Django ModelMultipleChoiceField对象没有属性to_field_name

Question

我正在尝试为ModelForm创建自定义字段.我从ModelMultipleChoiceField扩展然后覆盖render和render_options,但是,当我只是尝试导入我的表单时,我一直得到这个异常:

AttributeError: 'ModelMultipleChoiceField' object has no attribute 'to_field_name'

我不确定我错过了什么.我甚至尝试过为我的新类添加一个to_field_name属性,但这没有用.这是我的代码:

class MultiSelect(ModelMultipleChoiceField):
def __init__(self, queryset, cache_choices=False, required=True,
             widget=None, label=None, initial=None, help_text=None, *args, **kwargs):
    super(MultiSelect, self).__init__(queryset, cache_choices, required, widget,
            label, initial, help_text, *args, **kwargs)

def render_options(self, name, choices, selected_choices):
    output = []
    i = 0
    for option_value, option_label in chain(self.choices, choices):
        checked_html = (option_value in selected_choices) and u' checked="checked"' or ''
        class_html = (i % 2 == 0) and u'even' or u'odd'
        output.append('<li class="{0}"><input type="checkbox" name="{1}" value="{2}"{3}/>{4}</li>'
                .format(class_html, name, escape(option_value), checked_html, escape(option_label)))
        i += 1

def render(self, name, value, attrs=None, choices=()):
    if value is None: value = []
    final_attrs = self.build_attrs(attrs, name=name)
    output = [u'<ul class="multiSelect">']
    options = self.render_options(name, choices, value)
    if options:
        output.append(options)
    output.append('</ul>')
    return mark_safe(u'\n'.join(output))


class RoleForm(ModelForm):
    class Meta:
        model = Role
        exclude = ('user_id',)
        widgets = {
            'permissions': MultiSelect(queryset=Permission.objects.all())
        }

每当我做一个from myapp.forms import RoleForm,我就会得到上面的错误.

我应该在课堂上添加一些我缺少的东西吗？

Answer 1

你好像在字段和小部件之间感到困惑.你继承ModelMultipleChoiceField,(顾名思义)是一个领域,而不是一个小部件.但是render并且render_options是小部件的方法,而不是字段.你已经在widgets字典中使用了你的课程.

我怀疑你的意思是创建一个小部件.您可能应该从widget类继承forms.CheckboxSelectMultiple.