django - 属性错误 : myview has no attribute object in custom mixin in Django

Question

我正在尝试写一个 mixin能够部分保存表格并稍后恢复。当表单很长且用户无法一次完成时，这很有用。 mixin下面的代码直接来自 prodjango马蒂·阿尔钦 (Marty Alchin) 的书。我在错误出现的代码中评论了 POST method在 mixin.详细的错误描述如下。

从回溯来看，我认为错误来自这两个调用 self.get_form(form_class)和 get_form_kwargs .但我不知道如何解决这个问题。

这是 view :

class ArticleCreateView(PendFormMixin, CreateView):
      form_class = ArticleForm
      model = Article
      template_name = "article_create.html"
      success_url = '/admin'

这是 mixin :

from django.views.generic.edit import FormView
from pend_form.models import PendedForm, PendedValue
from hashlib import md5



class PendFormMixin(object):
    form_hash_name = 'form_hash'
    pend_button_name = 'pend'
    def get_form_kwargs(self):
        """
        Returns a dictionary of arguments to pass into the form instantiation.
        If resuming a pended form, this will retrieve data from the database.
        """
        form_hash = self.kwargs.get(self.form_hash_name)
        print "form_hash", form_hash
        if form_hash:
            import_path = self.get_import_path(self.get_form_class())
            return {'data': self.get_pended_data(import_path, form_hash)}
        else:
            print "called"
            # print super(PendFormMixin, self).get_form_kwargs()
            return super(PendFormMixin, self).get_form_kwargs()

    def post(self, request, *args, **kwargs):
        """
        Handles POST requests with form data. If the form was pended, it doesn't follow
        the normal flow, but saves the values for later instead.
        """
        if self.pend_button_name in self.request.POST:
            print "here"
            form_class = self.get_form_class()
            print form_class
            form = self.get_form(form_class)
             #the error happens here. below print is not executed
            # print "form is ", form
            self.form_pended(form)
        else:
            super(PendFormMixin, self).post(request, *args, **kwargs)

# Custom methods follow
    def get_import_path(self, form_class):
        return '{0}.{1}'.format(form_class.__module__, form_class.__name__)
    def get_form_hash(self, form):
        content = ','.join('{0}:{1}'.format(n, form.data[n]) for n in form.fields.keys())
        return md5(content).hexdigest()
    def form_pended(self, form):
        import_path = self.get_import_path(self.get_form_class())
        form_hash = self.get_form_hash(form)
        print "in form_pended"
        pended_form = PendedForm.objects.get_or_create(form_class=import_path,
                                                       hash=form_hash)
        for name in form.fields.keys():
            pended_form.data.get_or_create(name=name, value=form.data[name])
        return form_hash
    def get_pended_data(self, import_path, form_hash):
        data = PendedValue.objects.filter(import_path=import_path, form_hash=form_hash)
        return dict((d.name, d.value) for d in data)

错误:

'ArticleCreateView' object has no attribute 'object'
Exception Location:     /Users/django/django/lib/python2.7/site-packages/django/views/generic/edit.py in get_form_kwargs, line 125


/Users/pend_form/forms.py in post

                form = self.get_form(form_class)

/Users/django/django/lib/python2.7/site-packages/django/views/generic/edit.py in get_form_kwargs

            kwargs.update({'instance': self.object})

Answer 1

如果您查看 django 的 CreateView 或其父级 BaseCreateView 的定义，您会发现它所做的只是分配 self.object = None 在调用定义实际表单行为的父类(super class)方法之前。那是因为它是一个 CreateView - 可能不存在要编辑的对象。

由于您的 mixin 覆盖了此行为，因此机器的其余部分在期望 self.object 以 None 形式存在时失败。

将 self.object = None 添加到 def post 方法的第一行。