Pavel Dyadych created CAY-1710:
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Summary: Change default delete rule for runtime relationship
Key: CAY-1710
URL: https://issues.apache.org/jira/browse/CAY-1710
Project: Cayenne
Issue Type: Improvement
Components: Core Library
Reporter: Pavel Dyadych
It should be good to change default delete rule of runtime relationship from
NO_ACTION to NULLIFY. It will protect us from bogus references in dependent
objects without reverse relationships.
Suppose we have such model:
* ARTIST(ID, NAME) ==> Artist(name, paintings)
* PAINTING(ID, NAME, ARTIST_ID, GALLERY_ID) ==> Painting(name, artist) // no
reverse to Gallery
* GALLERY(ID, NAME) ==> Gallery(name, paintings)
Delete rule of relationship Artist-toMany-Paintings is set to CASCADE. Expect
that after deleting Artist corresponding Paintings will be deleted too.. and
also deleted from galleries thanks to reverse runtime relationship
Painting-toOne-Gallery created by Cayenne.
After adding data to database (print result of SelectQuery):
* Artists: Picasso
* Paintings: "Girl Reading at a Table" by Picasso
* Galleries: Metropolitan Museum of Art: ["Girl Reading at a Table" by Picasso]
After deleting object Picasso (print result of SelectQuery):
* Artists:
* Paintings:
* Galleries: Metropolitan Museum of Art: ["Girl Reading at a Table" by null] //
that is BIZARRE!
This happens because when cascading delete comes to painting Girl it detects
relationship with delete rule NO_ACTION. And so gallery stays with bogus
reference.
PS. After recreation of ObjectContext all bogus objects of course dissapear
because they do not exist in database.
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