Django模板中的分组CheckboxSelectMultiple

Question

如何将CheckboxSelectMultiple 生成的复选框按相关模型分组？

这是最好的例子。

models.py：

class FeatureCategory(models.Model):
    name = models.CharField(max_length=30)

class Feature(models.Model):
    name = models.CharField(max_length=30)
    category = models.ForeignKey(FeatureCategory)

class Widget(models.Model):
    name = models.CharField(max_length=30)
    features = models.ManyToManyField(Feature, blank=True)

forms.py：

class WidgetForm(forms.ModelForm):
    features = forms.ModelMultipleChoiceField(
        queryset=Feature.objects.all(),
        widget=forms.CheckboxSelectMultiple,
        required=False
    )
    class Meta:
        model = Widget

views.py：

def edit_widget(request):
    form = WidgetForm()
    return render(request, 'template.html', {'form': form})

template.html：

{{ form.as_p }}

以上产生以下输出：

[] Widget 1
[] Widget 2
[] Widget 3
[] Widget 1
[] Widget 2

我想要按功能类别对功能复选框进行分组（基于ForeignKey）：

Category 1:
  [] Widget 1
  [] Widget 2
  [] Widget 3

Category 2:
  [] Widget 1
  [] Widget 2

我怎样才能做到这一点？我尝试使用{% regroup %} 模板标签无济于事。

非常感谢任何建议。

谢谢。

Answer 1

您必须编写自定义 CheckboxSelectMultiple 小部件。使用snippet，我尝试通过在字段attrs 中添加category_name 作为属性来使CheckboxSelectMultiple 字段可迭代。这样我以后可以在模板中使用regroup标签。

下面的代码是根据你的需要从sn-p修改而来的，显然这段代码可以变得更简洁更通用，但此时它不是通用的。

forms.py

from django import forms
from django.forms import Widget
from django.forms.widgets import SubWidget
from django.forms.util import flatatt
from django.utils.html import conditional_escape
from django.utils.encoding import StrAndUnicode, force_unicode
from django.utils.safestring import mark_safe

from itertools import chain
import ast

from mysite.models import Widget as wid # your model name is conflicted with django.forms.Widget
from mysite.models import Feature

class CheckboxInput(SubWidget):
    """
    An object used by CheckboxRenderer that represents a single
    <input type='checkbox'>.
    """
    def __init__(self, name, value, attrs, choice, index):
        self.name, self.value = name, value
        self.attrs = attrs
        self.choice_value = force_unicode(choice[1])
        self.choice_label = force_unicode(choice[2])

        self.attrs.update({'cat_name': choice[0]})

        self.index = index

    def __unicode__(self):
        return self.render()

    def render(self, name=None, value=None, attrs=None, choices=()):
        name = name or self.name
        value = value or self.value
        attrs = attrs or self.attrs

        if 'id' in self.attrs:
            label_for = ' for="%s_%s"' % (self.attrs['id'], self.index)
        else:
            label_for = ''
        choice_label = conditional_escape(force_unicode(self.choice_label))
        return mark_safe(u'<label%s>%s %s</label>' % (label_for, self.tag(), choice_label))

    def is_checked(self):
        return self.choice_value in self.value

    def tag(self):
        if 'id' in self.attrs:
            self.attrs['id'] = '%s_%s' % (self.attrs['id'], self.index)
        final_attrs = dict(self.attrs, type='checkbox', name=self.name, value=self.choice_value)
        if self.is_checked():
            final_attrs['checked'] = 'checked'
        return mark_safe(u'<input%s />' % flatatt(final_attrs))

class CheckboxRenderer(StrAndUnicode):
    def __init__(self, name, value, attrs, choices):
        self.name, self.value, self.attrs = name, value, attrs
        self.choices = choices

    def __iter__(self):
        for i, choice in enumerate(self.choices):
            yield CheckboxInput(self.name, self.value, self.attrs.copy(), choice, i)

    def __getitem__(self, idx):
        choice = self.choices[idx] # Let the IndexError propogate
        return CheckboxInput(self.name, self.value, self.attrs.copy(), choice, idx)

    def __unicode__(self):
        return self.render()

    def render(self):
        """Outputs a <ul> for this set of checkbox fields."""
        return mark_safe(u'<ul>\n%s\n</ul>' % u'\n'.join([u'<li>%s</li>'
                % force_unicode(w) for w in self]))

class CheckboxSelectMultipleIter(forms.CheckboxSelectMultiple):
    """
    Checkbox multi select field that enables iteration of each checkbox
    Similar to django.forms.widgets.RadioSelect
    """
    renderer = CheckboxRenderer

    def __init__(self, *args, **kwargs):
        # Override the default renderer if we were passed one.
        renderer = kwargs.pop('renderer', None)
        if renderer:
            self.renderer = renderer
        super(CheckboxSelectMultipleIter, self).__init__(*args, **kwargs)

    def subwidgets(self, name, value, attrs=None, choices=()):
        for widget in self.get_renderer(name, value, attrs, choices):
            yield widget

    def get_renderer(self, name, value, attrs=None, choices=()):
        """Returns an instance of the renderer."""

        choices_ = [ast.literal_eval(i[1]).iteritems() for i in self.choices]
        choices_ = [(a[1], b[1], c[1]) for a, b, c in choices_]

        if value is None: value = ''
        str_values = set([force_unicode(v) for v in value]) # Normalize to string.
        if attrs is None:
            attrs = {}
        if 'id' not in attrs:
            attrs['id'] = name
        final_attrs = self.build_attrs(attrs)
        choices = list(chain(choices_, choices))
        return self.renderer(name, str_values, final_attrs, choices)

    def render(self, name, value, attrs=None, choices=()):
        return self.get_renderer(name, value, attrs, choices).render()

    def id_for_label(self, id_):
        if id_:
            id_ += '_0'
        return id_

class WidgetForm(forms.ModelForm):
    features = forms.ModelMultipleChoiceField(
        queryset=Feature.objects.all().values('id', 'name', 'category__name'),
        widget=CheckboxSelectMultipleIter,
        required=False
    )
    class Meta:
        model = wid

然后在模板中：

{% for field in form %}
{% if field.name == 'features' %} 
    {% regroup field by attrs.cat_name as list %}

    <ul>
    {% for el in list %}
        <li>{{el.grouper}}
        <ul>
            {% for e in el.list %}
                {{e}} <br />
            {% endfor %}
        </ul>
        </li>
    {% endfor %}
    </ul>
{% else %}
    {{field.label}}: {{field}}
{% endif %}

{% endfor %}

结果： 我在类别表中添加了国家名称，在特征表中添加了城市名称，因此在模板中我能够根据国家（类别）重新组合城市（特征）

Answer 2

这是当前版本的 Django (~2.1) 的解决方案。

## forms.py

from itertools import groupby
from django import forms
from django.forms.models import ModelChoiceIterator, ModelMultipleChoiceField

from .models import Feature, Widget


class GroupedModelMultipleChoiceField(ModelMultipleChoiceField):

    def __init__(self, group_by_field, group_label=None, *args, **kwargs):
        """
        ``group_by_field`` is the name of a field on the model
        ``group_label`` is a function to return a label for each choice group

        """
        super(GroupedModelMultipleChoiceField, self).__init__(*args, **kwargs)
        self.group_by_field = group_by_field
        if group_label is None:
            self.group_label = lambda group: group
        else:
            self.group_label = group_label

    def _get_choices(self):
        if hasattr(self, '_choices'):
            return self._choices
        return GroupedModelChoiceIterator(self)
    choices = property(_get_choices, ModelMultipleChoiceField._set_choices)


class GroupedModelChoiceIterator(ModelChoiceIterator):

    def __iter__(self):
        """Now yields grouped choices."""            
        if self.field.empty_label is not None:
            yield ("", self.field.empty_label)
        for group, choices in groupby(
                self.queryset.all(),
                lambda row: getattr(row, self.field.group_by_field)):
            if group is None:
                for ch in choices:
                    yield self.choice(ch)
            else:
                yield (
                    self.field.group_label(group),
                    [self.choice(ch) for ch in choices])


class WidgetForm(forms.ModelForm):
    class Meta:
        model = Widget
        fields = ['features',]

    def __init__(self, *args, **kwargs):
        super(WidgetForm, self).__init__(*args, **kwargs)
        self.fields['features'] = GroupedModelMultipleChoiceField(
            group_by_field='category',
            queryset=Feature.objects.all(),
            widget=forms.CheckboxSelectMultiple(),
            required=False)

然后您可以在模板中使用{{ form.as_p }} 进行正确分组的选择。

如果您想使用 regroup 模板标签并遍历选项，您还需要引用以下自定义小部件：

class GroupedCheckboxSelectMultiple(forms.CheckboxSelectMultiple):

    def optgroups(self, name, value, attrs=None):
        """
        The group name is passed as an argument to the ``create_option`` method (below).

        """
        groups = []
        has_selected = False

        for index, (option_value, option_label) in enumerate(self.choices):
            if option_value is None:
                option_value = ''

            subgroup = []
            if isinstance(option_label, (list, tuple)):
                group_name = option_value
                subindex = 0
                choices = option_label
            else:
                group_name = None
                subindex = None
                choices = [(option_value, option_label)]
            groups.append((group_name, subgroup, index))

            for subvalue, sublabel in choices:
                selected = (
                    str(subvalue) in value and
                    (not has_selected or self.allow_multiple_selected)
                )
                has_selected |= selected
                subgroup.append(self.create_option(
                    name, subvalue, sublabel, selected, index,
                    subindex=subindex, attrs=attrs, group=group_name,
                ))
                if subindex is not None:
                    subindex += 1
        return groups

    def create_option(self, name, value, label, selected, index, subindex=None, attrs=None, group=None):
        """
        Added a ``group`` argument which is included in the returned dictionary.

        """
        index = str(index) if subindex is None else "%s_%s" % (index, subindex)
        if attrs is None:
            attrs = {}
        option_attrs = self.build_attrs(self.attrs, attrs) if self.option_inherits_attrs else {}
        if selected:
            option_attrs.update(self.checked_attribute)
        if 'id' in option_attrs:
            option_attrs['id'] = self.id_for_label(option_attrs['id'], index)
        return {
            'name': name,
            'value': value,
            'label': label,
            'selected': selected,
            'index': index,
            'attrs': option_attrs,
            'type': self.input_type,
            'template_name': self.option_template_name,
            'wrap_label': True,
            'group': group,
        }


class WidgetForm(forms.ModelForm):
    class Meta:
        model = Widget
        fields = ['features',]

    def __init__(self, *args, **kwargs):
        super(WidgetForm, self).__init__(*args, **kwargs)
        self.fields['features'] = GroupedModelMultipleChoiceField(
            group_by_field='category',
            queryset=Feature.objects.all(),
            widget=GroupedCheckboxSelectMultiple(),
            required=False)

那么以下内容应该可以在您的模板中使用：

{% regroup form.features by data.group as feature_list %}
{% for group in feature_list %}
<h6>{{ group.grouper|default:"Other Features" }}</h6>
<ul>
  {% for choice in group.list %}
  <li>{{ choice }}</li>
  {% endfor %}
</ul>
</div>
{% endfor %}

部分解决方案归功于以下页面：

https://mounirmesselmeni.github.io/2013/11/25/django-grouped-select-field-for-modelchoicefield-or-modelmultiplechoicefield/