Django管理 - “ManyToManyField”对象有“到”

Question

TL无属性;博士

的Django抛出AttributeError当我试图渲染管理类使用ManyToMany关系，通过自定义表单fields或fieldsets属性，除了form属性：

AttributeError: 'ManyToManyField' object has no attribute 'through'

---

型号：

我有两个模型绑定与ManyToMany关系：

class Project(models.Model): 
    title = models.CharField(max_length=200, unique=True) 

class Centre(models.Model): 
    projects = models.ManyToManyField(
     Project, blank=True, related_name='centres', 
    ) 

表：

而且，我创建了一个自定义窗体为Project模型添加FilteredSelectMultiple领域Centre：

class ProjectAdminForm(forms.ModelForm): 
    centres = forms.ModelMultipleChoiceField(
     Centre.objects.all(), 
     widget=admin.widgets.FilteredSelectMultiple('Centres', False), 
     required=False, 
    ) 

    def __init__(self, *args, **kwargs): 
     super(ProjectAdminForm, self).__init__(*args, **kwargs) 
     if self.instance.pk: 
      self.initial['centres'] = self.instance.centres.values_list(
       'pk', flat=True 
      ) 

    def save(self, *args, **kwargs): 
     instance = super(ProjectAdminForm, self).save(*args, **kwargs) 
     if instance.pk: 
      instance.centres.clear() 
      instance.centres.add(*self.cleaned_data['centres']) 
     return instance 

Admin：

的事情是，当我定义管理类这样的：

@admin.register(Project, site=admin_site) 
class ProjectAdmin(admin.ModelAdmin): 
    form = ProjectAdminForm 

它工作正常，并呈现为title和centres领域一个正确的形式。

问题

但是，如果我定义字段，例如：

@admin.register(Project, site=admin_site) 
class ProjectAdmin(admin.ModelAdmin): 
    form = ProjectAdminForm 
    fields = ('title', 'centres',) 

这将引发AttributeError：

AttributeError: 'ManyToManyField' object has no attribute 'through'

我试过在Project设置上models.ManyToManyFieldthrough属性模型，定义中介ProjectCentresModel，但我仍然无法理解Django内部发生了什么，我应该调整以使其工作。

---

回溯：

Unhandled exception in thread started by <function check_errors.<locals>.wrapper at 0x7f88ac6e5bf8> 
Traceback (most recent call last): 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/utils/autoreload.py", line 226, in wrapper 
    fn(*args, **kwargs) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/core/management/commands/runserver.py", line 113, in inner_run 
    autoreload.raise_last_exception() 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/utils/autoreload.py", line 249, in raise_last_exception 
    six.reraise(*_exception) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/utils/six.py", line 685, in reraise 
    raise value.with_traceback(tb) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/utils/autoreload.py", line 226, in wrapper 
    fn(*args, **kwargs) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/__init__.py", line 27, in setup 
    apps.populate(settings.INSTALLED_APPS) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/apps/registry.py", line 115, in populate 
    app_config.ready() 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/contrib/admin/apps.py", line 23, in ready 
    self.module.autodiscover() 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/contrib/admin/__init__.py", line 26, in autodiscover 
    autodiscover_modules('admin', register_to=site) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/utils/module_loading.py", line 50, in autodiscover_modules 
    import_module('%s.%s' % (app_config.name, module_to_search)) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/importlib/__init__.py", line 126, in import_module 
    return _bootstrap._gcd_import(name[level:], package, level) 
    File "<frozen importlib._bootstrap>", line 986, in _gcd_import 
    File "<frozen importlib._bootstrap>", line 969, in _find_and_load 
    File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked 
    File "<frozen importlib._bootstrap>", line 673, in _load_unlocked 
    File "<frozen importlib._bootstrap_external>", line 665, in exec_module 
    File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed 
    File "/media/kidbinary/Data/web/PYTHON/work_project/work/website/admin.py", line 165, in <module> 
    class ProjectAdmin(DefaultOrderingModelAdmin): 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/contrib/admin/decorators.py", line 28, in _model_admin_wrapper 
    admin_site.register(models, admin_class=admin_class) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/contrib/admin/sites.py", line 110, in register 
    system_check_errors.extend(admin_obj.check()) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/contrib/admin/options.py", line 117, in check 
    return self.checks_class().check(self, **kwargs) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/contrib/admin/checks.py", line 515, in check 
    errors = super(ModelAdminChecks, self).check(admin_obj) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/contrib/admin/checks.py", line 71, in check 
    errors.extend(self._check_fieldsets(admin_obj)) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/contrib/admin/checks.py", line 155, in _check_fieldsets 
    for index, fieldset in enumerate(obj.fieldsets) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/contrib/admin/checks.py", line 155, in <listcomp> 
    for index, fieldset in enumerate(obj.fieldsets) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/contrib/admin/checks.py", line 190, in _check_fieldsets_item 
    for fieldset_fields in fieldset[1]['fields'] 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/contrib/admin/checks.py", line 190, in <listcomp> 
    for fieldset_fields in fieldset[1]['fields'] 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/contrib/admin/checks.py", line 204, in _check_field_spec 
    return self._check_field_spec_item(obj, model, fields, label) 
    File "/media/kidbinary/Data/web/PYTHON/.virtualenvs/work/lib/python3.5/site-packages/django/contrib/admin/checks.py", line 220, in _check_field_spec_item 
    if field.many_to_many and not field.remote_field.through._meta.auto_created: 
AttributeError: 'ManyToManyField' object has no attribute 'through' 

Answer 1

class ProjectAdmin(admin.ModelAdmin): 
    model = Project 
    form = ProjectAdminForm 
    fields = ('title', 'centres',) 


class CentreAdmin(admin.ModelAdmin): 
    model = Centre 
    list_display = ['id', 'get_projects'] 

    def get_projects(self, obj): 
     #lists all the projects under a center without having to use inlines 
     return "\n".join([proj.title for proj in obj.projects.all()]) 

老实说，我不能说为什么它被扔的错误，将模型只是一个猜测。我检查了django中的错误源文件，但无法真正理解那里发生了什么。