Django Modelform(带有排除字段)

Question

我有一个示例表格:

class AdminDiscountForm(ModelForm):  
    class Meta:  
        model = Discount  
        exclude = ('company',)

它指向的模型是:

class Discount(models.Model):
    class Meta:
        verbose_name=_('Discount')
        verbose_name_plural=_('Discounts')
        unique_together = ('company','type')

    company = models.ForeignKey(Company)
    type = models.CharField(max_length=5, choices=DISCOUNT_CHOICES)
    discount = models.DecimalField(max_digits=7, decimal_places=2, verbose_name=_('Discount'))

该表单排除了"公司"字段,因为用户已使用UI选择了此字段.

我打算做一个:

company = blah
if form.is_valid():
    obj = form.save(commit=False)
    obj.company = company
    obj.save()

问题是'company'和'type'的组合应该是唯一的(因此'unique_together').这是在数据库中强制执行的,所以django并不关心.我需要扩展此表单的clean()方法以检查唯一性:

def clean(self):
    cleaned_data = self.cleaned_data
    # check for uniqueness of 'company' and 'type'

这里的问题是'公司'不在那里,因为它被排除在外.在这种情况下,提出表单验证错误的最佳方法是什么？

- 编辑这仅用于添加折扣条目.没有初始实例.

Answer 1

Jammon的方法是我使用的方法.扩展一下(使用你的例子):

models.py

class Discount(models.Model):
    class Meta:
        verbose_name=_('Discount')
        verbose_name_plural=_('Discounts')
        unique_together = ('company','type')

    company = models.ForeignKey(Company)
    type = models.CharField(max_length=5, choices=DISCOUNT_CHOICES)
    discount = models.DecimalField(max_digits=7, decimal_places=2, verbose_name=_('Discount'))

forms.py

class AdminDiscountForm(ModelForm):  
    class Meta:  
        model = Discount  
        exclude = ('company',)

views.py

def add_discount(request, company_id=None):
    company = get_object_or_404(Company, company_id)

    discount=Discount(company=company)

    if request.method == 'post':
        form = AdminDiscountForm(request.POST, instance=discount)
        if form.is_valid():
            form.save()
            return HttpResponse('Success')
    else:
        form = AdminDiscountForm(instance=company)

    context = { 'company':company,
                'form':form,}

    return render_to_response('add-discount.html', context,
        context_instance=RequestContext(request))

这可以通过创建折扣模型的实例,然后将表单绑定到此实例来实现.此实例不会保存到您的数据库,但用于绑定表单.此绑定表单具有绑定实例的公司值.然后将其发送到您的模板以供用户填写.当用户提交此表单并验证表单时,模型验证检查将检查Meta中定义的唯一一起的唯一性.

见Model Validation Docs和overriding clean for ModelForms

编辑:

你可以做一些事情来捕捉非独特的一起进入尝试.

1. 在你的form.is_valid()中你可以除了这样的完整性错误:

   if request.method == 'post':
       form = AdminDiscountForm(request.POST, instance=discount)
       if form.is_valid():
           try:
               form.save()
               return HttpResponse('Success')
           except IntegrityError:
               form._errors["company"] = "some message"
               form._errors["type"] = "some message"
       else:
           ...
   

2. 在模型表单的clean方法中使用self.instance来检查唯一性.