如何在Django模型表单中筛选ForeignKey选项?

ForeignKey由django.forms.ModelChoiceField表示,它是一个ChoiceField,其选项是模型查询集。有关详细信息,请参阅参考资料 ModelChoiceField .

因此,为字段的 queryset 属性取决于您的表单是如何构建的。如果您构建一个显式表单,您将有直接命名的字段。

form.rate.queryset = Rate.objects.filter(company_id=the_company.id)

form.fields["rate"].queryset = ...

除了S.Lott的答案和becomingGuru在评论中提到的,还可以通过覆盖 ModelForm.__init__ 作用(这可以很容易地应用于常规表单)它可以帮助重用并保持视图功能整洁。

class ClientForm(forms.ModelForm):
    def __init__(self,company,*args,**kwargs):
        super (ClientForm,self ).__init__(*args,**kwargs) # populates the post
        self.fields['rate'].queryset = Rate.objects.filter(company=company)
        self.fields['client'].queryset = Client.objects.filter(company=company)

    class Meta:
        model = Client

def addclient(request, company_id):
        the_company = get_object_or_404(Company, id=company_id)

        if request.POST:
            form = ClientForm(the_company,request.POST)  #<-- Note the extra arg
            if form.is_valid():
                form.save()
                return HttpResponseRedirect(the_company.get_clients_url())
        else:
            form = ClientForm(the_company)

        return render_to_response('addclient.html', 
                                  {'form': form, 'the_company':the_company})

class UberClientForm(ClientForm):
    class Meta:
        model = UberClient

def view(request):
    ...
    form = UberClientForm(company)
    ...

#or even extend the existing custom init
class PITAClient(ClientForm):
    def __init__(company, *args, **args):
        super (PITAClient,self ).__init__(company,*args,**kwargs)
        self.fields['support_staff'].queryset = User.objects.exclude(user='michael')

class ClientAdminForm(forms.ModelForm):
    def __init__(self, *args, **kwargs):
        super(ClientAdminForm, self).__init__(*args, **kwargs)
        # access object through self.instance...
        self.fields['base_rate'].queryset = Rate.objects.filter(company=self.instance.company)

class ClientAdmin(admin.ModelAdmin):
    form = ClientAdminForm
    ....

您不需要在form类中指定,但可以直接在ModelAdmin中指定,因为Django已经在ModelAdmin中包含了这个内置方法(来自文档):

ModelAdmin.formfield_for_foreignkey(self, db_field, request, **kwargs)¶
'''The formfield_for_foreignkey method on a ModelAdmin allows you to 
   override the default formfield for a foreign keys field. For example, 
   to return a subset of objects for this foreign key field based on the
   user:'''

class MyModelAdmin(admin.ModelAdmin):
    def formfield_for_foreignkey(self, db_field, request, **kwargs):
        if db_field.name == "car":
            kwargs["queryset"] = Car.objects.filter(owner=request.user)
        return super(MyModelAdmin, self).formfield_for_foreignkey(db_field, request, **kwargs)

实现这一点的一种更巧妙的方法(例如,在创建用户可以访问的前端管理界面时)是将ModelAdmin子类化,然后更改下面的方法。最终的结果是用户界面只显示与他们相关的内容,同时允许您(超级用户)查看所有内容。

第三个覆盖过滤任何包含引用的查询(在示例“user”或“horcupine”(如图所示)。

最后一个覆盖过滤模型中的任何foreignkey字段,以过滤与基本queryset相同的可用选项。

通过这种方式,您可以提供一个易于管理的面向前端的管理站点,允许用户处理他们自己的对象,并且您不必记得键入我们上面提到的特定ModelAdmin筛选器。

class FrontEndAdmin(models.ModelAdmin):
    def __init__(self, model, admin_site):
        self.model = model
        self.opts = model._meta
        self.admin_site = admin_site
        super(FrontEndAdmin, self).__init__(model, admin_site)

    def get_actions(self, request):
        actions = super(FrontEndAdmin, self).get_actions(request)
        if 'delete_selected' in actions:
            del actions['delete_selected']
        return actions

阻止删除权限

    def has_delete_permission(self, request, obj=None):
        return False

    def get_queryset(self, request):
        if request.user.is_superuser:
            try:
                qs = self.model.objects.all()
            except AttributeError:
                qs = self.model._default_manager.get_queryset()
            return qs

        else:
            try:
                qs = self.model.objects.all()
            except AttributeError:
                qs = self.model._default_manager.get_queryset()

            if hasattr(self.model, ‘user’):
                return qs.filter(user=request.user)
            if hasattr(self.model, ‘porcupine’):
                return qs.filter(porcupine=request.user.porcupine)
            else:
                return qs

筛选管理网站上所有foreignkey字段的选项:

    def formfield_for_foreignkey(self, db_field, request, **kwargs):
        if request.employee.is_superuser:
            return super(FrontEndAdmin, self).formfield_for_foreignkey(db_field, request, **kwargs)

        else:
            if hasattr(db_field.rel.to, 'user'):
                kwargs["queryset"] = db_field.rel.to.objects.filter(user=request.user)
            if hasattr(db_field.rel.to, 'porcupine'):
                kwargs["queryset"] = db_field.rel.to.objects.filter(porcupine=request.user.porcupine)
            return super(ModelAdminFront, self).formfield_for_foreignkey(db_field, request, **kwargs)

要使用常规视图(如CreateView)执行此操作。。。

class AddPhotoToProject(CreateView):
    """
    a view where a user can associate a photo with a project
    """
    model = Connection
    form_class = CreateConnectionForm


    def get_context_data(self, **kwargs):
        context = super(AddPhotoToProject, self).get_context_data(**kwargs)
        context['photo'] = self.kwargs['pk']
        context['form'].fields['project'].queryset = Project.objects.for_user(self.request.user)
        return context
    def form_valid(self, form):
        pobj = Photo.objects.get(pk=self.kwargs['pk'])
        obj = form.save(commit=False)
        obj.photo = pobj
        obj.save()

        return_json = {'success': True}

        if self.request.is_ajax():

            final_response = json.dumps(return_json)
            return HttpResponse(final_response)

        else:

            messages.success(self.request, 'photo was added to project!')
            return HttpResponseRedirect(reverse('MyPhotos'))

    context['form'].fields['project'].queryset = Project.objects.for_user(self.request.user)

, read my post here

如果尚未创建表单并希望更改查询集,则可以执行以下操作:

formmodel.base_fields['myfield'].queryset = MyModel.objects.filter(...)

这在使用通用视图时非常有用!

所以,我真的试着去理解这一点,但Django似乎仍然没有让这变得非常简单。我不是那么笨,但我就是看不到任何(有点)简单的解决方案。

我发现,对于这类事情,必须覆盖管理视图通常是非常难看的,而且我发现的每个示例都不完全适用于管理视图。

这是我制作的模型中常见的情况,我发现没有明显的解决方案是令人震惊的。。。

我有以下课程:

# models.py
class Company(models.Model):
    # ...
class Contract(models.Model):
    company = models.ForeignKey(Company)
    locations = models.ManyToManyField('Location')
class Location(models.Model):
    company = models.ForeignKey(Company)

这在为公司设置管理员时会产生问题,因为它同时具有合同和位置的内联线,并且合同的位置m2m选项未根据您当前编辑的公司进行正确筛选。

简而言之,我需要一些管理选项来执行以下操作:

# admin.py
class LocationInline(admin.TabularInline):
    model = Location
class ContractInline(admin.TabularInline):
    model = Contract
class CompanyAdmin(admin.ModelAdmin):
    inlines = (ContractInline, LocationInline)
    inline_filter = dict(Location__company='self')

归根结底,我不在乎过滤过程是放在基本CompanyAdmin上,还是放在收缩行上。(将其放在内联上更有意义,但这样很难将基本契约引用为“self”。)

更公开的方法是在管理类中调用get_表单。它也适用于非数据库字段。例如,我在表单上有一个名为“_terminal_list”的字段,可在特殊情况下用于从get_list(请求)中选择几个终端项,然后根据请求进行过滤。用户:

class ChangeKeyValueForm(forms.ModelForm):  
    _terminal_list = forms.ModelMultipleChoiceField( 
queryset=Terminal.objects.all() )

    class Meta:
        model = ChangeKeyValue
        fields = ['_terminal_list', 'param_path', 'param_value', 'scheduled_time',  ] 

class ChangeKeyValueAdmin(admin.ModelAdmin):
    form = ChangeKeyValueForm
    list_display = ('terminal','task_list', 'plugin','last_update_time')
    list_per_page =16

    def get_form(self, request, obj = None, **kwargs):
        form = super(ChangeKeyValueAdmin, self).get_form(request, **kwargs)
        qs, filterargs = Terminal.get_list(request)
        form.base_fields['_terminal_list'].queryset = qs
        return form

根据Django文档,您可以使用 __init__

https://docs.djangoproject.com/en/3.1/ref/contrib/admin/#django.contrib.admin.ModelAdmin.formfield_for_foreignkey

class CountryAdminForm(forms.ModelForm):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.fields['capital'].queryset = self.instance.cities.all()

class CountryAdmin(admin.ModelAdmin):
    form = CountryAdminForm