CODEWITHSUNDEEP
pythondjangoapirest
Dahn Ng
Dahn Ng

Reputation: 11

get() returned more than one Modules -- it returned 2! (REST API - Django)

Here are my models:

class Modules(models.Model):
    module_name = models.CharField(max_length=50)
    module_duration = models.IntegerField()
    class_room = models.IntegerField()
    def __str__(self):
        return self.module_name
class Students(models.Model):
    name = models.CharField(max_length=50)
    age = models.IntegerField()
    grade = models.IntegerField()
    modules = models.ManyToManyField(Modules)
    def __str__(self):
        return self.name

Here are my views:

class StudentsViewSet(viewsets.ModelViewSet):
    serializer_class = StudentsSerializer
    def get_queryset(self):
        student = Students.objects.all()
        return student
    def create(self,request,*args, **kwargs):
        data = request.data
        new_student = Students.objects.create(name=data["name"], age=data['age'], grade=data["grade"])
        new_student.save()
        for module in data["modules"]:
            module_obj = Modules.objects.get(module_name=module["module_name"])
            new_student.modules.add(module_obj)
        serializer = StudentsSerializer(new_student)
        return Response(serializer.data)
class ModulesViewSet(viewsets.ModelViewSet):
    serializer_class = ModudesSerializer
    def get_queryset(self):
        module = Modules.objects.all()
        return module    ```

When I post this:

*{
    "name": "steve",
    "age": 16,
    "grade": 10,
    "modules": [
        {
            "module_name": "math"
        },
        {
            "module_name": "physics"
        }
    ]
}*

It says:

MultipleObjectsReturned at /app_Five/student/
get() returned more than one Modules -- it returned 2!

I understand that get() only gets one element. But I think in thefor loop above, only one module_name exists for each loop. So each time the get() executes, there's only one result for it to get. Can anyone tell me what I did wrong there?

Upvotes: 0

Views: 79

Answers (1)

Asgeer
Asgeer

Reputation: 176

It seems that you expect the module name to be unique. You probably have multiple Modules entries in the database with the same module_name.

To ensure unique names when creating Module entries you could change the Modules model to enforce this:

class Modules(models.Model):
    module_name = models.CharField(unique=True, max_length=50)
    module_duration = models.IntegerField()
...

Upvotes: 1

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