ModelChoiceField object has no attribute 'to_field_name' - Python

Формулировка задачи:

Делаю форму, где одно из полей - поле для выбора одного из вариантов (select). Варианты - значения из БД одной из моделей. В БД внес 14 наименований для модели blog_cat.

class blog_cat(models.Model):
    class Meta():
        db_table = "blog_Категории"
 
    blog_cat_name = models.CharField(unique=True, max_length=300, verbose_name="Название", help_text="Название")
 
    def __str__(self):
        return self.blog_cat_name
 
class blogs(models.Model):
    class Meta():
        db_table = "Блоги,рецепты,советы"
 
    blogs_title = models.CharField(max_length=300, verbose_name="Название Блога", help_text="Название Блога")
    blogs_cat = models.ForeignKey(blog_cat, verbose_name="Категория")
    blogs_user = models.ForeignKey(AuthUser, null=True, blank=True)
    blogs_date = models.DateTimeField(default=timezone.now())
    blogs_text = models.TextField(max_length=113000, null=True, blank=True, verbose_name="Текст", help_text="Текст")
    blogs_like = models.IntegerField(default=0, verbose_name="Лайки", null=True, blank=True)
    blogs_looks = models.IntegerField(default=0, verbose_name="Просмотров", null=True, blank=True)
 
    def __str__(self):
        return self.blogs_title

forms

class BlogForm(forms.ModelForm):
    class Meta():
        model = blogs
        fields = ['blogs_title', 'blogs_cat', 'blogs_text']
        widgets = {
            'blogs_title': forms.TextInput(attrs={'placeholder': 'Название', 'max_length': '313'}),
            'blogs_cat': forms.ModelChoiceField(queryset=blog_cat, empty_label=None, to_field_name="blog_cat_name"),
            'blogs_text': forms.Textarea(attrs={'placeholder': 'Текст', 'cols': 50, 'rows': 15}),
        }

Выдает ошибку:

AttributeError at / 'ModelChoiceField' object has no attribute 'to_field_name' Traceback

C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\core\handlers\base.py in get_response
                            resolver_match = resolver.resolve(request.path_info) ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\core\urlresolvers.py in resolve
                        for pattern in self.url_patterns: ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\core\urlresolvers.py in url_patterns
                    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module) ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\core\urlresolvers.py in urlconf_module
                        self._urlconf_module = import_module(self.urlconf_name) ...
? Local vars
C:\Python34\lib\importlib\__init__.py in import_module
                return _bootstrap._gcd_import(name[level:], package, level) ...
? Local vars
C:\Python34\nato4ka\nato4ka\urls.py in <module>
            from blogs import urls ...
? Local vars
C:\Python34\nato4ka\blogs\urls.py in <module>
            from blogs.views import * ...
? Local vars
C:\Python34\nato4ka\blogs\views.py in <module>
            from blogs.forms import * ...
? Local vars
C:\Python34\nato4ka\blogs\forms.py in <module>
            class BlogForm(forms.ModelForm): ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\forms\models.py in __new__
                                                  opts.help_texts, opts.error_messages) ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\forms\models.py in fields_for_model
                        formfield = f.formfield(**kwargs) ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\db\models\fields\related.py in formfield
                    return super(ForeignKey, self).formfield(**defaults) ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\db\models\fields\related.py in formfield
                    return super(RelatedField, self).formfield(**defaults) ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\db\models\fields\__init__.py in formfield
                    return form_class(**defaults) ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\forms\models.py in __init__
                    self.queryset = queryset ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\forms\models.py in _set_queryset
                    self.widget.choices = self.choices ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\forms\fields.py in _set_choices
                        value = list(value) ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\forms\models.py in __iter__
                            yield self.choice(obj) ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\forms\models.py in choice
                    return (self.field.prepare_value(obj), self.field.label_from_instance(obj)) ...
? Local vars
C:\Python34\lib\site-packages\django-1.8.3-py3.4.egg\django\forms\models.py in prepare_value
                        if self.to_field_name: ...
? Local vars

forms.ModelChoiceField(queryset=blog_cat.objects.all(), ....)

проблема осталась та же...

Решение задачи: «ModelChoiceField object has no attribute 'to_field_name'»

textual
                            Листинг программы 
                        

                            class BlogForm(forms.ModelForm):
    class Meta():
        model = blogs
        blogs_cat = forms.ModelChoiceField(queryset=blog_cat.objects.all(), empty_label=None, to_field_name="blog_cat_name")
        fields = ['blogs_title', 'blogs_cat', 'blogs_text']
        widgets = {
            'blogs_title': forms.TextInput(attrs={'placeholder': 'Название', 'max_length': '313'}),            
            'blogs_text': forms.Textarea(attrs={'placeholder': 'Текст', 'cols': 50, 'rows': 15}),
        }
                        