[sqlalchemy] Re: Polymorphic union of two sibling classes (no real inheritance)
Hopefully you've got time to read a compliment: this polymorphism is
very cool (well, sqla in general). Great work!
Kent
On Jul 29, 5:41 pm, Michael Bayer mike...@zzzcomputing.com wrote:
On Jul 29, 2010, at 5:00 PM, Kent Bower wrote:
Right. I understand. Thanks for pointing that out, you are correct.
My bigger concern was getting the ArTranBase mapper correct. Apparently
there is no need in this case to specify with_polymorphic= in the mapper.
Did I miss documentation on using 'polymorphic_union' without
with_polymorphic=? That seems to be working, I was just looking for
confirmation that this is a supported use-case.
that is probably correct.
On 7/29/2010 4:51 PM, Michael Bayer wrote:
What I meant was, if you want to say session.query(ArTranBase), which it
appears that you do, then you are querying against ArTranBase.
Since it seems like you want the polymorphic_union here, when you query
ArTranBase and you want it to eagerly load trancode and paymenttype,
it would need to have a relation() on the ArTranBase mapper so that it
knows what to join.
On Jul 29, 2010, at 4:46 PM, Kent wrote:
This seems to work, but I didn't find examples of this. Does this
look correct (assuming there is no parent table in the database and
all I really want is 2 'normal' mappers and a 3rd that performs a
polymorphoric_union)?
==
artran_union = polymorphic_union({
'artran': artrans_table,
'archive': artransarchive_table
}, 'type', 'artran_union')
artranbase_mapper = mapper(ArTranBase, artran_union,
polymorphic_on=artran_union.c.type)
# ArTran
--- #
mapper(ArTran, artrans_table, inherits=artranbase_mapper,
concrete=True, polymorphic_identity='artran',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTranArchive
--- #
mapper(ArTranArchive, artransarchive_table,
inherits=artranbase_mapper,
concrete=True, polymorphic_identity='archive',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
On Jul 29, 4:20 pm, Kent Bowerk...@retailarchitects.com wrote:
No, in fact, there is no ArTranBase table at all.
If I remove concrete inheritance, how do I issue a UNION of the two
tables and have the objects polymorphically loaded?
On 7/29/2010 4:18 PM, Michael Bayer wrote:
On Jul 29, 2010, at 2:31 PM, Kent wrote:
I'm getting a messy error that could be a bug, but is very likely
related to my setup of a set of 2 polymorphic classes I am attempting
to map.
One entity is a transaction and the other is a transaction_archive
record. The table structure is therefore very similar for both tables
and it seems to fit Concrete Table Inheritance, except there is no
'parent' entity. Rather, they are sister tables.
What I have mostly works until I get into loading this union as a
relation to another table... then I'm having problems.
I couldn't clearly see the correct way to set up this when there is
no real inheritance, but rather sister entities.
Can you suggest how to correctly map these 2 tables?
it looks fine to me except you're asking for eager loading, and if
you're querying from the ArTranBase you'd need to specify
relationship() at that level (as well as on each child). Example
athttp://www.sqlalchemy.org/docs/mappers.html#using-relationships-with-
OTOH if you are not querying from ArTranBase, remove the usage of
concrete inheritance altogether.
artran_union = polymorphic_union({
'artran': artrans_table,
'archive': artransarchive_table
}, 'type', 'artran_union')
artranbase_mapper = mapper(ArTranBase, artran_union,
with_polymorphic=('*', artran_union),
polymorphic_on=artran_union.c.type,
polymorphic_identity='ignored')
# ArTran
--- #
mapper(ArTran, artrans_table, inherits=artranbase_mapper,
concrete=True, polymorphic_identity='artran',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTranArchive
--- #
mapper(ArTranArchive, artransarchive_table,
[sqlalchemy] Re: Polymorphic union of two sibling classes (no real inheritance)
I am having a problem when I'm specifying an order_by for a
relationship entity's column when the relationship is this
polymorphic_union.
orders = DBSession.query(Order)\
.options(joinedload(Order.transactions))\
.filter(Order.customerid==customerid)\
.order_by(Order.orderdate, desc(ArTranBase.postdate)).all()
The SQL output is like this:
#
SELECT * ...
FROM orders,
orderdetails orderdetails_1,
...
...,
/ polymorphic union (labeled 'anon_1') /
(SELECT artrans.orderid AS orderid,
artrans.status AS status,
...
'artran' AS type
FROM artrans
UNION ALL
SELECT artransarchive.orderid AS orderid,
artransarchive.status AS status,
...
'archive' AS type
FROM artransarchive) anon_1,
paymenttypes paymenttypes_1,
...
WHERE ... /* joins */
AND orders.orderid = anon_1.orderid(+)
... /* more joins */
ORDER BY orders.orderdate,
artran_union.postdate DESC
#
*Notice the Problem:
The ORDER BY is specifying the column 'artran_union.postdate' instead
of 'anon_1.postdate'. The joins are correctly using 'anon_1'.
(or, perhaps the union itself should be labeled 'artran_union' or
'artran_union_1').
Mapping info:
# Order
order_mapper = mapper(Order, orders_table,
properties={
...
...
'transactions': relation(ArTranBase,
cascade='refresh-expire,expunge')
})
artran_union = polymorphic_union({
'artran': artrans_table,
'archive': artransarchive_table
}, 'type', 'artran_union')
# ArTranBase
artranbase_mapper = mapper(ArTranBase, artran_union,
polymorphic_on=artran_union.c.type,
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTran
mapper(ArTran, artrans_table, inherits=artranbase_mapper,
concrete=True, polymorphic_identity='artran',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTranArchive
mapper(ArTranArchive, artransarchive_table,
inherits=artranbase_mapper,
concrete=True, polymorphic_identity='archive',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
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Re: [sqlalchemy] Re: Polymorphic union of two sibling classes (no real inheritance)
On Jul 30, 2010, at 9:51 AM, Kent wrote:
I am having a problem when I'm specifying an order_by for a
relationship entity's column when the relationship is this
polymorphic_union.
orders = DBSession.query(Order)\
.options(joinedload(Order.transactions))\
.filter(Order.customerid==customerid)\
.order_by(Order.orderdate, desc(ArTranBase.postdate)).all()
you're making a common mistake here which is to ORDER BY an eagerly loaded
relationship (probably our first FAQ entry).joinedload is strictly about
loading collection contents and will alias itself so as not to interfere with
the query's existing structure. Here you'd want to
query(Order).join(Order.transactions).options(contains_eager(Order.transactions)).order_by(...).
But the awkwardness here is that if Order.transactions is a collection, the
order_by() you're doing doesn't make much sense - if Order 1 and Order 2 have
the same date, but their collection of transactions are interleaved in terms of
their dates, the ordering between them is somewhat meaningless.
If the order_by() is instead intended to determine the ordering just *within*
the Order.transactions collections, you'd use the order_by option on the
transactions relationship() itself.
The SQL output is like this:
#
SELECT * ...
FROM orders,
orderdetails orderdetails_1,
...
...,
/ polymorphic union (labeled 'anon_1') /
(SELECT artrans.orderid AS orderid,
artrans.status AS status,
...
'artran' AS type
FROM artrans
UNION ALL
SELECT artransarchive.orderid AS orderid,
artransarchive.status AS status,
...
'archive' AS type
FROM artransarchive) anon_1,
paymenttypes paymenttypes_1,
...
WHERE ... /* joins */
AND orders.orderid = anon_1.orderid(+)
... /* more joins */
ORDER BY orders.orderdate,
artran_union.postdate DESC
#
*Notice the Problem:
The ORDER BY is specifying the column 'artran_union.postdate' instead
of 'anon_1.postdate'. The joins are correctly using 'anon_1'.
(or, perhaps the union itself should be labeled 'artran_union' or
'artran_union_1').
Mapping info:
# Order
order_mapper = mapper(Order, orders_table,
properties={
...
...
'transactions': relation(ArTranBase,
cascade='refresh-expire,expunge')
})
artran_union = polymorphic_union({
'artran': artrans_table,
'archive': artransarchive_table
}, 'type', 'artran_union')
# ArTranBase
artranbase_mapper = mapper(ArTranBase, artran_union,
polymorphic_on=artran_union.c.type,
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTran
mapper(ArTran, artrans_table, inherits=artranbase_mapper,
concrete=True, polymorphic_identity='artran',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTranArchive
mapper(ArTranArchive, artransarchive_table,
inherits=artranbase_mapper,
concrete=True, polymorphic_identity='archive',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
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[sqlalchemy] Re: Polymorphic union of two sibling classes (no real inheritance)
This seems to work, but I didn't find examples of this. Does this
look correct (assuming there is no parent table in the database and
all I really want is 2 'normal' mappers and a 3rd that performs a
polymorphoric_union)?
==
artran_union = polymorphic_union({
'artran': artrans_table,
'archive': artransarchive_table
}, 'type', 'artran_union')
artranbase_mapper = mapper(ArTranBase, artran_union,
polymorphic_on=artran_union.c.type)
# ArTran
--- #
mapper(ArTran, artrans_table, inherits=artranbase_mapper,
concrete=True, polymorphic_identity='artran',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTranArchive
--- #
mapper(ArTranArchive, artransarchive_table,
inherits=artranbase_mapper,
concrete=True, polymorphic_identity='archive',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
On Jul 29, 4:20 pm, Kent Bower k...@retailarchitects.com wrote:
No, in fact, there is no ArTranBase table at all.
If I remove concrete inheritance, how do I issue a UNION of the two
tables and have the objects polymorphically loaded?
On 7/29/2010 4:18 PM, Michael Bayer wrote:
On Jul 29, 2010, at 2:31 PM, Kent wrote:
I'm getting a messy error that could be a bug, but is very likely
related to my setup of a set of 2 polymorphic classes I am attempting
to map.
One entity is a transaction and the other is a transaction_archive
record. The table structure is therefore very similar for both tables
and it seems to fit Concrete Table Inheritance, except there is no
'parent' entity. Rather, they are sister tables.
What I have mostly works until I get into loading this union as a
relation to another table... then I'm having problems.
I couldn't clearly see the correct way to set up this when there is
no real inheritance, but rather sister entities.
Can you suggest how to correctly map these 2 tables?
it looks fine to me except you're asking for eager loading, and if you're
querying from the ArTranBase you'd need to specify relationship() at that
level (as well as on each child). Example
athttp://www.sqlalchemy.org/docs/mappers.html#using-relationships-with-
OTOH if you are not querying from ArTranBase, remove the usage of concrete
inheritance altogether.
artran_union = polymorphic_union({
'artran': artrans_table,
'archive': artransarchive_table
}, 'type', 'artran_union')
artranbase_mapper = mapper(ArTranBase, artran_union,
with_polymorphic=('*', artran_union),
polymorphic_on=artran_union.c.type,
polymorphic_identity='ignored')
# ArTran
--- #
mapper(ArTran, artrans_table, inherits=artranbase_mapper,
concrete=True, polymorphic_identity='artran',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTranArchive
--- #
mapper(ArTranArchive, artransarchive_table,
inherits=artranbase_mapper,
concrete=True, polymorphic_identity='archive',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
Thanks in advance.
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Re: [sqlalchemy] Re: Polymorphic union of two sibling classes (no real inheritance)
What I meant was, if you want to say session.query(ArTranBase), which it
appears that you do, then you are querying against ArTranBase.
Since it seems like you want the polymorphic_union here, when you query
ArTranBase and you want it to eagerly load trancode and paymenttype, it
would need to have a relation() on the ArTranBase mapper so that it knows what
to join.
On Jul 29, 2010, at 4:46 PM, Kent wrote:
This seems to work, but I didn't find examples of this. Does this
look correct (assuming there is no parent table in the database and
all I really want is 2 'normal' mappers and a 3rd that performs a
polymorphoric_union)?
==
artran_union = polymorphic_union({
'artran': artrans_table,
'archive': artransarchive_table
}, 'type', 'artran_union')
artranbase_mapper = mapper(ArTranBase, artran_union,
polymorphic_on=artran_union.c.type)
# ArTran
--- #
mapper(ArTran, artrans_table, inherits=artranbase_mapper,
concrete=True, polymorphic_identity='artran',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTranArchive
--- #
mapper(ArTranArchive, artransarchive_table,
inherits=artranbase_mapper,
concrete=True, polymorphic_identity='archive',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
On Jul 29, 4:20 pm, Kent Bower k...@retailarchitects.com wrote:
No, in fact, there is no ArTranBase table at all.
If I remove concrete inheritance, how do I issue a UNION of the two
tables and have the objects polymorphically loaded?
On 7/29/2010 4:18 PM, Michael Bayer wrote:
On Jul 29, 2010, at 2:31 PM, Kent wrote:
I'm getting a messy error that could be a bug, but is very likely
related to my setup of a set of 2 polymorphic classes I am attempting
to map.
One entity is a transaction and the other is a transaction_archive
record. The table structure is therefore very similar for both tables
and it seems to fit Concrete Table Inheritance, except there is no
'parent' entity. Rather, they are sister tables.
What I have mostly works until I get into loading this union as a
relation to another table... then I'm having problems.
I couldn't clearly see the correct way to set up this when there is
no real inheritance, but rather sister entities.
Can you suggest how to correctly map these 2 tables?
it looks fine to me except you're asking for eager loading, and if you're
querying from the ArTranBase you'd need to specify relationship() at that
level (as well as on each child). Example
athttp://www.sqlalchemy.org/docs/mappers.html#using-relationships-with-
OTOH if you are not querying from ArTranBase, remove the usage of concrete
inheritance altogether.
artran_union = polymorphic_union({
'artran': artrans_table,
'archive': artransarchive_table
}, 'type', 'artran_union')
artranbase_mapper = mapper(ArTranBase, artran_union,
with_polymorphic=('*', artran_union),
polymorphic_on=artran_union.c.type,
polymorphic_identity='ignored')
# ArTran
--- #
mapper(ArTran, artrans_table, inherits=artranbase_mapper,
concrete=True, polymorphic_identity='artran',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTranArchive
--- #
mapper(ArTranArchive, artransarchive_table,
inherits=artranbase_mapper,
concrete=True, polymorphic_identity='archive',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
Thanks in advance.
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To
Re: [sqlalchemy] Re: Polymorphic union of two sibling classes (no real inheritance)
Right. I understand. Thanks for pointing that out, you are correct.
My bigger concern was getting the ArTranBase mapper correct. Apparently
there is no need in this case to specify with_polymorphic= in the
mapper. Did I miss documentation on using 'polymorphic_union' without
with_polymorphic=? That seems to be working, I was just looking for
confirmation that this is a supported use-case.
On 7/29/2010 4:51 PM, Michael Bayer wrote:
What I meant was, if you want to say session.query(ArTranBase), which it
appears that you do, then you are querying against ArTranBase.
Since it seems like you want the polymorphic_union here, when you query ArTranBase and you want it
to eagerly load trancode and paymenttype, it would need to have a
relation() on the ArTranBase mapper so that it knows what to join.
On Jul 29, 2010, at 4:46 PM, Kent wrote:
This seems to work, but I didn't find examples of this. Does this
look correct (assuming there is no parent table in the database and
all I really want is 2 'normal' mappers and a 3rd that performs a
polymorphoric_union)?
==
artran_union = polymorphic_union({
'artran': artrans_table,
'archive': artransarchive_table
}, 'type', 'artran_union')
artranbase_mapper = mapper(ArTranBase, artran_union,
polymorphic_on=artran_union.c.type)
# ArTran
--- #
mapper(ArTran, artrans_table, inherits=artranbase_mapper,
concrete=True, polymorphic_identity='artran',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTranArchive
--- #
mapper(ArTranArchive, artransarchive_table,
inherits=artranbase_mapper,
concrete=True, polymorphic_identity='archive',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
On Jul 29, 4:20 pm, Kent Bowerk...@retailarchitects.com wrote:
No, in fact, there is no ArTranBase table at all.
If I remove concrete inheritance, how do I issue a UNION of the two
tables and have the objects polymorphically loaded?
On 7/29/2010 4:18 PM, Michael Bayer wrote:
On Jul 29, 2010, at 2:31 PM, Kent wrote:
I'm getting a messy error that could be a bug, but is very likely
related to my setup of a set of 2 polymorphic classes I am attempting
to map.
One entity is a transaction and the other is a transaction_archive
record. The table structure is therefore very similar for both tables
and it seems to fit Concrete Table Inheritance, except there is no
'parent' entity. Rather, they are sister tables.
What I have mostly works until I get into loading this union as a
relation to another table... then I'm having problems.
I couldn't clearly see the correct way to set up this when there is
no real inheritance, but rather sister entities.
Can you suggest how to correctly map these 2 tables?
it looks fine to me except you're asking for eager loading, and if you're
querying from the ArTranBase you'd need to specify relationship() at that level
(as well as on each child). Example
athttp://www.sqlalchemy.org/docs/mappers.html#using-relationships-with-
OTOH if you are not querying from ArTranBase, remove the usage of concrete
inheritance altogether.
artran_union = polymorphic_union({
'artran': artrans_table,
'archive': artransarchive_table
}, 'type', 'artran_union')
artranbase_mapper = mapper(ArTranBase, artran_union,
with_polymorphic=('*', artran_union),
polymorphic_on=artran_union.c.type,
polymorphic_identity='ignored')
# ArTran
--- #
mapper(ArTran, artrans_table, inherits=artranbase_mapper,
concrete=True, polymorphic_identity='artran',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTranArchive
--- #
mapper(ArTranArchive, artransarchive_table,
inherits=artranbase_mapper,
concrete=True, polymorphic_identity='archive',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
Re: [sqlalchemy] Re: Polymorphic union of two sibling classes (no real inheritance)
On Jul 29, 2010, at 5:00 PM, Kent Bower wrote:
Right. I understand. Thanks for pointing that out, you are correct.
My bigger concern was getting the ArTranBase mapper correct. Apparently
there is no need in this case to specify with_polymorphic= in the mapper.
Did I miss documentation on using 'polymorphic_union' without
with_polymorphic=? That seems to be working, I was just looking for
confirmation that this is a supported use-case.
that is probably correct.
On 7/29/2010 4:51 PM, Michael Bayer wrote:
What I meant was, if you want to say session.query(ArTranBase), which it
appears that you do, then you are querying against ArTranBase.
Since it seems like you want the polymorphic_union here, when you query
ArTranBase and you want it to eagerly load trancode and paymenttype, it
would need to have a relation() on the ArTranBase mapper so that it knows
what to join.
On Jul 29, 2010, at 4:46 PM, Kent wrote:
This seems to work, but I didn't find examples of this. Does this
look correct (assuming there is no parent table in the database and
all I really want is 2 'normal' mappers and a 3rd that performs a
polymorphoric_union)?
==
artran_union = polymorphic_union({
'artran': artrans_table,
'archive': artransarchive_table
}, 'type', 'artran_union')
artranbase_mapper = mapper(ArTranBase, artran_union,
polymorphic_on=artran_union.c.type)
# ArTran
--- #
mapper(ArTran, artrans_table, inherits=artranbase_mapper,
concrete=True, polymorphic_identity='artran',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTranArchive
--- #
mapper(ArTranArchive, artransarchive_table,
inherits=artranbase_mapper,
concrete=True, polymorphic_identity='archive',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
On Jul 29, 4:20 pm, Kent Bowerk...@retailarchitects.com wrote:
No, in fact, there is no ArTranBase table at all.
If I remove concrete inheritance, how do I issue a UNION of the two
tables and have the objects polymorphically loaded?
On 7/29/2010 4:18 PM, Michael Bayer wrote:
On Jul 29, 2010, at 2:31 PM, Kent wrote:
I'm getting a messy error that could be a bug, but is very likely
related to my setup of a set of 2 polymorphic classes I am attempting
to map.
One entity is a transaction and the other is a transaction_archive
record. The table structure is therefore very similar for both tables
and it seems to fit Concrete Table Inheritance, except there is no
'parent' entity. Rather, they are sister tables.
What I have mostly works until I get into loading this union as a
relation to another table... then I'm having problems.
I couldn't clearly see the correct way to set up this when there is
no real inheritance, but rather sister entities.
Can you suggest how to correctly map these 2 tables?
it looks fine to me except you're asking for eager loading, and if you're
querying from the ArTranBase you'd need to specify relationship() at that
level (as well as on each child). Example
athttp://www.sqlalchemy.org/docs/mappers.html#using-relationships-with-
OTOH if you are not querying from ArTranBase, remove the usage of
concrete inheritance altogether.
artran_union = polymorphic_union({
'artran': artrans_table,
'archive': artransarchive_table
}, 'type', 'artran_union')
artranbase_mapper = mapper(ArTranBase, artran_union,
with_polymorphic=('*', artran_union),
polymorphic_on=artran_union.c.type,
polymorphic_identity='ignored')
# ArTran
--- #
mapper(ArTran, artrans_table, inherits=artranbase_mapper,
concrete=True, polymorphic_identity='artran',
properties={'trancode': relation(TranCode,
cascade='refresh-expire,expunge', lazy=False),
'paymenttype': relation(PaymentType,
cascade='refresh-expire,expunge', lazy=False)}
)
# ArTranArchive
--- #
mapper(ArTranArchive, artransarchive_table,
inherits=artranbase_mapper,
concrete=True,
