How to return data from two different tables in django?

Question

I have two models in my models.py. I need to return a json response which includes data from two tables. How should my view and serializer look like?

class Device(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    device_name = models.CharField(max_length=200, null=True, blank=True )
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return str(self.device_name)

class StatusActivity(models.Model):
    OFFLINE = 1
    ONLINE = 2
    STATUS = (
        (OFFLINE, ('Offline')),
        (ONLINE, ('Online')),
    )
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    device_id = models.ForeignKey(Device, related_name='StatusActivity', on_delete=models.CASCADE)
    changed_to = models.PositiveSmallIntegerField(choices=STATUS)
    modified_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return str(self.device_id)

Expected Response:

 {
    "device_id":"",
    "device_name":"",
    "changed_to":"",
    "modified_at":"",
  }

UPDATE: I set my views.py and serializer.py as below. I am checking

Serializer.py

class DeviceSerializer(serializers.ModelSerializer):
    class Meta:
        model = Device
        fields = '__all__'

class StatusActivitySerializer(serializers.ModelSerializer):

    class Meta:
        model = StatusActivity
        fields = '__all__'

class ListSerializer(serializers.Serializer):
    # devices = DeviceSerializer(many=True)
    # activities = StatusActivitySerializer(many=True)

    class Meta:
        model = [Device, StatusActivity]
        fields = ['device_id', 'device_name', 'changed_to', 'modified_at']

Views.py

class DeviceListView(generics.ListAPIView):
    queryset = Device.objects.all()
    serializer_class = ListSerializer

class StatusActivityListView(generics.ListAPIView):
    queryset = StatusActivity.objects.all()
    serializer_class = StatusActivitySerializer

Why do you have 2 views? If you want one response, you should have only one view. — dirkgroten
– dirkgroten, Commented Nov 30, 2019 at 16:49
Okey, and how it should look like? I still can not retrieve a data like a describe in my question above. Can you point how can i do that? @dirkgroten — erondem
– erondem, Commented Nov 30, 2019 at 16:51
First, are you fetching a Device or a StatusActivity (i.e. which pk/id is passed in your url)? Create the serializer for that model, then add the fields from the other model manually by specifying the source. — dirkgroten
– dirkgroten, Commented Nov 30, 2019 at 17:10

funnydman · Accepted Answer · 2019-11-30 17:15:32Z

3

Actually you don't need to have two separated views for this, because you can easily serialize relations from one serializer class. Take a look at this useful answer: How do I include related model fields using Django Rest Framework?

For your case you can write something like this:

class StatusActivitySerializer(serializers.ModelSerializer):
    device_name = serializers.CharField(source='device_id.device_name')

    class Meta:
        model = StatusActivity
        fields = ('changed_to', 'modified_at', 'device_id', 'device_name')

Something that worth to note:

it's a good idea for ForeignKey field use device name instead of device_id;
related_name arg should have a name for reverse access. Keep it meaningful, e.g. status_activities is a good choice.

edited Nov 30, 2019 at 17:15

answered Nov 30, 2019 at 17:03

funnydman

11.8k4 gold badges51 silver badges67 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

erondem Over a year ago

Thanks a lot. It gives me what I need. But I didn't understand your first point. Why should I use device_name instead of device_id? @funnydman

funnydman Over a year ago

@erondem Ah, actually there is misunderstanding I'm specially highting device and device_id to make the difference. You should use device instead of device_id because Django automatically appends _id postfix, so in your case you'll have device_id_id field and more likely that is not what you want.

suhailvs · Accepted Answer · 2019-11-30 16:15:52Z

0

filter the status activity. you can refer the foreignkey. eg:

items = []
for statusact in StatusActivity.objects.all():
    items.append({
        "device_id":statusact.device_id.id,
        "device_name":statusact.device_id.device_name,
        "changed_to":statusact.changed_to,
        "modified_at":statusact.modified_at,
    })

answered Nov 30, 2019 at 16:15

suhailvs

21.9k15 gold badges104 silver badges104 bronze badges

1 Comment

erondem Over a year ago

I have 3 entry in db but it respond me this [ {}, {}, {} ]

Collectives™ on Stack Overflow

How to return data from two different tables in django?

2 Answers 2

2 Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related