AttributeError: myview 在 Django 的自定义 mixin 中没有属性对象

Question

我正在尝试编写mixin 以便能够部分保存表单并稍后恢复。 当表单很长并且用户无法一次性完成时，这很有用。下面的mixin 代码直接来自Marty Alchin 的prodjango 书籍。我已经在错误出现的代码中注释了POST method in mixin. 下面详细的错误描述。

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。

这里是 view:

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

这里是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 BaseCreateView 的定义，您会发现它所做的只是在调用定义实际表单行为的超类方法之前分配 self.object = None。那是因为它是 CreateView - 不可能存在要编辑的对象。

由于你的 mixin 覆盖了这个行为，当它期望 self.object 以 None 存在时，其余的机器就会失败。

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

Answer 2

self.object 在post 中赋值，所以如果你覆盖post， 不要指望self.object 不会被分配，在你打电话给super(...).post(...)之前