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1.1 regression due to TypeDecorator copy() from Column.copy(), interferes with mutable #3950

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sqlalchemy-bot opened this issue Mar 30, 2017 · 4 comments
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1.1 regression due to TypeDecorator copy() from Column.copy(), interferes with mutable #3950

sqlalchemy-bot opened this issue Mar 30, 2017 · 4 comments
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blocker issue that must be resolved asap as it is preventing things from working bug Something isn't working sqlalchemy.ext extension modules, most of which are ORM related
Milestone
1.1.xx

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Migrated issue, originally created by Michael Bayer (@zzzeek)

this is a bug that exists since sqlalchemy.ext.mutable started, however it only is apparent when the type object is copied. The copy is uncommon except in the case of SchemaEventTarget, which TypeDecorator becomes in 1.1.

from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base
import json
from sqlalchemy.ext import mutable

Base = declarative_base()


class MyType(TypeDecorator):
    impl = Text

    def process_bind_param(self, value, dialect):
        if value is not None:
            value = json.dumps(value)
        return value

    def process_result_value(self, value, dialect):
        if value is not None:
            value = json.loads(value)
        return value

data = Column(mutable.MutableDict.as_mutable(MyType))


class A(Base):
    __tablename__ = 'a'
    id = Column(Integer, primary_key=True)

    # works fine
    # data = data

    # fails in 1.1 because TypeDecorator is a SchemaType,
    # so Column copies the type, so the event we attached
    # to scan mapper columns can't identify that this is the "data"
    # we copied
    data = data.copy()  # as happens in declarative

e = create_engine("sqlite://", echo=True)
Base.metadata.create_all(e)

s = Session(e)

a1 = A(data={"foo": "bar"})
s.add(a1)
s.commit()

a1.data["foo"] = "bat"
s.commit()

assert a1.data["foo"] == "bat"
@sqlalchemy-bot
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Michael Bayer (@zzzeek) wrote:

https://gerrit.sqlalchemy.org/364

@sqlalchemy-bot
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Michael Bayer (@zzzeek) wrote:

Track SchemaEventTarget types in as_mutable()

Fixed bug in :mod:sqlalchemy.ext.mutable where the
:meth:.Mutable.as_mutable method would not track a type that had
been copied using :meth:.TypeEngine.copy. This became more of
a regression in 1.1 compared to 1.0 because the :class:.TypeDecorator
class is now a subclass of :class:.SchemaEventTarget, which among
other things indicates to the parent :class:.Column that the type
should be copied when the :class:.Column is. These copies are
common when using declarative with mixins or abstract classes.

Change-Id: Ib04df862c58263185dbae686c548fea3e12c46f1
Fixes: #3950

→ 07b6389

@sqlalchemy-bot
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Michael Bayer (@zzzeek) wrote:

Track SchemaEventTarget types in as_mutable()

Fixed bug in :mod:sqlalchemy.ext.mutable where the
:meth:.Mutable.as_mutable method would not track a type that had
been copied using :meth:.TypeEngine.copy. This became more of
a regression in 1.1 compared to 1.0 because the :class:.TypeDecorator
class is now a subclass of :class:.SchemaEventTarget, which among
other things indicates to the parent :class:.Column that the type
should be copied when the :class:.Column is. These copies are
common when using declarative with mixins or abstract classes.

Change-Id: Ib04df862c58263185dbae686c548fea3e12c46f1
Fixes: #3950
(cherry picked from commit 07b6389)

→ 502a46b

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Changes by Michael Bayer (@zzzeek):

  • changed status to closed

@sqlalchemy-bot sqlalchemy-bot added bug Something isn't working sqlalchemy.ext extension modules, most of which are ORM related blocker issue that must be resolved asap as it is preventing things from working labels Nov 27, 2018
@sqlalchemy-bot sqlalchemy-bot added this to the 1.1.x milestone Nov 27, 2018
@sqlalchemy-bot sqlalchemy-bot mentioned this issue Nov 27, 2018
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blocker issue that must be resolved asap as it is preventing things from working bug Something isn't working sqlalchemy.ext extension modules, most of which are ORM related
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