Django rest框架-使用SerializerMethodField和ModelSerializer

Question

我有以下模型。

型号.py

class Language(models.Model):
name = models.CharField(max_length=255, unique=True)
class Subject(models.Model):
name = models.CharField(max_length=255, unique=True)
class Term(models.Model):
subject = models.ForeignKey(Subject, on_delete=models.CASCADE)
language = models.ForeignKey(Language, on_delete=models.CASCADE)
name = models.CharField(max_length=255)
definition = models.TextField()
image = models.ImageField(default='', blank=True)

我想写一个序列化程序，它将返回一个主题列表。每个主题都有一个术语字段，其中包含"无"或单个对象，具体取决于condition。

serializers.py

class TermSerializer(serializers.ModelSerializer):
language = serializers.CharField(source='language.name')
def to_representation(self, data):
data = data.get(language=self.context['language'])
return super(TermSerializer, self).to_representation(data)
class Meta:
model = Term
fields = ('id', 'language', 'name', 'definition', 'image')
class FilteredSubjectSerializer(serializers.ListSerializer):
def to_representation(self, data):
if self.context['condition']:
terms = Term.objects.filter(language=self.context['language'])
data = data.filter(term__in=terms)
return super(FilteredSubjectSerializer, self).to_representation(data)
class SubjectSerializer(serializers.ModelSerializer):
term = serializers.SerializerMethodField()
def get_term(self, term):
if self.context['condition']:
return TermSerializer(many=False, source='term_set').data
return None
class Meta:
model = Term
list_serializer_class = FilteredSubjectSerializer
fields = ('id', 'name', 'definition', 'image', 'term')

问题是，当condition == True时，ViewSet返回不正确的数据。术语中的所有字段都有一个默认值。

如果我这样写SubjectSerializer，效果很好：

class SubjectSerializer(serializers.ModelSerializer):
term = serializers.TermSerializer(many=False, source='term_set')
class Meta:
model = Term
list_serializer_class = FilteredSubjectSerializer
fields = ('id', 'name', 'definition', 'image', 'term')

但是condition == False不起作用的情况。

Answer 1

尝试将实例和上下文传递给序列化程序。像这样：

def get_term(self, instance):
if self.context['condition']:
return TermSerializer(many=False, source='term_set', instance=instance, context=self.context).data
return None