Re: [sqlalchemy] Invalidated Collection
Thanks, Mike! I have some studying to do...
On Wednesday, February 3, 2021 at 6:42:17 PM UTC-5 Mike Bayer wrote:
>
>
> On Wed, Feb 3, 2021, at 6:23 PM, Christian Henning wrote:
>
> Hi Mike,
>
> thanks for your advice! I'll make the changes.
>
> But let me ask you one thing. My classmethod create() is but more complex
> than I have posted. It's meant to catch IntegrityError so that unique
> constraints are enforced. Image a User table has a "unique" constraint on
> the name. When I try to create a user with the same name the create() would
> catch the exception and return the original user. I believe this only
> possible when all objects are committed to the database.
>
> class ModelBase:
>
> @classmethod
> def create(cls, session, **kwargs):
> obj = cls(**kwargs)
> try:
> obj.save(session)
> except IntegrityError:
> # print('HOLA - Integrity Error')
>
> session.rollback()
> obj = cls.find(session, **kwargs)
>
> return obj
>
> def save(self, session):
> session.add(self)
> session.commit()
>
> How would you solve the problem? Is there anything in the documentation?
>
>
> yes, use a SAVEPOINT for that, so you can roll back to the savepoint and
> still have the transaction continue:
>
>
> https://docs.sqlalchemy.org/en/13/faq/sessions.html#but-why-does-flush-insist-on-issuing-a-rollback
>
> so you can place in your method:
>
> session.begin_nested():
> session.add(obj)
> try:
> session.flush()
> except IntegrityError:
> session.rollback()
> else:
> session.commit()
>
>
>
>
> Thanks,
> Christian
>
>
>
>
>
> On Wednesday, February 3, 2021 at 5:12:30 PM UTC-5 Mike Bayer wrote:
>
>
> the session.commit() method expires all attributes by default:
>
> https://docs.sqlalchemy.org/en/13/orm/session_basics.html#committing
>
> your code is organized in an unusual way such that transactions are being
> committed inside of attribute assignment operations:
>
> jack.addresses.append(Address.create(session))
>
> We can expand this out as follows:
>
> addr = jack.addresses
> address = Address()
> session.add(address)
> session.commit() # <--- expires all attributes on "jack", "address",
> invalidates "addr"
> attr.append(address) # <--- this is invalid, transaction was already
> commited
>
> I would strongly advise keeping session scope manage external to the set
> of operations you are performing. See
> https://docs.sqlalchemy.org/en/13/orm/session_basics.html#when-do-i-construct-a-session-when-do-i-commit-it-and-when-do-i-close-it
>
> for guidelines.
>
>
> On Wed, Feb 3, 2021, at 2:27 PM, Christian Henning wrote:
>
> I don't understand why SQLAlchemy gives me the following warning:
>
> SAWarning: This collection has been invalidated.
> util.warn("This collection has been invalidated.")
>
> Here is a minimal code example:
>
> -
> -
>
> import sqlalchemy
> print(sqlalchemy.__version__)
>
> from sqlalchemy import create_engine
> from sqlalchemy import Column, Integer, ForeignKey
>
> from sqlalchemy.exc import IntegrityError
> from sqlalchemy.ext.declarative import declarative_base
>
> from sqlalchemy.orm import relationship
> from sqlalchemy.orm import sessionmaker
>
> Base = declarative_base()
>
> class ModelBase:
>
> @classmethod
> def create(cls, session, **kwargs):
> obj = cls(**kwargs)
> session.add(obj)
> session.commit()
>
> return obj
>
>
> class User(ModelBase, Base):
> __tablename__ = 'users'
>
> id = Column(Integer, primary_key=True)
>
> addresses = relationship("Address", order_by="Address.id",
> back_populates="user")
>
> class Address(ModelBase, Base):
> __tablename__ = 'addresses'
>
> id = Column(Integer, primary_key=True)
>
> user_id = Column(Integer, ForeignKey('users.id'))
>
> user = relationship("User", back_populates="addresses")
>
>
> engine = create_engine('sqlite:///:memory:', echo=False)
> Base.metadata.create_all(engine)
>
> Session = sessionmaker(bind=engine)
> session = Session()
>
> jack = User.create(session)
> jack.addresses.append(Address.create(session))
>
> -
> -
> I have tested the code with SQLAlchemy for 1.3.18 and 1.4.0b1. I'm using
> python 3.9.1
>
> When I rewrite the last few lines a bit the warning disappears. For
> instance:
>
> jack = User.create(session)
> a = Address.create(session)
> jack.addresses.append(a)
>
>
> Any insight is appreciated. I'm still learning.
>
> Thanks,
> Christian
>
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
> ---
> You received this message because you are subscribed to the Google Groups
> "sqlalchemy" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to
Re: [sqlalchemy] Invalidated Collection
On Wed, Feb 3, 2021, at 6:23 PM, Christian Henning wrote:
> Hi Mike,
>
> thanks for your advice! I'll make the changes.
>
> But let me ask you one thing. My classmethod create() is but more complex
> than I have posted. It's meant to catch IntegrityError so that unique
> constraints are enforced. Image a User table has a "unique" constraint on the
> name. When I try to create a user with the same name the create() would catch
> the exception and return the original user. I believe this only possible when
> all objects are committed to the database.
>
> class ModelBase:
>
> @classmethod
> def create(cls, session, **kwargs):
> obj = cls(**kwargs)
> try:
> obj.save(session)
> except IntegrityError:
> # print('HOLA - Integrity Error')
>
> session.rollback()
> obj = cls.find(session, **kwargs)
>
> return obj
>
> def save(self, session):
> session.add(self)
> session.commit()
>
> How would you solve the problem? Is there anything in the documentation?
yes, use a SAVEPOINT for that, so you can roll back to the savepoint and still
have the transaction continue:
https://docs.sqlalchemy.org/en/13/faq/sessions.html#but-why-does-flush-insist-on-issuing-a-rollback
so you can place in your method:
session.begin_nested():
session.add(obj)
try:
session.flush()
except IntegrityError:
session.rollback()
else:
session.commit()
>
> Thanks,
> Christian
>
>
>
>
>
> On Wednesday, February 3, 2021 at 5:12:30 PM UTC-5 Mike Bayer wrote:
>> __
>> the session.commit() method expires all attributes by default:
>>
>> https://docs.sqlalchemy.org/en/13/orm/session_basics.html#committing
>>
>> your code is organized in an unusual way such that transactions are being
>> committed inside of attribute assignment operations:
>>
>> jack.addresses.append(Address.create(session))
>>
>> We can expand this out as follows:
>>
>> addr = jack.addresses
>> address = Address()
>> session.add(address)
>> session.commit() # <--- expires all attributes on "jack", "address",
>> invalidates "addr"
>> attr.append(address) # <--- this is invalid, transaction was already
>> commited
>>
>> I would strongly advise keeping session scope manage external to the set of
>> operations you are performing. See
>> https://docs.sqlalchemy.org/en/13/orm/session_basics.html#when-do-i-construct-a-session-when-do-i-commit-it-and-when-do-i-close-it
>> for guidelines.
>>
>>
>> On Wed, Feb 3, 2021, at 2:27 PM, Christian Henning wrote:
>>> I don't understand why SQLAlchemy gives me the following warning:
>>>
>>> SAWarning: This collection has been invalidated.
>>> util.warn("This collection has been invalidated.")
>>>
>>> Here is a minimal code example:
>>>
>>> -
>>> -
>>>
>>> import sqlalchemy
>>> print(sqlalchemy.__version__)
>>>
>>> from sqlalchemy import create_engine
>>> from sqlalchemy import Column, Integer, ForeignKey
>>>
>>> from sqlalchemy.exc import IntegrityError
>>> from sqlalchemy.ext.declarative import declarative_base
>>>
>>> from sqlalchemy.orm import relationship
>>> from sqlalchemy.orm import sessionmaker
>>>
>>> Base = declarative_base()
>>>
>>> class ModelBase:
>>>
>>> @classmethod
>>> def create(cls, session, **kwargs):
>>> obj = cls(**kwargs)
>>> session.add(obj)
>>> session.commit()
>>>
>>> return obj
>>>
>>>
>>> class User(ModelBase, Base):
>>> __tablename__ = 'users'
>>>
>>> id = Column(Integer, primary_key=True)
>>>
>>> addresses = relationship("Address", order_by="Address.id",
>>> back_populates="user")
>>>
>>> class Address(ModelBase, Base):
>>> __tablename__ = 'addresses'
>>>
>>> id = Column(Integer, primary_key=True)
>>>
>>> user_id = Column(Integer, ForeignKey('users.id'))
>>>
>>> user = relationship("User", back_populates="addresses")
>>>
>>>
>>> engine = create_engine('sqlite:///:memory:', echo=False)
>>> Base.metadata.create_all(engine)
>>>
>>> Session = sessionmaker(bind=engine)
>>> session = Session()
>>>
>>> jack = User.create(session)
>>> jack.addresses.append(Address.create(session))
>>>
>>> -
>>> -
>>> I have tested the code with SQLAlchemy for 1.3.18 and 1.4.0b1. I'm using
>>> python 3.9.1
>>>
>>> When I rewrite the last few lines a bit the warning disappears. For
>>> instance:
>>>
>>> jack = User.create(session)
>>> a = Address.create(session)
>>> jack.addresses.append(a)
>>>
>>>
>>> Any insight is appreciated. I'm still learning.
>>>
>>> Thanks,
>>> Christian
>>>
>>>
>>>
>>> --
>>> SQLAlchemy -
>>> The Python SQL Toolkit and Object Relational Mapper
>>>
>>> http://www.sqlalchemy.org/
>>>
>>> To post example code, please provide an MCVE: Minimal, Complete, and
>>> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
>>> description.
>>> ---
>>> You received this message because you are subscribed to the Google Groups
>>> "sqlalchemy" group.
Re: [sqlalchemy] Invalidated Collection
Hi Mike,
thanks for your advice! I'll make the changes.
But let me ask you one thing. My classmethod create() is but more complex
than I have posted. It's meant to catch IntegrityError so that unique
constraints are enforced. Image a User table has a "unique" constraint on
the name. When I try to create a user with the same name the create() would
catch the exception and return the original user. I believe this only
possible when all objects are committed to the database.
class ModelBase:
@classmethod
def create(cls, session, **kwargs):
obj = cls(**kwargs)
try:
obj.save(session)
except IntegrityError:
# print('HOLA - Integrity Error')
session.rollback()
obj = cls.find(session, **kwargs)
return obj
def save(self, session):
session.add(self)
session.commit()
How would you solve the problem? Is there anything in the documentation?
Thanks,
Christian
On Wednesday, February 3, 2021 at 5:12:30 PM UTC-5 Mike Bayer wrote:
> the session.commit() method expires all attributes by default:
>
> https://docs.sqlalchemy.org/en/13/orm/session_basics.html#committing
>
> your code is organized in an unusual way such that transactions are being
> committed inside of attribute assignment operations:
>
> jack.addresses.append(Address.create(session))
>
> We can expand this out as follows:
>
> addr = jack.addresses
> address = Address()
> session.add(address)
> session.commit() # <--- expires all attributes on "jack", "address",
> invalidates "addr"
> attr.append(address) # <--- this is invalid, transaction was already
> commited
>
> I would strongly advise keeping session scope manage external to the set
> of operations you are performing. See
> https://docs.sqlalchemy.org/en/13/orm/session_basics.html#when-do-i-construct-a-session-when-do-i-commit-it-and-when-do-i-close-it
>
> for guidelines.
>
>
> On Wed, Feb 3, 2021, at 2:27 PM, Christian Henning wrote:
>
> I don't understand why SQLAlchemy gives me the following warning:
>
> SAWarning: This collection has been invalidated.
> util.warn("This collection has been invalidated.")
>
> Here is a minimal code example:
>
> -
> -
>
> import sqlalchemy
> print(sqlalchemy.__version__)
>
> from sqlalchemy import create_engine
> from sqlalchemy import Column, Integer, ForeignKey
>
> from sqlalchemy.exc import IntegrityError
> from sqlalchemy.ext.declarative import declarative_base
>
> from sqlalchemy.orm import relationship
> from sqlalchemy.orm import sessionmaker
>
> Base = declarative_base()
>
> class ModelBase:
>
> @classmethod
> def create(cls, session, **kwargs):
> obj = cls(**kwargs)
> session.add(obj)
> session.commit()
>
> return obj
>
>
> class User(ModelBase, Base):
> __tablename__ = 'users'
>
> id = Column(Integer, primary_key=True)
>
> addresses = relationship("Address", order_by="Address.id",
> back_populates="user")
>
> class Address(ModelBase, Base):
> __tablename__ = 'addresses'
>
> id = Column(Integer, primary_key=True)
>
> user_id = Column(Integer, ForeignKey('users.id'))
>
> user = relationship("User", back_populates="addresses")
>
>
> engine = create_engine('sqlite:///:memory:', echo=False)
> Base.metadata.create_all(engine)
>
> Session = sessionmaker(bind=engine)
> session = Session()
>
> jack = User.create(session)
> jack.addresses.append(Address.create(session))
>
> -
> -
> I have tested the code with SQLAlchemy for 1.3.18 and 1.4.0b1. I'm using
> python 3.9.1
>
> When I rewrite the last few lines a bit the warning disappears. For
> instance:
>
> jack = User.create(session)
> a = Address.create(session)
> jack.addresses.append(a)
>
>
> Any insight is appreciated. I'm still learning.
>
> Thanks,
> Christian
>
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
> ---
> You received this message because you are subscribed to the Google Groups
> "sqlalchemy" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to sqlalchemy+...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/sqlalchemy/7a369ff7-659c-4ee4-a8d0-a786ec3579aen%40googlegroups.com
>
>
> .
>
>
>
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
---
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To
Re: [sqlalchemy] Invalidated Collection
the session.commit() method expires all attributes by default:
https://docs.sqlalchemy.org/en/13/orm/session_basics.html#committing
your code is organized in an unusual way such that transactions are being
committed inside of attribute assignment operations:
jack.addresses.append(Address.create(session))
We can expand this out as follows:
addr = jack.addresses
address = Address()
session.add(address)
session.commit() # <--- expires all attributes on "jack", "address",
invalidates "addr"
attr.append(address) # <--- this is invalid, transaction was already
commited
I would strongly advise keeping session scope manage external to the set of
operations you are performing. See
https://docs.sqlalchemy.org/en/13/orm/session_basics.html#when-do-i-construct-a-session-when-do-i-commit-it-and-when-do-i-close-it
for guidelines.
On Wed, Feb 3, 2021, at 2:27 PM, Christian Henning wrote:
> I don't understand why SQLAlchemy gives me the following warning:
>
> SAWarning: This collection has been invalidated.
> util.warn("This collection has been invalidated.")
>
> Here is a minimal code example:
>
> -
> -
>
> import sqlalchemy
> print(sqlalchemy.__version__)
>
> from sqlalchemy import create_engine
> from sqlalchemy import Column, Integer, ForeignKey
>
> from sqlalchemy.exc import IntegrityError
> from sqlalchemy.ext.declarative import declarative_base
>
> from sqlalchemy.orm import relationship
> from sqlalchemy.orm import sessionmaker
>
> Base = declarative_base()
>
> class ModelBase:
>
> @classmethod
> def create(cls, session, **kwargs):
> obj = cls(**kwargs)
> session.add(obj)
> session.commit()
>
> return obj
>
>
> class User(ModelBase, Base):
> __tablename__ = 'users'
>
> id = Column(Integer, primary_key=True)
>
> addresses = relationship("Address", order_by="Address.id",
> back_populates="user")
>
> class Address(ModelBase, Base):
> __tablename__ = 'addresses'
>
> id = Column(Integer, primary_key=True)
>
> user_id = Column(Integer, ForeignKey('users.id'))
>
> user = relationship("User", back_populates="addresses")
>
>
> engine = create_engine('sqlite:///:memory:', echo=False)
> Base.metadata.create_all(engine)
>
> Session = sessionmaker(bind=engine)
> session = Session()
>
> jack = User.create(session)
> jack.addresses.append(Address.create(session))
>
> -
> -
> I have tested the code with SQLAlchemy for 1.3.18 and 1.4.0b1. I'm using
> python 3.9.1
>
> When I rewrite the last few lines a bit the warning disappears. For instance:
>
> jack = User.create(session)
> a = Address.create(session)
> jack.addresses.append(a)
>
>
> Any insight is appreciated. I'm still learning.
>
> Thanks,
> Christian
>
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
> ---
> You received this message because you are subscribed to the Google Groups
> "sqlalchemy" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to sqlalchemy+unsubscr...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/sqlalchemy/7a369ff7-659c-4ee4-a8d0-a786ec3579aen%40googlegroups.com
>
> .
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
---
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sqlalchemy+unsubscr...@googlegroups.com.
To view this discussion on the web visit
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[sqlalchemy] Invalidated Collection
I don't understand why SQLAlchemy gives me the following warning:
SAWarning: This collection has been invalidated.
util.warn("This collection has been invalidated.")
Here is a minimal code example:
-
-
import sqlalchemy
print(sqlalchemy.__version__)
from sqlalchemy import create_engine
from sqlalchemy import Column, Integer, ForeignKey
from sqlalchemy.exc import IntegrityError
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship
from sqlalchemy.orm import sessionmaker
Base = declarative_base()
class ModelBase:
@classmethod
def create(cls, session, **kwargs):
obj = cls(**kwargs)
session.add(obj)
session.commit()
return obj
class User(ModelBase, Base):
__tablename__ = 'users'
id = Column(Integer, primary_key=True)
addresses = relationship("Address", order_by="Address.id",
back_populates="user")
class Address(ModelBase, Base):
__tablename__ = 'addresses'
id = Column(Integer, primary_key=True)
user_id = Column(Integer, ForeignKey('users.id'))
user = relationship("User", back_populates="addresses")
engine = create_engine('sqlite:///:memory:', echo=False)
Base.metadata.create_all(engine)
Session = sessionmaker(bind=engine)
session = Session()
jack = User.create(session)
jack.addresses.append(Address.create(session))
-
-
I have tested the code with SQLAlchemy for 1.3.18 and 1.4.0b1. I'm using
python 3.9.1
When I rewrite the last few lines a bit the warning disappears. For
instance:
jack = User.create(session)
a = Address.create(session)
jack.addresses.append(a)
Any insight is appreciated. I'm still learning.
Thanks,
Christian
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
---
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