Just curious. Let's say we have a complex primary key of user_id (integer),
project_id (integer) and date (timestamp). After adding and committing we
don't have the PK and we won't be able to update it. Is that right?
If it was auto-increment integer then it would probably be fine. PK would
be fetched using last_inster_id() in mysql or similar method in other
dialects.
from sqlalchemy import create_engine, Column, Integer, TIMESTAMP,
FetchedValue
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
Base = declarative_base()
engine =
create_engine('mysql+mysqldb://root:****@192.168.1.12:3306/test?charset=utf8',
echo=True)
class Timesheet(Base):
__tablename__ = 'timesheet'
user_id = Column(Integer, primary_key=True)
project_id = Column(Integer, primary_key=True)
date = Column(TIMESTAMP(), primary_key=True, nullable=False,
server_default=FetchedValue())
session = sessionmaker(engine)()
t1 = Timesheet(user_id=1, project_id=1)
session.add(t1)
session.commit()
print t1.date
2017-05-15 11:46:09,411 INFO sqlalchemy.engine.base.Engine SHOW VARIABLES
LIKE 'sql_mode'
2017-05-15 11:46:09,411 INFO sqlalchemy.engine.base.Engine ()
2017-05-15 11:46:09,412 INFO sqlalchemy.engine.base.Engine SELECT DATABASE()
2017-05-15 11:46:09,412 INFO sqlalchemy.engine.base.Engine ()
2017-05-15 11:46:09,412 INFO sqlalchemy.engine.base.Engine show collation
where `Charset` = 'utf8' and `Collation` = 'utf8_bin'
2017-05-15 11:46:09,413 INFO sqlalchemy.engine.base.Engine ()
2017-05-15 11:46:09,413 INFO sqlalchemy.engine.base.Engine SELECT
CAST('test plain returns' AS CHAR(60)) AS anon_1
2017-05-15 11:46:09,413 INFO sqlalchemy.engine.base.Engine ()
2017-05-15 11:46:09,414 INFO sqlalchemy.engine.base.Engine SELECT
CAST('test unicode returns' AS CHAR(60)) AS anon_1
2017-05-15 11:46:09,414 INFO sqlalchemy.engine.base.Engine ()
2017-05-15 11:46:09,414 INFO sqlalchemy.engine.base.Engine SELECT
CAST('test collated returns' AS CHAR CHARACTER SET utf8) COLLATE utf8_bin
AS anon_1
2017-05-15 11:46:09,414 INFO sqlalchemy.engine.base.Engine ()
2017-05-15 11:46:09,415 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2017-05-15 11:46:09,416 INFO sqlalchemy.engine.base.Engine INSERT INTO
timesheet (user_id, project_id) VALUES (%s, %s)
2017-05-15 11:46:09,416 INFO sqlalchemy.engine.base.Engine (1, 1)
2017-05-15 11:46:09,416 INFO sqlalchemy.engine.base.Engine COMMIT
Traceback (most recent call last):
File "/home/mike/projects/sandbox/box7.py", line 21, in <module>
print t1.date
File
"/home/mike/envs/slashdb9/local/lib/python2.7/site-packages/sqlalchemy/orm/attributes.py",
line 237, in __get__
return self.impl.get(instance_state(instance), dict_)
File
"/home/mike/envs/slashdb9/local/lib/python2.7/site-packages/sqlalchemy/orm/attributes.py",
line 578, in get
value = state._load_expired(state, passive)
File
"/home/mike/envs/slashdb9/local/lib/python2.7/site-packages/sqlalchemy/orm/state.py",
line 474, in _load_expired
self.manager.deferred_scalar_loader(self, toload)
File
"/home/mike/envs/slashdb9/local/lib/python2.7/site-packages/sqlalchemy/orm/loading.py",
line 669, in load_scalar_attributes
raise orm_exc.ObjectDeletedError(state)
sqlalchemy.orm.exc.ObjectDeletedError: Instance '<Timesheet at
0x7f9ad5931d50>' has been deleted, or its row is otherwise not present.
2017-05-15 11:46:09,419 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2017-05-15 11:46:09,420 INFO sqlalchemy.engine.base.Engine SELECT
timesheet.user_id AS timesheet_user_id, timesheet.project_id AS
timesheet_project_id, timesheet.date AS timesheet_date
FROM timesheet
WHERE timesheet.user_id = %s AND timesheet.project_id = %s AND
timesheet.date IS NULL
2017-05-15 11:46:09,420 INFO sqlalchemy.engine.base.Engine (1, 1)
--
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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