#34807: importing `django.forms` causes circular import error
---------------------------------+------------------------------------
Reporter: Collin Anderson | Owner: nobody
Type: Bug | Status: new
Component: Forms | Version: dev
Severity: Release blocker | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
---------------------------------+------------------------------------
Changes (by Tim Graham):
* stage: Unreviewed => Accepted
* severity: Normal => Release blocker
Old description:
> circular import between forms and models and choices.
>
> before 500e01073adda32d514962 you could import forms just fine.
>
> {{{
> git checkout 500e01073adda32d514962^
> python3 -c"from django.db import models" # works fine
> python3 -c"from django import forms" # works fine
> }}}
>
> but since 500e01073adda32d514962 this hasn't worked due to circular
> import.
>
> {{{
> git checkout 500e01073adda32d514962
> python3 -c"from django.db import models" # works fine
> python3 -c"from django import forms" # fails:
>
> Traceback (most recent call last):
> File "<string>", line 1, in <module>
> File "django/forms/__init__.py", line 6, in <module>
> from django.forms.boundfield import * # NOQA
> File "django/forms/boundfield.py", line 5, in <module>
> from django.forms.widgets import MultiWidget, Textarea, TextInput
> File "django/forms/widgets.py", line 15, in <module>
> from django.utils.choices import normalize_choices
> File "django/utils/choices.py", line 3, in <module>
> from django.db.models.enums import ChoicesMeta
> File "django/db/models/__init__.py", line 3, in <module>
> from django.db.models.aggregates import * # NOQA
> File "django/db/models/aggregates.py", line 5, in <module>
> from django.db.models.expressions import Case, Func, Star, Value,
> When
> File "django/db/models/expressions.py", line 12, in <module>
> from django.db.models import fields
> File "django/db/models/fields/__init__.py", line 18, in <module>
> from django.utils.choices import CallableChoiceIterator,
> normalize_choices
> ImportError: cannot import name 'CallableChoiceIterator' from partially
> initialized module 'django.utils.choices' (most likely due to a circular
> import) (django/utils/choices.py)
>
> python3 -c"from django.utils import choices" # also fails:
>
> Traceback (most recent call last):
> File "<string>", line 1, in <module>
> File "django/utils/choices.py", line 3, in <module>
> from django.db.models.enums import ChoicesMeta
> File "django/db/models/__init__.py", line 3, in <module>
> from django.db.models.aggregates import * # NOQA
> File "django/db/models/aggregates.py", line 5, in <module>
> from django.db.models.expressions import Case, Func, Star, Value,
> When
> File "django/db/models/expressions.py", line 12, in <module>
> from django.db.models import fields
> File "django/db/models/fields/__init__.py", line 10, in <module>
> from django import forms
> File "django/forms/__init__.py", line 6, in <module>
> from django.forms.boundfield import * # NOQA
> File "django/forms/boundfield.py", line 5, in <module>
> from django.forms.widgets import MultiWidget, Textarea, TextInput
> File "django/forms/widgets.py", line 15, in <module>
> from django.utils.choices import normalize_choices
> ImportError: cannot import name 'normalize_choices' from partially
> initialized module 'django.utils.choices' (most likely due to a circular
> import) (django/utils/choices.py)
> }}}
>
> Models has always had a dependency on Forms, but now Models depends on
> Forms depends on `utils.choices` which depend on
> `models.enums.ChoicesMeta`
>
> Summary of the circle: `django.forms` -> 'forms.widgets` ->
> `django.utils.choices` -> `django.db.models.enums` -> `models.__init__`
> -> `models.aggregates` -> `models.fields` -> `django.forms`
>
> If `django.db.models` is imported before forms then it happens to import
> fine because the order of imports happens to lines up perfectally, but
> it's very very fragile. `models.__init__` -> `models.aggregates` ->
> `models.fields` -> `django.forms` -> 'forms.widgets` ->
> `django.utils.choices` -> `django.db.models.enums`.
New description:
circular import between forms and models and choices.
before [500e01073adda32d514962] you could import forms just fine.
{{{
git checkout 500e01073adda32d514962^
python3 -c"from django.db import models" # works fine
python3 -c"from django import forms" # works fine
}}}
but since [500e01073adda32d514962] this hasn't worked due to circular
import.
{{{
git checkout 500e01073adda32d514962
python3 -c"from django.db import models" # works fine
python3 -c"from django import forms" # fails:
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "django/forms/__init__.py", line 6, in <module>
from django.forms.boundfield import * # NOQA
File "django/forms/boundfield.py", line 5, in <module>
from django.forms.widgets import MultiWidget, Textarea, TextInput
File "django/forms/widgets.py", line 15, in <module>
from django.utils.choices import normalize_choices
File "django/utils/choices.py", line 3, in <module>
from django.db.models.enums import ChoicesMeta
File "django/db/models/__init__.py", line 3, in <module>
from django.db.models.aggregates import * # NOQA
File "django/db/models/aggregates.py", line 5, in <module>
from django.db.models.expressions import Case, Func, Star, Value, When
File "django/db/models/expressions.py", line 12, in <module>
from django.db.models import fields
File "django/db/models/fields/__init__.py", line 18, in <module>
from django.utils.choices import CallableChoiceIterator,
normalize_choices
ImportError: cannot import name 'CallableChoiceIterator' from partially
initialized module 'django.utils.choices' (most likely due to a circular
import) (django/utils/choices.py)
python3 -c"from django.utils import choices" # also fails:
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "django/utils/choices.py", line 3, in <module>
from django.db.models.enums import ChoicesMeta
File "django/db/models/__init__.py", line 3, in <module>
from django.db.models.aggregates import * # NOQA
File "django/db/models/aggregates.py", line 5, in <module>
from django.db.models.expressions import Case, Func, Star, Value, When
File "django/db/models/expressions.py", line 12, in <module>
from django.db.models import fields
File "django/db/models/fields/__init__.py", line 10, in <module>
from django import forms
File "django/forms/__init__.py", line 6, in <module>
from django.forms.boundfield import * # NOQA
File "django/forms/boundfield.py", line 5, in <module>
from django.forms.widgets import MultiWidget, Textarea, TextInput
File "django/forms/widgets.py", line 15, in <module>
from django.utils.choices import normalize_choices
ImportError: cannot import name 'normalize_choices' from partially
initialized module 'django.utils.choices' (most likely due to a circular
import) (django/utils/choices.py)
}}}
Models has always had a dependency on Forms, but now Models depends on
Forms depends on `utils.choices` which depend on
`models.enums.ChoicesMeta`
Summary of the circle: `django.forms` -> `forms.widgets` ->
`django.utils.choices` -> `django.db.models.enums` -> `models.__init__` ->
`models.aggregates` -> `models.fields` -> `django.forms`.
If `django.db.models` is imported before forms then it happens to import
fine because the order of imports happens to lines up perfectally, but
it's very very fragile. `models.__init__` -> `models.aggregates` ->
`models.fields` -> `django.forms` -> `forms.widgets` ->
`django.utils.choices` -> `django.db.models.enums`.
--
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Ticket URL: <https://code.djangoproject.com/ticket/34807#comment:1>
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