On 02/23/2016 10:47 AM, Piotr Dobrogost wrote:
Hi!
I'm getting AssertionError: Dependency rule tried to blank-out primary
key column 'text_value.text_id' on instance '<TextValue at
0x7f6b260d9710>' error while trying to update row using association
proxy ('values') like this:
|
session.add(Text(values={'pl':u'org','en':u'org'}))
text =session.query(Text).one()
text.values ={'pl':u'modified','en':u'modified'}
session.commit()
|
Working example is at
https://gist.github.com/piotr-dobrogost/74073cf11006fb68e555
What am I doing wrong?
well the first thing is you definitely don't need
UniqueConstraint('lang_id', 'text_id') because these columns are already
in the primary key.
the next issue in this test at least is that you're referring to the
primary key of a row in Lang but there is no Lang row being created
here. SQLite will let you put the invalid primary key into lang_id but
only because foreign keys aren't enforced by default.
then the reason for the error is that TextValue objects are potentially
being replaced but the mapping is not emitting a delete for the old
TextValue, so you'd need to put cascade="all, delete-orphan" on the
Text._values relationship so that when you assign a new dictionary
value, the old TextValue objects are deleted.
In this specific example, marking the TextValue as deleted ends up gving
you an UPDATE of TextValue, because the ORM converts an INSERT/DELETE of
the same primary key into a single UPDATE. But if your dictionary
removed some of those keys you'd need a DELETE so the cascade rule
should be applied here.
Best regards,
Piotr Dobrogost
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