#30044: F expressions don't work with MTI
-------------------------------------+-------------------------------------
Reporter: Tom | Owner: nobody
Carrick |
Type: Bug | Status: new
Component: Database | Version: 2.1
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
First, I'm not sure if it is or should be possible to do this, but I think
at least the error message could be improved.
{{{
class Parent(models.Model):
date_x = models.DateTimeField(blank=True, null=True)
class Child(Parent):
date_y = models.DateTimeField(blank=True, null=True)
>>> Child.objects.update(date_y=F('date_x'))
Traceback (most recent call last):
File "/Users/tom/.local/share/virtualenvs/test-PwakbHlc/lib/python3.6
/site-packages/django/db/backends/utils.py", line 85, in _execute
return self.cursor.execute(sql, params)
File "/Users/tom/.local/share/virtualenvs/test-PwakbHlc/lib/python3.6
/site-packages/django/db/backends/sqlite3/base.py", line 296, in execute
return Database.Cursor.execute(self, query, params)
sqlite3.OperationalError: no such column: mtitest_parent.date_x
}}}
This error is confusing as it says it's looking at the parent model, but
the field is right there on the parent model.
On another project using postgres, the error is better but it makes it
seem like a bug in django (not sure if it is or isn't):
{{{
>>> Project.objects.update(deactivation_date=F('last_activity'))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/local/lib/python3.5/site-
packages/django/db/models/manager.py", line 82, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "/usr/local/lib/python3.5/site-packages/django/db/models/query.py",
line 695, in update
rows = query.get_compiler(self.db).execute_sql(CURSOR)
File "/usr/local/lib/python3.5/site-
packages/django/db/models/sql/compiler.py", line 1379, in execute_sql
cursor = super().execute_sql(result_type)
File "/usr/local/lib/python3.5/site-
packages/django/db/models/sql/compiler.py", line 1068, in execute_sql
cursor.execute(sql, params)
File "/usr/local/lib/python3.5/site-
packages/django/db/backends/utils.py", line 100, in execute
return super().execute(sql, params)
File "/usr/local/lib/python3.5/site-
packages/raven/contrib/django/client.py", line 123, in execute
return real_execute(self, sql, params)
File "/usr/local/lib/python3.5/site-
packages/django/db/backends/utils.py", line 68, in execute
return self._execute_with_wrappers(sql, params, many=False,
executor=self._execute)
File "/usr/local/lib/python3.5/site-
packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
return executor(sql, params, many, context)
File "/usr/local/lib/python3.5/site-
packages/django/db/backends/utils.py", line 85, in _execute
return self.cursor.execute(sql, params)
File "/usr/local/lib/python3.5/site-packages/django/db/utils.py", line
89, in __exit__
raise dj_exc_value.with_traceback(traceback) from exc_value
File "/usr/local/lib/python3.5/site-
packages/django/db/backends/utils.py", line 85, in _execute
return self.cursor.execute(sql, params)
django.db.utils.ProgrammingError: missing FROM-clause entry for table
"content_contentmodel"
LINE 1: ...DATE "projects_project" SET "deactivation_date" = "content_c...
^
missing FROM-clause entry for table "content_contentmodel"
LINE 1: ...DATE "projects_project" SET "deactivation_date" = "content_c...
}}}
I don't know if it's possible to fix this, but if not it would be nice if
the user could be informed this isn't possible.
--
Ticket URL: <https://code.djangoproject.com/ticket/30044>
Django <https://code.djangoproject.com/>
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