can't bulk create models with no fields

[ellery-newcomer@…]

I have a model

class Discussion(models.Model): pass

I try to do this:

discussions = [Discussion() for i in range(n)]
Discussion.objects.bulk_create(discussions)

it fails with

AttributeError: 'NoneType' object has no attribute 'column'

because

django.db.models.sql.compiler.SQLInsertCompiler.as_sql has the following line in it:

fields = [None]

which doesn't get tripped on models that have fields, apparently.

[Tim Graham]

Can reproduce with the attached test for Django's test suite.

[Chris Luc]

I've modified the compiler to create the below query, but I'm getting an Integrity Error: datatype mismatch when I run it in Django. I assume it's because id is a pk and it doesn't accept NULL values, but it seems to work on my own sqlite. Does anyone know how to solve this issue?

We use the second form of bulk inserting, ref ​https://www.sqlite.org/lang_insert.html

u'INSERT INTO "bulk_create_nofields" ("id") SELECT %s UNION ALL SELECT %s UNION ALL SELECT %s', (u'NULL', u'NULL', u'NULL'))

Traceback (most recent call last):
  File "/Users/chrisjluc/Documents/opensource/django/tests/bulk_create/tests.py", line 172, in test_empty_model
    NoFields.objects.bulk_create(objs)
  File "/Users/chrisjluc/Documents/opensource/django/django/db/models/manager.py", line 127, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/Users/chrisjluc/Documents/opensource/django/django/db/models/query.py", line 445, in bulk_create
    self._batched_insert(objs_without_pk, fields, batch_size)
  File "/Users/chrisjluc/Documents/opensource/django/django/db/models/query.py", line 1043, in _batched_insert
    using=self.db)
  File "/Users/chrisjluc/Documents/opensource/django/django/db/models/manager.py", line 127, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/Users/chrisjluc/Documents/opensource/django/django/db/models/query.py", line 1026, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/Users/chrisjluc/Documents/opensource/django/django/db/models/sql/compiler.py", line 974, in execute_sql
    cursor.execute(sql, params)
  File "/Users/chrisjluc/Documents/opensource/django/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/Users/chrisjluc/Documents/opensource/django/django/db/utils.py", line 95, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/Users/chrisjluc/Documents/opensource/django/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/Users/chrisjluc/Documents/opensource/django/django/db/backends/sqlite3/base.py", line 318, in execute
    return Database.Cursor.execute(self, query, params)
IntegrityError: datatype mismatch

[Tim Graham]

Fixed in Django 1.9 by 134ca4d438bd7cbe8f0f287a00d545f96fa04a01.

​PR to add a regression test.

[Simon Charette]

Regression test LGTM.

[Tim Graham <timograham@…>]

In 7a5b7e35:

Fixed #22705 -- Fixed QuerySet.bulk_create() on models without any fields on Oracle.

Fixed on other backends by 134ca4d438bd7cbe8f0f287a00d545f96fa04a01.

Thanks Mariusz Felisiak for the solution.

[Tim Graham <timograham@…>]

In 7cd2995:

[1.9.x] Fixed #22705 -- Fixed QuerySet.bulk_create() on models without any fields on Oracle.

Fixed on other backends by 134ca4d438bd7cbe8f0f287a00d545f96fa04a01.

Thanks Mariusz Felisiak for the solution.

Backport of 7a5b7e35bf2e219225b9f26d3dd3e34f26e83e9c from master