#27331 closed New feature (wontfix)
Proposed opt_group argument for ModelChoiceField and ModelMultipleChoiceField
Reported by: | Héctor Urbina | Owned by: | nobody |
---|---|---|---|
Component: | Forms | Version: | dev |
Severity: | Normal | Keywords: | ModelChoiceField optgroup |
Cc: | Triage Stage: | Unreviewed | |
Has patch: | no | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description (last modified by )
Hello,
I've just implemented this and I thought It could well be incorporated into Django itself; I guess it's a fairly common feature that one may need on any project.
What I propose is to add an optional opt_group
argument to ModelChoiceField and ModelMultipleChoiceField; which indicates the item's field whose value is used to group the choices. It should be used in conjunction with a queryset which is (primarily) sorted by the same field.
Let me show with an example:
class Category(models.Model): name = models.CharField(max_length=20) class Item(models.Model): name = models.CharField(max_length=20) category = models.ForeignKey(Category)
And in some form's initialization process
field = ModelChoiceField(queryset=Item.objects.order_by('category__name', 'name'), opt_group='category')
field.choices
will dynamically collect choices into named groups as a 2-tuple, which the underlying widget should present using optgroup
HTML elements.
Change History (8)
comment:1 by , 8 years ago
Description: | modified (diff) |
---|
follow-up: 3 comment:2 by , 8 years ago
Has patch: | unset |
---|
comment:3 by , 8 years ago
Replying to Tim Graham:
At first glance, that looks more appropriate as a widget option since
ModelChoiceField
isn't required to use aSelect
widget.
The default ModelChoiceField
's widget (Select
) is prepared to understand 2-tuples coming on the field's choices attribute and translates them to optgroups.
ModelChoiceField
uses ModelChoiceIterator
to generate the choices; that is the actual class that is doing the job on my current implementation. My idea is to include support for optgroup, not require it; I'm updating my proposal to clarify that.
comment:4 by , 8 years ago
Description: | modified (diff) |
---|
comment:5 by , 8 years ago
I'm still unconvinced that adding an argument with an HTML looking name to a model field that only affects selected widgets is a good design. I see that it's convenient compared to the alternative of providing a custom ModelChoiceIterator
but I don't know that the coupling is a good design.
comment:6 by , 8 years ago
Resolution: | → wontfix |
---|---|
Status: | new → closed |
As the discussion has stalled here, you can write to the DevelopersMailingList for other opinions. Thanks.
follow-up: 8 comment:7 by , 6 years ago
By the way, this is currently possible with the following code
from functools import partial from itertools import groupby from operator import attrgetter class GroupedModelChoiceIterator(ModelChoiceIterator): def __init__(self, field, groupby): self.groupby = groupby super().__init__(field) def __iter__(self): if self.field.empty_label is not None: yield ("", self.field.empty_label) queryset = self.queryset # Can't use iterator() when queryset uses prefetch_related() if not queryset._prefetch_related_lookups: queryset = queryset.iterator() for group, objs in groupby(queryset, self.groupby): yield (group, [self.choice(obj) for obj in objs]) class GroupedModelChoiceField(ModelChoiceField): def __init__(self, *args, choices_groupby, **kwargs): if isinstance(choices_groupby, str): choices_groupby = attrgetter(choices_groupby) elif not callable(choices_groupby): raise TypeError('choices_groupby must either be a str or a callable accepting a single argument') self.iterator = partial(GroupedModelChoiceIterator, groupby=choices_groupby) super().__init__(*args, **kwargs)
While I won't push to get this feature included I think that a request for feedback on django-developers has a good chance of being accepted. It looks like the main argument against closing this ticket as _wontfix_ was the naming of the ModelChoice(opt_group)
argument which was effectively leaking HTML implementation details at the form layer.
comment:8 by , 4 years ago
Replying to Simon Charette:
By the way, this is currently possible with the following code
from functools import partial from itertools import groupby from operator import attrgetter class GroupedModelChoiceIterator(ModelChoiceIterator): def __init__(self, field, groupby): self.groupby = groupby super().__init__(field) def __iter__(self): if self.field.empty_label is not None: yield ("", self.field.empty_label) queryset = self.queryset # Can't use iterator() when queryset uses prefetch_related() if not queryset._prefetch_related_lookups: queryset = queryset.iterator() for group, objs in groupby(queryset, self.groupby): yield (group, [self.choice(obj) for obj in objs]) class GroupedModelChoiceField(ModelChoiceField): def __init__(self, *args, choices_groupby, **kwargs): if isinstance(choices_groupby, str): choices_groupby = attrgetter(choices_groupby) elif not callable(choices_groupby): raise TypeError('choices_groupby must either be a str or a callable accepting a single argument') self.iterator = partial(GroupedModelChoiceIterator, groupby=choices_groupby) super().__init__(*args, **kwargs)While I won't push to get this feature included I think that a request for feedback on django-developers has a good chance of being accepted. It looks like the main argument against closing this ticket as _wontfix_ was the naming of the
ModelChoice(opt_group)
argument which was effectively leaking HTML implementation details at the form layer.
This solution no longer works as of this change: https://github.com/django/django/commit/5ec64f96b2d83ec3c0ef574f52e4767a440017b8
At first glance, that looks more appropriate as a widget option since
ModelChoiceField
isn't required to use aSelect
widget.