Kent wrote:
> Thanks for your prompt response.
>
> Assuming I fully compose the primary keys, I am still struggling with
> merge():
>
> The model is exactly as I've pasted in my original post, except that
> I've changed the mapper to cascade delete and delete-orphan, since I
> read it would solve my issue...
>
> So the new mapper is:
>
> =======
> orderdetail_mapper = mapper(OrderDetail, order_detail_table,
> properties=dict(parentorder=relation(Order,
> cascade='all,delete-orphan',single_parent=True,
> backref='orderdetails')))
oh, sorry, you have "cascade" on the wrong side. the parent->child for
"orphan" is Order->OrderDetail, so the cascade needs to be on
"orderdetails" for the orphan to take place.
Also I wonder how single_parent=True came to be there ? Oh i guess
because of the erroneous "delete-orphan"...you can take that out too.
> =======
>
> Start over with a fresh database. Now, I add two "line details" like
> my original post.
>
>
> ================
> ord = Order()
> ord.id = '55'
> ord.customer = 'Kent'
>
> ln1 = OrderDetail()
> ln1.line = 1
> ln1.orderid = '55'
> ln1.product = 'DESK'
>
> ln2 = OrderDetail()
> ln2.line = 2
> ln2.orderid = '55'
> ln2.product = 'WHITESECTIONAL'
>
> ord.orderdetails = [ln1,ln2]
>
> session.add(ord)
> session.flush()
> session.commit()
> ==================
>
>
> This behaves as I expected.
>
> Now, onto merge. Say that ln1 has been deleted and ln3 added:
>
>
> ====
> ord = Order()
> ord.id = '55'
> ord.customer = 'Kent'
>
> ln2 = OrderDetail()
> ln2.line = 2
> ln2.orderid = '55'
> ln2.product = 'WHITESECTIONAL'
>
> ln3 = OrderDetail() # new line
> ln3.line = 3
> ln3.orderid = '55'
> ln3.product = 'CHAIR'
>
> ord.orderdetails = [ln2,ln3]
>
> dbord = session.merge(ord)
> session.commit()
> ======
>
>
> I expected merge to INSERT ln3 (which it attempts to do) and DELETE
> ln1, which it doesn't do, but fails with this exception:
>
> AssertionError: Dependency rule tried to blank-out primary key column
> 'orderdetails.orderid' on instance '<OrderDetail at 0x2cc5850>'
>
>
> Is my use-case for merge() still not really what it was designed for?
> Can you explain what is going on or what I am doing wrong?
>
>
> Third question: I extrapolate that merge() expects *all* fields are
> populated? In other words, if merge() encounters a field whose value
> is None, will it update that field to null in the database (as opposed
> to leaving the value untouched in the database)? Does None mean
> "leave it alone" or "update to null"?
>
>
>
>
> full output pasted here:
> ===========
> 2010-01-14 02:45:16,296 INFO sqlalchemy.engine.base.Engine.0x...4e50
> BEGIN
> 2010-01-14 02:45:16,296 INFO sqlalchemy.engine.base.Engine.0x...4e50
> SELECT orders.id AS orders_id, orders.customer AS orders_customer
> FROM orders
> WHERE orders.id = :param_1
> 2010-01-14 02:45:16,296 INFO sqlalchemy.engine.base.Engine.0x...4e50
> {'param_1': '55'}
> 2010-01-14 02:45:16,298 INFO sqlalchemy.engine.base.Engine.0x...4e50
> SELECT orderdetails.orderid AS orderdetails_orderid, orderdetails.line
> AS orderdetails_line, orderdetails.product AS orderdetails_product,
> orderdetails.qtyordered AS orderdetails_qtyordered
> FROM orderdetails
> WHERE orderdetails.orderid = :param_1 AND orderdetails.line = :param_2
> 2010-01-14 02:45:16,298 INFO sqlalchemy.engine.base.Engine.0x...4e50
> {'param_1': '55', 'param_2': 2}
> 2010-01-14 02:45:16,302 INFO sqlalchemy.engine.base.Engine.0x...4e50
> SELECT orderdetails.orderid AS orderdetails_orderid, orderdetails.line
> AS orderdetails_line, orderdetails.product AS orderdetails_product,
> orderdetails.qtyordered AS orderdetails_qtyordered
> FROM orderdetails
> WHERE orderdetails.orderid = :param_1 AND orderdetails.line = :param_2
> 2010-01-14 02:45:16,302 INFO sqlalchemy.engine.base.Engine.0x...4e50
> {'param_1': '55', 'param_2': 3}
> 2010-01-14 02:45:16,305 INFO sqlalchemy.engine.base.Engine.0x...4e50
> SELECT orderdetails.qtyordered AS orderdetails_qtyordered
> FROM orderdetails
> WHERE orderdetails.orderid = :param_1 AND orderdetails.line = :param_2
> 2010-01-14 02:45:16,305 INFO sqlalchemy.engine.base.Engine.0x...4e50
> {'param_1': '55', 'param_2': 3}
> /home/rarch/tg2env/lib/python2.6/site-packages/SQLAlchemy-0.5.2-
> py2.6.egg/sqlalchemy/engine/default.py:241: SAWarning: Unicode type
> received non-unicode bind param value 'CHAIR'
> param[key.encode(encoding)] = processors[key](compiled_params[key])
> 2010-01-14 02:45:16,306 INFO sqlalchemy.engine.base.Engine.0x...4e50
> INSERT INTO orderdetails (orderid, line, product, qtyordered) VALUES
> (:orderid, :line, :product, :qtyordered)
> 2010-01-14 02:45:16,307 INFO sqlalchemy.engine.base.Engine.0x...4e50
> {'orderid': '55', 'line': 3, 'product': 'CHAIR', 'qtyordered': None}
> 2010-01-14 02:45:16,308 INFO sqlalchemy.engine.base.Engine.0x...4e50
> SELECT orderdetails.orderid AS orderdetails_orderid, orderdetails.line
> AS orderdetails_line, orderdetails.product AS orderdetails_product,
> orderdetails.qtyordered AS orderdetails_qtyordered
> FROM orderdetails
> WHERE :param_1 = orderdetails.orderid
> 2010-01-14 02:45:16,308 INFO sqlalchemy.engine.base.Engine.0x...4e50
> {'param_1': '55'}
>>>>
>>>>
>>>>
>>>> session.commit()
> 2010-01-14 02:45:30,143 INFO sqlalchemy.engine.base.Engine.0x...4e50
> ROLLBACK
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/session.py", line 673, in
> commit
> self.transaction.commit()
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/session.py", line 378, in
> commit
> self._prepare_impl()
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/session.py", line 362, in
> _prepare_impl
> self.session.flush()
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/session.py", line 1347, in
> flush
> self._flush(objects)
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/session.py", line 1417, in
> _flush
> flush_context.execute()
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/unitofwork.py", line 244, in
> execute
> UOWExecutor().execute(self, tasks)
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/unitofwork.py", line 707, in
> execute
> self.execute_save_steps(trans, task)
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/unitofwork.py", line 724, in
> execute_save_steps
> self.execute_dependencies(trans, task)
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/unitofwork.py", line 733, in
> execute_dependencies
> self.execute_dependency(trans, dep, False)
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/unitofwork.py", line 719, in
> execute_dependency
> dep.execute(trans, isdelete)
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/unitofwork.py", line 686, in
> execute
> delete=delete)
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/dependency.py", line 353, in
> process_dependencies
> self._synchronize(state, child, None, False, uowcommit)
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/dependency.py", line 395, in
> _synchronize
> sync.clear(state, self.parent, self.prop.synchronize_pairs)
> File "/home/rarch/tg2env/lib/python2.6/site-packages/
> SQLAlchemy-0.5.2-py2.6.egg/sqlalchemy/orm/sync.py", line 28, in clear
> raise AssertionError("Dependency rule tried to blank-out primary
> key column '%s' on instance '%s'" % (r, mapperutil.state_str(dest)))
> AssertionError: Dependency rule tried to blank-out primary key column
> 'orderdetails.orderid' on instance '<OrderDetail at 0x2cc5850>'
>
>
>
>
>
>
>
>
>
>
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