I just committed revision 800 which makes the correct adjustment to
properly add reflected foreign keys. However, as of yet i have not
figured out a way to get the foreign keys back when using MySQL and I
suspect there may not be one (table reflection is still only mysql5
compatible also...anyone want to give me a freebie on mysql3/4 ?
oracle ? ) .
So while sqlite and postgres (and someday oracle, when i write
reflection for it) should find their own foreign keys and allow your
example to work, with mysql you need to add them explictly. I added
an "append_item()" method to Column and made it so that code which
explicitly adds foreign keys will cleanly replace any that that were
automatically reflected so you can safely make them explicit in order
to write database-neutral code, i.e.
# fine for sqlite/postgres, wont work in mysql
master = Table( "MASTER", engine, autoload=True)
detail = Table("DETAIL", engine, autoload=True)
j = join(master, detail)
print str(j.onclause)
# fine for sqlite/postgres/mysql
master = Table( "MASTER", engine, autoload=True)
detail = Table("DETAIL", engine, autoload=True)
detail.c.master_id.append_item(ForeignKey("master.master_id"))
j = join(master, detail)
print str(j.onclause)
On Jan 8, 2006, at 10:15 AM, Murat Özsöyler wrote:
Hi,
When autoloading table metadata from sqlite database, I have
confronted an error. Foreign key definition for column is not
reflected in table's foreign_keys property, foreign_key property of
the related contains a ForeignKey class reference though. This
causes errors when creating associated mapper which also creates
one to many relation regarding the problem ForeignKey. If one
appends column.foreign key to the table.foreign_keys, mapper can be
created as in the example below.
from sqlalchemy import *
engine = create_engine("sqlite://filename=trial.db")
master = Table( "MASTER", engine, autoload=True)
detail = Table("DETAIL", engine, autoload=True)
# DETAIL table contains a column definition like this:
# MASTER_ID integer references MASTER(ID),
class Master(object):
pass
class Detail(object):
pass
detail.foreign_keys.append(detail.c.MASTER_ID.foreign_key)
# below command gives error
# "Cant find any foreign key relationships between 'MASTER'
# (<sqlalchemy.schema.Table object at 0x01FDBE30>) and 'DETAIL'
# (<sqlalchemy.schema.Table object at 0x01FDBED0>)" if the line
# above is commented
# on the other hand gives
# "AttributeError: parent" if uncommented.
#
# If all is entered from the intepreter, the line below gives no
# error if the command above is uncommented but the details property
# is not created
#
Master.mapper = mapper(Master, master, properties={
"details": relation(Detail, detail)
}
)
Am I doing something wrong?
Regards,
Murat Ozsoyler
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