This is why they are getting inserted again:
Well, logging out
"currentUser.editingContext().committedSnapshotForObject(currentUser)['userDataBlock']"
before saveChanges, I get an empty array. I must admit I don't know whether
there should be the relationship objects in this snapshot, but anyway:
It should not be an empty array. EOF compares this and the relationship on the
EO to determine what database operations are needed. I’d start with logging
that out just after you fetch/fault currentUser into ec (you don’t show that
below). If it is empty there, then keep logging to see where the data
disappears. At this point, I am not ready to guess.
Also, this is 100% consistent, right? This is not a concurrency issue?
Chuck
From: <webobjects-dev-bounces+chill=gevityinc....@lists.apple.com> on behalf of
"o...@ocs.cz" <o...@ocs.cz>
Date: Tuesday, September 20, 2016 at 11:50 AM
To: "webobjects-dev@lists.apple.com WebObjects" <webobjects-dev@lists.apple.com>
Subject: EOF inserts already existing M:N relationships/empty snapshot?!?
Hello there,
I have a pretty common setup: entities User and DataBlock, an M:N relationship
represented by an intermediate entity containing just the two keys, flattened
on both sides. At both sides the relationships are appropriately flattened. Set
to own destination+delete rule cascade.
The problem is, upon inserting a new DataBlock and its relationship to a
current user, beside the two objects which should be inserted (the new
DataBlock and the new relationship), relationships to other (old) DataBlocks,
which were before simply _fetched_ for the current user (just to display the
current state), get inserted too — which, of course, causes an integrity
constraint violation “this PK already exists“.
My code looks essentially like this:
===
EOEditingContext ec= ...
DBDataBlock ndb=new DBDataBlock()
ec.insertObject(ndb)
ndb.addObjectToBothSidesOfRelationshipWithKey(currentUser,'dataBlockUsers')
// logs here, see below
ec.saveChanges()
===
Immediately before ec.saveChanges(), I log out
(a) ec.insertedObjects(), which contains only one object (I have overridden
toString() to get the PK /and other attributes, removed here for conciseness/
of an EO):
[<DBDataBlock@79adaefa PK:null>]
this is all right, null PK means a newly added object, it's the very 'ndb'
datablock I just have inserted and which I am now saving.
(b) contents of the flattened M:N relationship 'ndb.dataBlockUsers' from the
DBDataBlock@79adaefa to DBUser, which looks like this:
[<DBUser@71b29988 PK:1000005>]
again, quite all right: only one related user, the currentUser which I have
just added to the relationship.
(c) contents of the flattened M:N inverse relationship from the current user,
which looks like this:
[<DBDataBlock@189f083a PK:1000003>, <DBDataBlock@1b47d247 PK:1000016>,
<DBDataBlock@5f927095 PK:1000019>, <DBDataBlock@54edfe4c PK:1000022>,
<DBDataBlock@35e1e59c PK:1000023>, <DBDataBlock@793b3d6d PK:1000024>,
<DBDataBlock@7b06dee8 PK:1000029>, <DBDataBlock@2550aab9 PK:1000033>,
<DBDataBlock@79adaefa PK:null>]
for the third time, all right: 8 of them previously fetched, already existing
relationships to other (old) datablocks for the current user, plus one new
relationship to the newly added DBDataBlock@79adaefa. Perfect so far.
At this moment, ec.saveChanges is performed. I log the database operations from
databaseContextWillPerformAdaptorOperations delegate method, and it looks like
this:
===
-IN-adaptorOps === SPC: about to perform 10 DB operations |19:54:37.061
20.9.16|WorkerThread1
- 1: INSERT on 'DBDataBlock' 1{uid:1000042}
- 2: INSERT on 'DB_UserDataBlock' 2{db_id:1000023,
user_id:1000005}
- 3: INSERT on 'DB_UserDataBlock' 2{db_id:1000022,
user_id:1000005}
- 4: INSERT on 'DB_UserDataBlock' 2{db_id:1000003,
user_id:1000005}
- 5: INSERT on 'DB_UserDataBlock' 2{db_id:1000016,
user_id:1000005}
- 6: INSERT on 'DB_UserDataBlock' 2{db_id:1000042,
user_id:1000005}
- 7: INSERT on 'DB_UserDataBlock' 2{db_id:1000019,
user_id:1000005}
- 8: INSERT on 'DB_UserDataBlock' 2{db_id:1000029,
user_id:1000005}
- 9: INSERT on 'DB_UserDataBlock' 2{db_id:1000024,
user_id:1000005}
- 10: INSERT on 'DB_UserDataBlock' 2{db_id:1000033,
user_id:1000005}
===
i.e., along with inserting the two new objects (1: the new datablock, 6: the
new relationship), EOF for some darned reason decides to insert _also_ all
those relationship objects it _fetched_ before! Of course, since they were
fetched, they already exist in the database, and thus cause an integrity
constraint violation “this PK already exists“.
Well, logging out
"currentUser.editingContext().committedSnapshotForObject(currentUser)['userDataBlock']"
before saveChanges, I get an empty array. I must admit I don't know whether
there should be the relationship objects in this snapshot, but anyway:
- if not, I have no idea where to find the culprit;
- if yes, well, the culprit of those inserts is explained, but why on earth the
snapshot is not properly maintained by EOF?!?
Any idea what might be the culprit, or at least, how to find it? I am afraid I
am rather out of ideas :/
Thanks a lot,
OC
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