[sqlalchemy] Event do not fire on m2m relation
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 ?
2. if i set before_flush event and change some in MODEL_1, event fire, but
session have no modified objects
--
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The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
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Re: [sqlalchemy] Event do not fire on m2m relation
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)
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 > 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.
> > ---
> > 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 post to this group, send email to sqlal...@googlegroups.com
> .
> > Visit this group at https://groups.google.com/group/sqlalchemy.
> > For more options, visit https://groups.google.com/d/optout.
>
--
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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Re: [sqlalchemy] Event do not fire on m2m relation
Sorry, my mistake
Site.entity_id == MODEL_2.id
And I solve my problem by change mapper.attrs -> mapper.column_attrs
And now I want to ask you
Can event directly set on Table colums?
On Monday, March 18, 2019 at 10:28:54 PM UTC+2, Mike Bayer wrote:
>
> On Mon, Mar 18, 2019 at 11:07 AM Денис Ралко > 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 =
