起步

Django 表单中有两种字段类型可以使用选择框: ChoiceField 和 ModelChoiceField 。

对于 ChoiceField 的基本使用是:

class ExpenseForm(forms.Form): CHOICES = ( (11, 'Credit Card'), (12, 'Student Loans'), (13, 'Taxes'), (21, 'Books'), (22, 'Games'), (31, 'Groceries'), (32, 'Restaurants'), ) date = forms.DateField() category = forms.ChoiceField(choices=CHOICES)

它能渲染出:

使用分组下拉框

还可以使用如下方式生成 <optgourp> 标签：

class ExpenseForm(forms.Form): CHOICES = ( ('Debt', ( (11, 'Credit Card'), (12, 'Student Loans'), (13, 'Taxes'), )), ('Entertainment', ( (21, 'Books'), (22, 'Games'), )), ('Everyday', ( (31, 'Groceries'), (32, 'Restaurants'), )), ) date = forms.DateField() category = forms.ChoiceField(choices=CHOICES)

能够渲染为：

分组模型下拉框

如果使用的是 ModelChoiceField ，那抱歉，Django本身没有提供解决方案。

在 https://code.djangoproject.com/ticket/27331 中提供了一个很好的解决方案。

首先为需要分类的类型创建模型，在另一个模型中用外键关联它：

from django.db import modelsclass Category(models.Model): name = models.CharField(max_length=30) parent = models.ForeignKey('Category', on_delete=models.CASCADE, null=True) def __str__(self): return self.nameclass Expense(models.Model): amount = models.DecimalField(max_digits=10, decimal_places=2) date = models.DateField() category = models.ForeignKey(Category, on_delete=models.CASCADE) def __str__(self): return self.amount

其次，创建一个新的表单 Field 类型：

from functools import partialfrom itertools import groupbyfrom operator import attrgetterfrom django.forms.models import ModelChoiceIterator, ModelChoiceFieldclass 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)

最后，在表单中可以如下进行使用：

from django import formsfrom .fields import GroupedModelChoiceFieldfrom .models import Category, Expenseclass ExpenseForm(forms.ModelForm): category = GroupedModelChoiceField( queryset=Category.objects.exclude(parent=None), choices_groupby='parent' ) class Meta: model = Expense fields = ('amount', 'date', 'category')

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。