#28408: Inconsistant error message for trying to update an annotated F
expression
-------------------------------------+-------------------------------------
Reporter: Kevin | Owner: (none)
Marsh |
Type: | Status: new
Uncategorized |
Component: Error | Version: 1.11
reporting |
Severity: Normal | Keywords: annotate, F, update
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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I ran into a bit of a nasty error yesterday on Django 1.11, Postgres 9.5
where I was trying to do an update using an `F` expression where the value
in that expression referred to an annotation of an annotation, each using
a `Case` statement inside the annotation. The error message it was giving
me was something like the following:
{{{
ProgrammingError Traceback (most recent call
last)
<ipython-input-1-29e48364245c> in <module>()
----> 1 MyModel.objects.causing_problems()
/usr/src/app/apps/myapp/managers.py in causing_problems(self)
833 ).update(
--> 834 my_field=F('my_annotated_field'),
835 )
836
/usr/src/app/apps/django/db/models/query.py in update(self, **kwargs)
645 query._annotations = None
646 with transaction.atomic(using=self.db, savepoint=False):
--> 647 rows = query.get_compiler(self.db).execute_sql(CURSOR)
648 self._result_cache = None
649 return rows
/usr/src/app/apps/django/db/models/sql/compiler.py in execute_sql(self,
result_type)
1189 related queries are not available.
1190 """
-> 1191 cursor = super(SQLUpdateCompiler,
self).execute_sql(result_type)
1192 try:
1193 rows = cursor.rowcount if cursor else 0
/usr/src/app/apps/django/db/models/sql/compiler.py in execute_sql(self,
result_type, chunked_fetch)
884 # silencing when dropping Python 2 compatibility.
885 pass
--> 886 raise original_exception
887
888 if result_type == CURSOR:
ProgrammingError: missing FROM-clause entry for table "myapp_mymodel"
LINE 1: ...false END, "a_field" = CASE WHEN CASE WHEN ("myapp_my...
}}}
Spent a while trying to debug where it was going wrong, ended up narrowing
down the problem to trying to update a field using an `F` expression on an
annotated field which included a join in it. I'm not sure if better error
message would have helped in my case but in the much simpler test attached
it'd be usfeul if the first and second assertions raised the same or
similar error message.
--
Ticket URL: <https://code.djangoproject.com/ticket/28408>
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