On Mon, Mar 18, 2019 at 11:07 AM Денис Ралко <ralk...@gmail.com> wrote:
>
> Thx for your quick answer.
> About second question
>
> I have event, for example
>
> def track_instances_before_flush(session, context, instances):
> for obj in chain(session.new, session.dirty):
> if session.is_modified(obj):
> print "Before Flush"
>
> table_name = obj.__class__.__dict__['__tablename__']
>
> print "Table_name ---", table_name
>
>
> print "Raw obj - ", obj
>
> state_before = {}
> state_after = {}
> mapper = inspect(obj)
> attrs = class_mapper(obj.__class__).column_attrs
>
> for attr in attrs:
> hist = mapper.attrs[attr.key].history
> if hist.has_changes():
> state_before[attr.key] = get_history(obj, attr.key)[2][0]
> state_after[attr.key] = getattr(obj, attr.key)
>
> print "BEFORE -", state_before
> print "AFTER -", state_after
>
>
>
> and register it by
>
> listen(app.db.session, 'before_flush', track_instances_before_flush)
the code you've sent is still incomplete, for example i dont know what
"Site" is, but if you want to track relationships you need to look at
mapper.attrs or mapper.relationship_attrs. POC below with what I
could derive from your code fragments.
from __future__ import print_function
from itertools import chain
from sqlalchemy import Column
from sqlalchemy import create_engine
from sqlalchemy import ForeignKey
from sqlalchemy import inspect
from sqlalchemy import Integer
from sqlalchemy import Table
from sqlalchemy import UniqueConstraint
from sqlalchemy.event import listen
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import class_mapper
from sqlalchemy.orm import relationship
from sqlalchemy.orm import Session
Base = declarative_base()
class MODEL_1(Base):
__tablename__ = "MODEL_1"
entity_id = Column(Integer, primary_key=True)
# Don't know what "Site" is
# attr_1 = relationship(
# "MODEL_2",
# secondary="test2test",
# lazy="dynamic",
# primaryjoin="MODEL_1.id == test2test.c.first_id",
# secondaryjoin="test2test.c.second_id == Site.entity_id",
# )
class MODEL_2(Base):
__tablename__ = "MODEL_2"
id = Column(Integer, primary_key=True)
attr_2 = relationship("MODEL_1", secondary="test2test", lazy="dynamic")
t_ = Table(
"test2test",
Base.metadata,
Column(
"first_id", Integer, ForeignKey("MODEL_1.entity_id"), nullable=False
),
Column("second_id", Integer, ForeignKey("MODEL_2.id"), nullable=False),
UniqueConstraint("first_id", "second_id", name="uq_test2test"),
)
def track_instances_before_flush(session, context, instances):
for obj in chain(session.new, session.dirty):
if session.is_modified(obj):
print("Before Flush")
table_name = obj.__class__.__dict__["__tablename__"]
print("Table_name ---", table_name)
print("Raw obj - ", obj)
state_before = {}
state_after = {}
mapper = inspect(obj)
attrs = class_mapper(obj.__class__).attrs
for attr in attrs:
hist = mapper.attrs[attr.key].history
if hist.has_changes():
state_before[attr.key] = hist[2] or hist[1]
state_after[attr.key] = hist[0]
print("BEFORE -", state_before)
print("AFTER -", state_after)
e = create_engine("sqlite://", echo=True)
Base.metadata.create_all(e)
s = Session(e)
listen(s, "before_flush", track_instances_before_flush)
m1 = MODEL_1()
m2 = MODEL_2()
s.add_all([m1, m2])
s.commit()
print("------------------")
m2.attr_2.append(m1)
s.commit()
>
>
> and in output i see
> Before Flush
> Table_name --- MODEL_1
> Raw obj - <'MODEL_1' id=2050>
>
> BEFORE - {}
> AFTER - {}
>
> In view I change only attr_1 for MODEL_1
>
> On Monday, March 18, 2019 at 4:48:00 PM UTC+2, Mike Bayer wrote:
>>
>> On Mon, Mar 18, 2019 at 10:30 AM Денис Ралко <ral...@gmail.com> wrote:
>> >
>> > Hi, I have some issue
>> >
>> > I try implement track logic
>> > I have 2 Models and connecting Table
>> >
>> > My first class
>> >
>> > class MODEL_1(object):
>> > # some values
>> >
>> > # relations:
>> > attr_1 = db.relationship('MODEL_2',
>> > secondary="test2test",
>> > lazy='dynamic',
>> > primaryjoin="MODEL_1.id ==
>> > test2test.c.first_id",
>> > secondaryjoin='test2test.c.second_id ==
>> > Site.entity_id')
>> >
>> > Second class
>> >
>> > class MODEL_2(object):
>> > # some values
>> > attr_2 = db.relationship('MODEL_1', secondary='test2test',
>> > lazy='dynamic')
>> >
>> >
>> > And relation table
>> >
>> >
>> > t_ = db.Table(
>> > 'test2test',
>> > db.Model.metadata,
>> >
>> > db.Column('first_id', db.Integer,
>> > db.ForeignKey('MODEL_1.entity_id'),
>> > nullable=False),
>> > db.Column('second_id', db.Integer,
>> > db.ForeignKey('MODEL_2.id'),
>> > nullable=False),
>> > db.UniqueConstraint('first_id', 'second_id', name='uq_test2test')
>> > )
>> >
>> >
>> > I have some questions
>> >
>> > 1. can i do some table event what will fire, when will change some values
>> > in t_ table ?
>>
>> via the relationship, sure, use @validates or AttributeEvents for
>> MODEL_1.attr1, MODEL_2.attr2
>>
>> https://docs.sqlalchemy.org/en/latest/orm/events.html?highlight=attributeevents#sqlalchemy.orm.events.AttributeEvents
>>
>>
>> >
>> > 2. if i set before_flush event and change some in MODEL_1, event fire, but
>> > session have no modified objects
>>
>> you would need to send along a complete example illustrating what you're
>> doing.
>>
>>
>>
>> >
>> > --
>> > 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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>
> --
> 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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--
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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