python网站：django覆写admin控件

from django import forms

class BlogAdminForm(forms.ModelForm):
    cate = models.Category.objects.all()
    cate_choices = []
    for item in cate:
        cate_choices.append((item.title, item.title))

    category = forms.ChoiceField(choices=cate_choices)
    class Meta:
        model = models.BlogPost
        fields = '__all__'
        widgets = {
            'body': AdminMarkdownWidget
        }

class BlogPostAdmin(admin.ModelAdmin):
    list_display = ('title', 'timestamp')
    readonly_fields = ('guid',)
    form = BlogAdminForm

    def save_model(self, request, obj, form, change):
        obj.body = request.POST["body"]
        return super(BlogPostAdmin, self).save_model(request, obj, form, change)