[英]Django REST API - Joining multiple tables in a query
我的目标是获取所有 EmployeeQuestions,这样员工就有一个具有给定 id (request.user.pk) 的雇主。 更正式地说,我想获取所有 EmployeeQuestions ,其中 question 有一个课程,其中雇主 ID 是给定的 ID。
我希望这是有道理的。 基本上作为雇主,我想检索所有员工的所有问题进度。
我以为我做了正确的查询,但它只返回所有 EmployeeQuestions:
EmployeeQuestion.objects.filter(question__in=CourseQuestion.objects.filter(course__in=Course.objects.filter(employer_id=request.user.pk)))
这里有任何 Django 查询天才可以帮助我吗? :)
看法
class EmployeeQuestionByEmployerId(viewsets.ModelViewSet):
queryset = EmployeeQuestion.objects.all()
serializer_class = EmployeeQuestionSerializer
def list(self, request):
queryset = EmployeeQuestion.objects.all()
if request.query_params:
queryset = EmployeeQuestion.objects.filter(question__in=CourseQuestion.objects.filter(course__in=Course.objects.filter(employer_id=request.user.pk)))
serializer = EmployeeQuestionSerializer(queryset, many=True)
return Response(serializer.data)
楷模
class CustomUser(AbstractBaseUser):
username = ...
employer = models.ForeignKey("self", blank=True, null=True, on_delete=models.CASCADE)
class Course(models.Model):
employer_id = models.ForeignKey(CustomUser, on_delete=models.CASCADE, null=True)
title = models.CharField(max_length=255, blank=False, null=False)
class Question(models.Model):
course = models.ForeignKey(Course, on_delete=models.CASCADE, null=False)
question = models.CharField(max_length=255, blank=False, null=False)
question_type = models.CharField(max_length=255, blank=False, null=False) # mult/ord/open
class EmployeeQuestion(models.Model):
employee = models.ForeignKey(CustomUser, on_delete=models.CASCADE, null=True)
question = models.ForeignKey(CourseQuestion, on_delete=models.CASCADE, null=False)
passed = models.BooleanField(default=False)
您可以在双下划线的帮助下过滤外键模型的属性,如下所示:
EmployeeQuestion.objects.filter(question__course__employer_id=request.user.pk)
它将在数据库级别内部自动执行内部联接。
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