Fix bug: rename annotation_mask

[knqyf263]

Abstract

When the name of an existing field on the model is used as the alias name, annotate function renames the fields.

django-postgres-extra/psqlextra/manager/manager.py

Lines 46 to 57 in f4ce6ad

	# temporarily rename the fields that have the same
	# name as a field name, we'll rename them back after
	# the function in the base class ran
	new_annotations = {}
	renames = {}
	for name, value in annotations.items():
	if name in fields:
	new_name = '%s_new' % name
	new_annotations[new_name] = value
	renames[new_name] = name
	else:
	new_annotations[name] = value

After that, rename_annotations renames the fields to the original name again.

django-postgres-extra/psqlextra/query.py

Lines 34 to 44 in 76b6860

	for old_name, new_name in annotations.items():
	annotation = self.annotations.get(old_name)
	if not annotation:
	raise SuspiciousOperation((
	'Cannot rename annotation "{old_name}" to "{new_name}", because there'
	' is no annotation named "{old_name}".'
	).format(old_name=old_name, new_name=new_name))
	del self.annotations[old_name]
	self.annotations[new_name] = annotation

However, annotation_select_mask is not changed.
As a result, the renamed fields are lost because _annotation_select_cache is generated by annotation_select_mask.
https://github.com/django/django/blob/952f05a6db2665d83c04075119285f2164b03432/django/db/models/sql/query.py#L2022-L2027

In addition, though self.annotations is OrderedDict, order is destroyed in the following code.

django-postgres-extra/psqlextra/query.py

Lines 43 to 44 in 76b6860

	del self.annotations[old_name]
	self.annotations[new_name] = annotation

Sample

https://github.com/knqyf263/psqlextra_fix

In test_annotation_bug, description is not selected correctly.
https://github.com/knqyf263/psqlextra_fix/blob/master/users/tests.py#L10-L14

In test_union_exception, ValueError exception is thrown.
This is because the number of fields does not match the number of converters due to annotation_select_mask bug.
https://github.com/knqyf263/psqlextra_fix/blob/master/users/tests.py#L16-L23

Fix

• Chang to keep order of self.annotations.
• Also rename self.annotation_select_mask.

I'm not sure if this fix is correct, please review me!

[Photonios]

Awesome! Thanks a lot 👍

[knqyf263]

Thanks! I’m looking forward to release new version!