullable=False)
cost = db.Column(db.Float, nullable=False)
size = db.Column(db.Integer, nullable=False)
low_threshold = db.Column(db.Integer, nullable=False)
instances = db.relationship('Item', backref='item_template', lazy=True) # Instances using this item template
#hybrid_property
def total_stock(self):
total_stock = 0
for instance in self.instances:
total_stock += instance.quantity
return total_stock
#hybrid_property
def possible_revenue(self):
return self.total_stock * (self.price - self.cost)
#hybrid_property
def warehouses(self):
return [instance.warehouse for instance in self.instances]
#hybrid_property
def stock(self):
stock = 0
for instance in self.instances:
stock += instance.quantity
return stock
# Actual items
class Item(db.Model):
"""This template will be used to represent the actual items that are associated with a warehouse."""
id = db.Column(db.Integer, primary_key=True)
quantity = db.Column(db.Integer, nullable=False)
warehouse = db.Column(db.String(MAXIMUM_NAME_LEN), db.ForeignKey('warehouse.name'), nullable=False)
item_template_id = db.Column(db.Integer, db.ForeignKey('item_template.id'), nullable=False)
# Warehouse
class Warehouse(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(MAXIMUM_NAME_LEN), unique=True, nullable=False)
capacity = db.Column(db.Integer, nullable=False)
items = db.relationship("Item", backref="home_warehouse", lazy=True)
#hybrid_property
def remaining_capacity(self):
capacityUsed = 0
for item in self.items:
capacityUsed += item.quantity * ItemTemplate.query.filter_by(id=item.item_template_id).first().size
return self.capacity - capacityUsed
#hybrid_property
def possible_revenue(self):
revenue = 0
for item in self.items:
item_temp = ItemTemplate.query.filter_by(id=item.item_template_id).first()
revenue += item.quantity * (item_temp.price - item_temp.cost)
return revenue
#hybrid_property
def total_production_cost(self):
total_production_cost = 0
for item in self.items:
total_production_cost += item.quantity * ItemTemplate.query.filter_by(id=item.item_template_id).first().cost
return total_production_cost
#hybrid_property
def low_stock_items(self):
low_stock = []
for item in self.items:
if item.quantity <= ItemTemplate.query.filter_by(id=item.item_template_id).first().low_threshold:
low_stock.append(item)
return low_stock
#hybrid_property
def large_scale_items(self):
large = []
for item in self.items:
if ItemTemplate.query.filter_by(id=item.item_template_id).first().size >= LARGE_SCALE_SIZE:
large.append(item)
return large
#hybrid_property
def item_names(self):
return [ItemTemplate.query.filter_by(id=item.item_template_id).first().name for item in self.items]
Error message:
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\engine\base.py", line 1799, in _execute_context
self.dialect.do_execute(
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\engine\default.py", line 717, in do_execute
cursor.execute(statement, parameters)
sqlite3.OperationalError: no such table: warehouse
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\waitress\channel.py", line 397, in service
task.service()
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\waitress\task.py", line 168, in service
self.execute()
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\waitress\task.py", line 434, in execute
app_iter = self.channel.server.application(environ, start_response)
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 2091, in __call__
return self.wsgi_app(environ, start_response)
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 2076, in wsgi_app
response = self.handle_exception(e)
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 2073, in wsgi_app
response = self.full_dispatch_request()
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 1518, in full_dispatch_request
rv = self.handle_user_exception(e)
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 1516, in full_dispatch_request
rv = self.dispatch_request()
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\flask\app.py", line 1502, in dispatch_request
return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args)
File "C:\coding\python\projects\WMS\wms\routes.py", line 22, in home
warehouseList = Warehouse.query.all()
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\orm\query.py", line 2711, in all
return self._iter().all()
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\orm\query.py", line 2846, in _iter
result = self.session.execute(
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\orm\session.py", line 1689, in execute
result = conn._execute_20(statement, params or {}, execution_options)
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\engine\base.py", line 1611, in _execute_20
return meth(self, args_10style, kwargs_10style, execution_options)
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\sql\elements.py", line 325, in _execute_on_connection
return connection._execute_clauseelement(
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\engine\base.py", line 1478, in _execute_clauseelement
ret = self._execute_context(
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\engine\base.py", line 1842, in _execute_context
self._handle_dbapi_exception(
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\engine\base.py", line 2023, in _handle_dbapi_exception
util.raise_(
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\util\compat.py", line 207, in raise_
raise exception
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\engine\base.py", line 1799, in _execute_context
self.dialect.do_execute(
File "C:\Users\golin\AppData\Local\Programs\Python\Python310\lib\site-packages\sqlalchemy\engine\default.py", line 717, in do_execute
cursor.execute(statement, parameters)
sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) no such table: warehouse
[SQL: SELECT warehouse.id AS warehouse_id, warehouse.name AS warehouse_name, warehouse.capacity AS warehouse_capacity
FROM warehouse]
(Background on this error at: https://sqlalche.me/e/14/e3q8)
I'm following a Pyramid tutorial: http://pyramid-blogr.readthedocs.io/en/latest/project_structure.html and using Windows 8.
Current result: When I open my localhost address (in firefox), I get the following error:
sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) no such table: entries [SQL: 'SELECT entries.id AS entries_id, entries.title AS entries_title, entries.body AS entries_body, entries.created AS entries_created, entries.edited AS entries_edited \nFROM entries ORDER BY entries.created DESC\n LIMIT ? OFFSET ?'] [parameters: (5, 0)]
Traceback (most recent call last):
File "C:\Python34\Lib\site-packages\pyramid_debugtoolbar\panels\performance.py", line 71, in noresource_timer_handler
result = handler(request)
File "C:\Python34\Lib\site-packages\pyramid\tweens.py", line 62, in excview_tween
reraise(*attrs['exc_info'])
File "C:\Python34\Lib\site-packages\pyramid\compat.py", line 148, in reraise
raise value
File "C:\Python34\Lib\site-packages\pyramid\tweens.py", line 22, in excview_tween
response = handler(request)
File "C:\Python34\Lib\site-packages\pyramid_tm\__init__.py", line 119, in tm_tween
reraise(*exc_info)
File "C:\Python34\Lib\site-packages\pyramid_tm\compat.py", line 15, in reraise
raise value
File "C:\Python34\Lib\site-packages\pyramid_tm\__init__.py", line 98, in tm_tween
response = handler(request)
File "C:\Python34\Lib\site-packages\pyramid\router.py", line 158, in handle_request
view_name
File "C:\Python34\Lib\site-packages\pyramid\view.py", line 547, in _call_view
response = view_callable(context, request)
File "C:\Python34\Lib\site-packages\pyramid\viewderivers.py", line 442, in rendered_view
result = view(context, request)
File "C:\Python34\Lib\site-packages\pyramid\viewderivers.py", line 147, in _requestonly_view
response = view(request)
File "c:\projects\turing_chat\turing_blog\turing_blog\views\default.py", line 9, in index_page
paginator = BlogRecordService.get_paginator(request, page)
File "c:\projects\turing_chat\turing_blog\turing_blog\services\blog_record.py", line 30, in get_paginator
url_maker=url_maker)
File "C:\Python34\Lib\site-packages\paginate_sqlalchemy\__init__.py", line 35, in __init__
super(SqlalchemyOrmPage, self).__init__(*args, wrapper_class=SqlalchemyOrmWrapper, **kwargs)
File "C:\Python34\Lib\site-packages\paginate\__init__.py", line 251, in __init__
self.items = list(self.collection[first:last])
File "C:\Python34\Lib\site-packages\paginate_sqlalchemy\__init__.py", line 20, in __getitem__
return self.obj[range]
File "C:\Python34\Lib\site-packages\sqlalchemy\orm\query.py", line 2489, in __getitem__
return list(res)
File "C:\Python34\Lib\site-packages\sqlalchemy\orm\query.py", line 2797, in __iter__
return self._execute_and_instances(context)
File "C:\Python34\Lib\site-packages\sqlalchemy\orm\query.py", line 2820, in _execute_and_instances
result = conn.execute(querycontext.statement, self._params)
File "C:\Python34\Lib\site-packages\sqlalchemy\engine\base.py", line 945, in execute
return meth(self, multiparams, params)
File "C:\Python34\Lib\site-packages\sqlalchemy\sql\elements.py", line 263, in _execute_on_connection
return connection._execute_clauseelement(self, multiparams, params)
File "C:\Python34\Lib\site-packages\sqlalchemy\engine\base.py", line 1053, in _execute_clauseelement
compiled_sql, distilled_params
File "C:\Python34\Lib\site-packages\sqlalchemy\engine\base.py", line 1189, in _execute_context
context)
File "C:\Python34\Lib\site-packages\sqlalchemy\engine\base.py", line 1393, in _handle_dbapi_exception
exc_info
File "C:\Python34\Lib\site-packages\sqlalchemy\util\compat.py", line 202, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb, cause=cause)
File "C:\Python34\Lib\site-packages\sqlalchemy\util\compat.py", line 185, in reraise
raise value.with_traceback(tb)
File "C:\Python34\Lib\site-packages\sqlalchemy\engine\base.py", line 1182, in _execute_context
context)
File "C:\Python34\Lib\site-packages\sqlalchemy\engine\default.py", line 469, in do_execute
cursor.execute(statement, parameters) sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) no such table: entries [SQL: 'SELECT entries.id AS entries_id, entries.title AS entries_title, entries.body AS entries_body, entries.created AS entries_created, entries.edited AS entries_edited \nFROM entries ORDER BY entries.created DESC\n LIMIT ? OFFSET ?'] [parameters: (5, 0)]
Expected Result: The tutorial states that I should be seeing a page with text that reads: "No blog entries are found" when I open my localhost address.
These are the file contents of some of the files I created / edited as part of tutorial:
blog_record.py
> import sqlalchemy as sa from paginate_sqlalchemy import
> SqlalchemyOrmPage #<- provides pagination from ..models.blog_record
> import BlogRecord
>
>
> class BlogRecordService(object):
>
> #classmethod
> def all(cls, request):
> query = request.dbsession.query(BlogRecord)
> return query.order_by(sa.desc(BlogRecord.created)) # ^^ will return a query object that can return an entire dataset(in desc order)
> when needed.
> #classmethod
> def by_id(cls, _id, request):
> query = request.dbsession.query(BlogRecord)
> return query.get(_id) # ^^ return a single entry by id or the None object if nothing is found
> #classmethod
> def get_paginator(cls, request, page=1):
> query = request.dbsession.query(BlogRecord)
> query = query.order_by(sa.desc(BlogRecord.created))
> query_params = request.GET.mixed()
>
> def url_maker(link_page):
> # replace page param with values generated by paginator
> query_params['page'] = link_page
> return request.current_route_url(_query=query_params)
>
> return SqlalchemyOrmPage(query, page, items_per_page=5,
> url_maker=url_maker)
default.py
from pyramid.view import view_config
from ..services.blog_record import BlogRecordService
#view_config(route_name='home',
renderer='pyramid_blogr:templates/index.jinja2')
def index_page(request):
page = int(request.params.get('page', 1))
paginator = BlogRecordService.get_paginator(request, page)
return {'paginator': paginator}
# ^^ We first retrieve from the URL's request object the page number that we want to present to the user.
# If the page number is not present, it defaults to 1.
# The paginator object returned by BlogRecord.get_paginator will then be used in the template
# to build a nice list of entries.
# Everything we return from our views in dictionaries will be available in templates as variables.
# So if we return {'foo':1, 'bar':2}, then we will be able to access the variables
# inside the template directly as foo and bar.
#view_config(route_name='auth', match_param='action=in', renderer='string',
request_method='POST')
#view_config(route_name='auth', match_param='action=out', renderer='string')
def sign_in_out(request):
return {}
user.py
import datetime #<- will be used to set default dates on models
from turing_blog.models.meta import Base #<- we need to import our sqlalchemy metadata from which model classes will inherit
from sqlalchemy import (
Column,
Integer,
Unicode, #<- will provide Unicode field
UnicodeText, #<- will provide Unicode text field
DateTime, #<- time abstraction field
)
class User(Base):
__tablename__ = 'users'
id = Column(Integer, primary_key=True)
name = Column(Unicode(255), unique=True, nullable=False)
password = Column(Unicode(255), nullable=False)
last_logged = Column(DateTime, default=datetime.datetime.utcnow)
models/__init__.py
from sqlalchemy import engine_from_config
from sqlalchemy.orm import sessionmaker
from sqlalchemy.orm import configure_mappers
import zope.sqlalchemy
# import or define all models here to ensure they are attached to the
# Base.metadata prior to any initialization routines
from .user import User
from .blog_record import BlogRecord
# run configure_mappers after defining all of the models to ensure
# all relationships can be setup
configure_mappers()
def get_engine(settings, prefix='sqlalchemy.'):
return engine_from_config(settings, prefix)
def get_session_factory(engine):
factory = sessionmaker()
factory.configure(bind=engine)
return factory
def get_tm_session(session_factory, transaction_manager):
"""
Get a ``sqlalchemy.orm.Session`` instance backed by a transaction.
This function will hook the session to the transaction manager which
will take care of committing any changes.
- When using pyramid_tm it will automatically be committed or aborted
depending on whether an exception is raised.
- When using scripts you should wrap the session in a manager yourself.
For example::
import transaction
engine = get_engine(settings)
session_factory = get_session_factory(engine)
with transaction.manager:
dbsession = get_tm_session(session_factory, transaction.manager)
"""
dbsession = session_factory()
zope.sqlalchemy.register(
dbsession, transaction_manager=transaction_manager)
return dbsession
def includeme(config):
"""
Initialize the model for a Pyramid app.
Activate this setup using ``config.include('turing_blog.models')``.
"""
settings = config.get_settings()
# use pyramid_tm to hook the transaction lifecycle to the request
config.include('pyramid_tm')
session_factory = get_session_factory(get_engine(settings))
config.registry['dbsession_factory'] = session_factory
# make request.dbsession available for use in Pyramid
config.add_request_method(
# r.tm is the transaction manager used by pyramid_tm
lambda r: get_tm_session(session_factory, r.tm),
'dbsession',
reify=True
)
models/blog_record.py
import datetime #<- will be used to set default dates on models
from turing_blog.models.meta import Base #<- we need to import our sqlalchemy metadata from which model classes will inherit
from sqlalchemy import (
Column,
Integer,
Unicode, #<- will provide Unicode field
UnicodeText, #<- will provide Unicode text field
DateTime, #<- time abstraction field
)
from webhelpers2.text import urlify #<- will generate slugs e.g. converts "foo Bar Baz" to "foo-Bar-Baz"
from webhelpers2.date import distance_of_time_in_words #<- human friendly dates
class BlogRecord(Base):
__tablename__ = 'entries'
id = Column(Integer, primary_key=True)
title = Column(Unicode(255), unique=True, nullable=False)
body = Column(UnicodeText, default=u'')
created = Column(DateTime, default=datetime.datetime.utcnow)
edited = Column(DateTime, default=datetime.datetime.utcnow)
#property
def slug(self):
return urlify(self.title)
#property
def created_in_words(self):
return distance_of_time_in_words(self.created,
datetime.datetime.utcnow())
I suspect there is a simple mistake I have made that is causing this error e.g. not installing Pyramid properly. It would be great if someone could assist me. I can provide more details as well.
You need to run initialize_pyramid_blogr_db script that creates database tables.
You should have virtualenv folder somewhere and there is either bin or Scripts folder where Python packages install their command line scripts. Locate initialize_pyramid_blogr_db and full file system path to it.
1) Make sure you have your virtual environment activated (activate.bat)
2) Then run within your project folder::
python \path\bin\initialize_pyramid_blogr_db developmnt.ini
Hello I am trying to change a class in SQLAlchemy because it giving me an error, the error is:
File "<string>", line 2, in __init__
File "C:\Python34\lib\site-packages\sqlalchemy\orm\instrumentation.py", line 324, in _new_state_if_none
state = self._state_constructor(instance, self)
File "C:\Python34\lib\site-packages\sqlalchemy\util\langhelpers.py", line 725, in __get__
obj.__dict__[self.__name__] = result = self.fget(obj)
File "C:\Python34\lib\site-packages\sqlalchemy\orm\instrumentation.py", line 158, in _state_constructor
self.dispatch.first_init(self, self.class_)
File "C:\Python34\lib\site-packages\sqlalchemy\event\attr.py", line 260, in __call__
fn(*args, **kw)
File "C:\Python34\lib\site-packages\sqlalchemy\orm\mapper.py", line 2693, in _event_on_first_init
configure_mappers()
File "C:\Python34\lib\site-packages\sqlalchemy\orm\mapper.py", line 2589, in configure_mappers
mapper._post_configure_properties()
File "C:\Python34\lib\site-packages\sqlalchemy\orm\mapper.py", line 1694, in _post_configure_properties
prop.init()
File "C:\Python34\lib\site-packages\sqlalchemy\orm\interfaces.py", line 144, in init
self.do_init()
File "C:\Python34\lib\site-packages\sqlalchemy\orm\relationships.py", line 1549, in do_init
self._process_dependent_arguments()
File "C:\Python34\lib\site-packages\sqlalchemy\orm\relationships.py", line 1605, in _process_dependent_arguments
self.target = self.mapper.mapped_table
File "C:\Python34\lib\site-packages\sqlalchemy\util\langhelpers.py", line 725, in __get__
obj.__dict__[self.__name__] = result = self.fget(obj)
File "C:\Python34\lib\site-packages\sqlalchemy\orm\relationships.py", line 1535, in mapper
% (self.key, type(argument)))
sqlalchemy.exc.ArgumentError: relationship 'prod_comm_rel' expects a class or a mapper argument (received: <class 'sqlalchemy.sql.schema.Column'>)
But it never change the error keeps comming, this is my class:
class Product(Base):
__tablename__="xxxxxx_reg"
__table_args__ = {"useexisting": True}
id = Column("id",BIGINT, primary_key=True)
name = Column("_name",Text, nullable=False)
code = Column("code", BIGINT, unique=True)
status = Column("status",BIGINT, ForeignKey(Status.code),nullable=False)
description = Column("description",Text, nullable=False)
avatar = Column("avatar", Text, nullable=False)
type = Column("_type",BIGINT, ForeignKey(Type.id),nullable=False)
price = Column("price",Numeric(20,2),nullable=False)
costs = Column("costs",Numeric(20,2),default=0.00)
commCode = Column("commerce", BIGINT, ForeignKey(Commerce.code), nullable=False)
#Relation
prod_status_rel = relationship(Status, backref=backref("Product"))
prod_type_rel = relationship(Type, backref=backref("Product"))
prod_comm_rel = relationship(Commerce, backref=backref("Product"))
def __repr__(self):
return "<Product(id='%s', name='%s', status='%s', description='%s', " \
"type='%s', price='%s', costs='%s', code='%s',commerce='%s')>"%(self.id, self.name,
self.status,self.description,
self.type, self.price, self.costs, self.code, self.commCode)
metadata = MetaData()
product_tbl = Table(__tablename__, metadata,id,name,status,description, type,price, costs, code, commCode)
engine = conection().conORM()
metadata.create_all(engine)
How can I fix this code, because I made the change and when I run the class alone It works, the problem is when i try to run it with the other parts of the codes
I have a product model with a many to many relationship to product_categories as described below:
class Product(Base):
""" The SQLAlchemy declarative model class for a Product object. """
__tablename__ = 'products'
id = Column(Integer, primary_key=True)
part_number = Column(String(10), nullable=False, unique=True)
name = Column(String(80), nullable=False, unique=True)
description = Column(String(2000), nullable=False)
categories = relationship('Category', secondary=product_categories,
backref=backref('categories', lazy='dynamic'))
class Category(Base):
""" The SQLAlchemy declarative model class for a Category object. """
__tablename__ = 'categories'
id = Column(Integer, primary_key=True)
lft = Column(Integer, nullable=False)
rgt = Column(Integer, nullable=False)
name = Column(String(80), nullable=False)
description = Column(String(2000), nullable=False)
order = Column(Integer)
products = relationship('Product', secondary=product_categories,
backref=backref('products', lazy='dynamic', order_by=name))
product_categories = Table('product_categories', Base.metadata,
Column('products_id', Integer, ForeignKey('products.id')),
Column('categories_id', Integer, ForeignKey('categories.id'))
)
Then, I'm trying to delete this object with:
product = DBSession.query(Product).filter_by(name = 'Algaecide').one()
DBSession().delete(product)
But, what I get is the error message StaleDataError: DELETE statement on table 'product_categories' expected to delete 1 row(s); Only 0 were matched.. If you notice, it appears to be running the DELETE statement twice. So, the first time it's successfully removes the product_id from the product_categories table, but then attempts to do it yet again for whatever reason, and then decides it needs to throw an exception because it's not there.
>>> Attempting to delete the product 'Algaecide' assigned to categories: [<myproject.models.category.Category object at 0x106fa9d90>]
21:39:50 INFO [sqlalchemy.engine.base.Engine][Dummy-2] SELECT categories.id AS categories_id, categories.lft AS categories_lft, categories.rgt AS categories_rgt, categories.name AS categories_name, categories.description AS categories_description, categories.`order` AS categories_order
FROM categories, product_categories
WHERE %s = product_categories.products_id AND categories.id = product_categories.categories_id ORDER BY categories.name
21:39:50 INFO [sqlalchemy.engine.base.Engine][Dummy-2] (109L,)
21:39:50 INFO [sqlalchemy.engine.base.Engine][Dummy-2] DELETE FROM product_categories WHERE product_categories.products_id = %s AND product_categories.categories_id = %s
21:39:50 INFO [sqlalchemy.engine.base.Engine][Dummy-2] (109L, 18L)
21:39:50 INFO [sqlalchemy.engine.base.Engine][Dummy-2] DELETE FROM product_categories WHERE product_categories.products_id = %s AND product_categories.categories_id = %s
21:39:50 INFO [sqlalchemy.engine.base.Engine][Dummy-2] (109L, 18L)
21:39:50 INFO [sqlalchemy.engine.base.Engine][Dummy-2] ROLLBACK
21:39:50 ERROR [pyramid_debugtoolbar][Dummy-2] Exception at http://0.0.0.0:6543/product/Algaecide/edit
traceback url: http://0.0.0.0:6543/_debug_toolbar/exception?token=6344937a98ee26992689&tb=4421411920
Traceback (most recent call last):
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/pyramid_debugtoolbar-2.3-py2.7.egg/pyramid_debugtoolbar/toolbar.py", line 178, in toolbar_tween
response = _handler(request)
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/pyramid_debugtoolbar-2.3-py2.7.egg/pyramid_debugtoolbar/panels/performance.py", line 57, in resource_timer_handler
result = handler(request)
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/pyramid/tweens.py", line 21, in excview_tween
response = handler(request)
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/pyramid_tm-0.10-py2.7.egg/pyramid_tm/__init__.py", line 95, in tm_tween
reraise(*exc_info)
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/pyramid_tm-0.10-py2.7.egg/pyramid_tm/__init__.py", line 83, in tm_tween
manager.commit()
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/transaction-1.4.3-py2.7.egg/transaction/_manager.py", line 111, in commit
return self.get().commit()
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/transaction-1.4.3-py2.7.egg/transaction/_transaction.py", line 280, in commit
reraise(t, v, tb)
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/transaction-1.4.3-py2.7.egg/transaction/_transaction.py", line 271, in commit
self._commitResources()
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/transaction-1.4.3-py2.7.egg/transaction/_transaction.py", line 417, in _commitResources
reraise(t, v, tb)
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/transaction-1.4.3-py2.7.egg/transaction/_transaction.py", line 389, in _commitResources
rm.tpc_begin(self)
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/zope.sqlalchemy-0.7.5-py2.7.egg/zope/sqlalchemy/datamanager.py", line 90, in tpc_begin
self.session.flush()
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/SQLAlchemy-0.9.8-py2.7-macosx-10.6-intel.egg/sqlalchemy/orm/session.py", line 1919, in flush
self._flush(objects)
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/SQLAlchemy-0.9.8-py2.7-macosx-10.6-intel.egg/sqlalchemy/orm/session.py", line 2037, in _flush
transaction.rollback(_capture_exception=True)
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/SQLAlchemy-0.9.8-py2.7-macosx-10.6-intel.egg/sqlalchemy/util/langhelpers.py", line 60, in __exit__
compat.reraise(exc_type, exc_value, exc_tb)
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/SQLAlchemy-0.9.8-py2.7-macosx-10.6-intel.egg/sqlalchemy/orm/session.py", line 2001, in _flush
flush_context.execute()
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/SQLAlchemy-0.9.8-py2.7-macosx-10.6-intel.egg/sqlalchemy/orm/unitofwork.py", line 372, in execute
rec.execute(self)
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/SQLAlchemy-0.9.8-py2.7-macosx-10.6-intel.egg/sqlalchemy/orm/unitofwork.py", line 479, in execute
self.dependency_processor.process_deletes(uow, states)
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/SQLAlchemy-0.9.8-py2.7-macosx-10.6-intel.egg/sqlalchemy/orm/dependency.py", line 1023, in process_deletes
secondary_update, secondary_delete)
File "/Users/derek/pyramid/myproject/lib/python2.7/site-packages/SQLAlchemy-0.9.8-py2.7-macosx-10.6-intel.egg/sqlalchemy/orm/dependency.py", line 1111, in _run_crud
result.rowcount)
StaleDataError: DELETE statement on table 'product_categories' expected to delete 1 row(s); Only 0 were matched.
Am I missing some sort of a 'gotcha' in this case? Seems like a pretty standard implementation. Why is it attempting to execute the DELETE statement twice?
After a bit more searching, I found the following link which suggests it's a MySQL bug:
https://groups.google.com/forum/#!topic/sqlalchemy/ajYLEuhEB9k
Thankfully, disabling supports_san_multi_rowcount helped!
engine = engine_from_config(settings, 'sqlalchemy.')
engine.dialect.supports_sane_rowcount = engine.dialect.supports_sane_multi_rowcount = False
Good enough for me for now. Here's another interesting resources I found along the way dealing with postgresql:
https://bitbucket.org/zzzeek/sqlalchemy/issue/3015/deletes-executed-twice-when-using
I have set up a simple system for adding comments to items in my database using a one-to-many relation (one item can have many comments), but I can't seem to get it to work. It should be simple, I know. It's probably something simple that I've overlooked. I would very much appriciate a second set of eyes on this. Can anyone help?
I have a model defined with SQLAlchemy that looks like this:
class Item(Base):
__tablename__ = 'items' # Parent
id = Column(Integer, primary_key=True)
comments = relationship("Comment", backref='items')
class Comment(Base):
__tablename__ = 'comments' # Child
id = Column(Integer, primary_key=True)
comment_text = Column(Text, nullable=False)
item_id = Column(Integer, ForeignKey('items.id'), nullable=False)
def __init__(self, comment_text, item_id):
self.comment_text = comment_text
self.item_id = item_id
In my view, I do some work, then try to add a comment object:
item = DBSession.query(Item).filter(Item.id == item_id).first()
try:
print('Item id:', item.id, 'Comment text:', comment)
print('Item Comments:', item.comments)
cm = Comment(comment_text=comment,
item_id=item.id)
print('a')
item.comments.append(cm)
#DBSession.add(cm)
print('b')
DBSession.commit()
except:
DBSession.rollback()
print('c')
Note that I tried both item.comments.append(cm) and DBSession.add(cm) with identical results. That's why one of the two is commented out in the above code block. I also tried item.comments.append(Comment(...)) with identical results.
Now, when I try to add a comment, I get a stacktrace, culminating in:
sqlalchemy.exc.ResourceClosedError: This transaction is closed
The whole trace, including the debug prints, look like this:
Item id: 1 Comment text: test
Item Comments: []
a
c
Traceback (most recent call last):
File "C:\Python33\lib\wsgiref\handlers.py", line 137, in run
self.result = application(self.environ, self.start_response)
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\pyramid\router.py", line 251, in __call__
response = self.invoke_subrequest(request, use_tweens=True)
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\pyramid\router.py", line 227, in invoke_subrequest
response = handle_request(request)
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\pyramid\tweens.py", line 21, in excview_tween
response = handler(request)
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\pyramid_tm\__init__.py", line 82, in tm_tween
reraise(*exc_info)
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\pyramid_tm\compat.py", line 13, in reraise
raise value
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\pyramid_tm\__init__.py", line 70, in tm_tween
manager.commit()
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\transaction\_manager.py", line 111, in commit
return self.get().commit()
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\transaction\_transaction.py", line 280, in commit
reraise(t, v, tb)
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\transaction\_compat.py", line 55, in reraise
raise value
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\transaction\_transaction.py", line 271, in commit
self._commitResources()
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\transaction\_transaction.py", line 417, in _commitResources
reraise(t, v, tb)
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\transaction\_compat.py", line 55, in reraise
raise value
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\transaction\_transaction.py", line 394, in _commitResources
rm.tpc_vote(self)
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\zope\sqlalchemy\datamanager.py", line 100, in tpc_vote
self.tx.commit()
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\sqlalchemy\orm\session.py", line 352, in commit
self._assert_active(prepared_ok=True)
File "C:\Users\[user]\PYTHON~1.5\lib\site-packages\sqlalchemy\orm\session.py", line 203, in _assert_active
raise sa_exc.ResourceClosedError(closed_msg)
sqlalchemy.exc.ResourceClosedError: This transaction is closed
Well, turns out the problem was a few corrupt files, not a programming error. Sigh. Well, problem solved. :)