在Django中,我们可以通过表单的初始化参数initial
来传递自定义的初始值给表单字段。如果我们想要在视图中设置表单的初始值,可以在视图中创建表单的实例时,传递一个字典给initial
参数。
1、问题背景
我们遇到了这样一个问题:在使用 Django 表单时,我们希望将自定义表单中的值传递到视图中。然而,我们发现无法为多选选项的每个选项传递值。在渲染表单时,只有一个字符字段,而多选框中有多个选择。我们想知道是否有办法解决这个问题,以及表单集是否可以在这里提供帮助。我们对 Django 还很陌生,因此希望得到一些解释,以便更好地理解和学习。
python
# models.py
class StateOption(models.Model):
partstate = models.ForeignKey(State)
partoption = models.ForeignKey(Option)
relevantoutcome = models.ManyToManyField(Outcome, through='StateOptionOutcome')
class StateOptionOutcome(models.Model):
stateoption = models.ForeignKey(StateOption)
relevantoutcome = models.ForeignKey(Outcome)
outcomevalue = models.CharField(max_length=20)
# forms.py
class UpdateStateOptionWithOutcomesForm(forms.ModelForm):
class Meta:
model = StateOption
exclude = ['partstate', 'partoption']
def __init__(self, *args, **kwargs):
super(UpdateStateOptionWithOutcomesForm, self).__init__(*args, **kwargs)
self.fields['relevantoutcome'] = forms.ModelMultipleChoiceField(queryset=Outcome.objects.all(), required=True, widget=forms.CheckboxSelectMultiple)
self.fields['outcomevalue'] = forms.CharField(widget=forms.TextInput(attrs={'size': '30'}))
# views.py
stateoption = get_object_or_404(StateOption, pk=stateoption_id)
if request.method == "POST":
form = UpdateStateOptionWithOutcomesForm(request.POST, instance=stateoption)
if form.is_valid():
cd = form.cleaned_data
outcomevalue = cd['outcomevalue']
for outcome_id in request.POST.getlist('relevantoutcome'):
stateoption_outcome = StateOptionOutcome.objects.create(stateoption=stateoption, relevantoutcome_id=int(outcome_id), outcomevalue=outcomevalue)
# template.html
{% for field in form %}
{{ field.label }}:
{{ field }}
{% if field.errors %}
{{ field.errors|striptags }}
{% endif %}
{% endfor %}
2、解决方案
方法一:生成所需数量的字段
一种解决方案是编写一个循环来生成所需数量的字段。例如:
python
# forms.py
# ...
outcome_qs = Outcome.objects.all()
self.fields['relevantoutcome'] = forms.ModelMultipleChoiceField(queryset=outcome_qs, required=True, widget=forms.CheckboxSelectMultiple)
for outcome in outcome_qs:
# Use Outcome primary key to easily match two fields in your view.
self.fields['outcomevalue_%s' % outcome.pk] = forms.CharField(widget=forms.TextInput(attrs={'size':'30'})
方法二:使用表单集
另一种解决方案是使用表单集。表单集允许我们创建一组类似的表单,每个表单都可以处理单个对象。在我们的例子中,我们可以创建一个表单集来处理每个 StateOptionOutcome
对象。
python
# forms.py
class StateOptionOutcomeForm(forms.ModelForm):
class Meta:
model = StateOptionOutcome
fields = ['relevantoutcome', 'outcomevalue']
StateOptionOutcomeFormSet = forms.formset_factory(StateOptionOutcomeForm, extra=1)
# views.py
stateoption = get_object_or_404(StateOption, pk=stateoption_id)
if request.method == "POST":
formset = StateOptionOutcomeFormSet(request.POST)
if formset.is_valid():
for form in formset:
stateoption_outcome = StateOptionOutcome.objects.create(stateoption=stateoption, **form.cleaned_data)
使用表单集的好处是,我们可以轻松地处理多个对象,而且代码也更加简洁。