我有三种模式：LineType，Service，DomainName，Record，它们之间有m2m或foreignkey关系。这是代码：
class LineType(models.Model):
linename = models.CharField(max_length=30,primary_key=True)
def __unicode__(self):
return self.linename
class Service(models.Model):
servicename = models.CharField(max_length=30,primary_key=True)
price = models.DecimalField(max_digits=8, decimal_places=2)
line = models.ManyToManyField(LineType)
def __unicode__(self):
return self.servicename
class DomainName(models.Model):
domainname = models.CharField(max_length=30,primary_key=True)
user = models.ForeignKey(SiteProfile)
service = models.ForeignKey(Service)
def __str__(self):
return self.domainname
class Record(models.Model):
TYPE_CHOICES = (
('A','A'),
('CNAME','CNAME'),
('MX','MX'),
)
domainname = models.ForeignKey(DomainName)
def get_line(self):
domain = DomainName.objects.get(pk=self.domainname_id)
service = Service.objects.get(pk=domain.service_id)
lines = service.line.all()
choices = []
for x in lines:
choices.append((x.linename,x.linename))
return choices
host = models.CharField(max_length=30)
type = models.CharField(max_length=5,choices=TYPE_CHOICES,default='A')
line = models.ForeignKey(LineType)
destaddress = models.CharField(max_length=30)
让我介绍一下这个模型。每个DomainName只能有一个其他DomainNames可以拥有的服务。每个DomainName都有多个记录。服务定义可应用于记录的LineType。
我使用Django admin来管理这些模型，但Record中“line”的选择都是LineType对象。所以问题是如何根据它的父级的“服务”过滤RecordType的LineType（DomainName） ）。
答案 0 :(得分：0)
取决于您的确切要求和您的Django版本，答案可能是设置limit_choices_to attribute of the foreign key，或自定义ModelAdmin表单：
limit_choices_to 只需将行选项限制为匹配linename == 'foo'
class Record(models.Model):
# ...
line = models.ForeignKey(LineType, limit_choices_to={'linename': 'foo'}))
form 如果在实例化表单时存在实例，我们可以选择它的域的服务行作为查询集选项
class RecordAdminForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
super(RecordAdminForm, self).__init__(*args, **kwargs)
# access object through self.instance...
if self.instance:
valid_lines = self.instance.domainname.service.line.objects.all()
self.fields['line'].queryset = valid_lines
class RecordAdmin(admin.ModelAdmin):
form = RecordAdminForm
# ...