How to join two models in django-rest-framework

Question

Let say i have two models:

level:

id
file_number
status


level_process:

process_ptr_id
level_id

I want to combine both of my table above to display it in one API using django-rest-framework.. I'm looking for the example on the internet and i cannot find it...by the way i'm using python 2.7 , django 1.10.5 and djangorestframework 3.6.2

serializer.py

class LevelSerializer(serializers.HyperlinkedModelSerializer):
    id = serializers.ReadOnlyField()
    class Meta:
        model = Level
        fields = ('__all__')

class LevelProcessSerializer(serializers.ModelSerializer):
    level = LevelSerializer(read_only=True)

    class Meta:
        model = LevelProcess
        fields = ('__all__')

views.py

class ViewLevelProcessViewSet(viewsets.ModelViewSet):
    processes = LevelProcess.objects.all()
    serializer_class = LevelProcessSerializer(processes, many=True)

Jahongir Rahmonov · Accepted Answer · 2017-04-04 09:35:34Z

22

Try the following. Create serializer for your Level model:

class LevelSerializer(serializers.ModelSerializer):
    class Meta:
        model = Level

Then, inside LevelProcessSerializer, include LevelSerializer like this:

class LevelProcessSerializer(serializers.ModelSerializer):
    level = LevelSerializer(read_only=True)

    class Meta:
        model = LevelProcess

Usage in your ModelViewset:

class ViewLevelProcessViewSet(viewsets.ModelViewSet):
    queryset = LevelProcess.objects.all() 
    serializer_class = LevelProcessSerializer

This way, your json will look something like this:

{
   "id": 1,
   "level": {
      "id": 3,
      "status": "red"
   }
}

Hope this helps!

edited Apr 4, 2017 at 9:35

answered Apr 4, 2017 at 4:21

Jahongir Rahmonov

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8 Comments

Jahongir Rahmonov Over a year ago

@uetoaya this is assuming that level inside your LevelProcess is a foreign key. If not, let me know

MunirohMansoor Over a year ago

yes.. level_id is a foreign key in LevelProcess

MunirohMansoor Over a year ago

what about queryset in myviews?

MunirohMansoor Over a year ago

i try your code and got this error could not automatically determine the name from the viewset, as it does not have a '.queryset' attribute.

Jahongir Rahmonov Over a year ago

@uetoaya see usage in the answer. The error you got is because of something else, I think. Please, paste your code and I will try to help

|

0sVoid · Accepted Answer · 2022-08-16 09:37:23Z

0

class LevelSerializer(serializers.ModelSerializer):
    class Meta:
        model = Level
        fields="__all__"

class LevelProcessSerializer(serializers.ModelSerializer):
    level = LevelSerializer(read_only=True)

class Meta:
    model = LevelProcess
    fields= "__all__"

edited Aug 16, 2022 at 9:37

0sVoid

2,7881 gold badge13 silver badges26 bronze badges

answered Aug 12, 2022 at 10:09

Gyanu Chauhan

11 bronze badge

Comments

Ashraful · Accepted Answer · 2017-11-14 06:10:03Z

-3

Don't try to "join" tables. This isn't SQL.

I am assuming your model look like Following,

class Level(models.Model):
    .......

class LevelProcess(models.Model):
    level = models.ForeignKey(Level)

Now, let's walk for query,

l = Level.objects.filter(id=level_id).first()
lp = l.level_process_set.all()

This is how we do in Django ORM.

edited Nov 14, 2017 at 6:10

answered Apr 4, 2017 at 4:10

Ashraful

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1 Comment

JTW Over a year ago

Doesn't this result in multiple queries for each related LevelProcess? How is that preferable? It is ultimately SQL, you can't just pretend there's not a database engine behind this thing...

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