How to filter multiple fields using Django-filter?

Question

I want to retrieve data filtered by user and category.

I'm using Django Rest Framework.

models.py

class Practice(models.Model):
    practice_id = models.BigAutoField(primary_key=True)
    user = models.ForeignKey('User', models.DO_NOTHING, default=None)
    subcategory = models.ForeignKey('Subcategory', models.DO_NOTHING, default=None)
    score = models.SmallIntegerField(null=True)

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

class User(models.Model):
    user_id = models.BigAutoField(primary_key=True)
    fullname = models.CharField(max_length=50)

    def __str__(self):
        return self.fullname

class Subcategory(models.Model):
    subcategory_id = models.BigAutoField(primary_key=True)
    category = models.CharField(max_length=30)

    def __str__(self):
        return f"{ self.category }"

serializers.py

class PracticeSerializer(serializers.ModelSerializer):
    subcategory = SubcategorySerializer()

    class Meta:
        model = Practice
        fields = ('practice_id',
                  'user',
                  'subcategory',
                  'score',
                  )

views.py

@api_view(['GET'])
def practiceFilter_User(request):
    if request.method == 'GET':
        exercises = Practice.objects.all()
        
        user = request.GET.get('user', None)
        if user is not None:
            practice_filtered = exercises.filter(user__user_id__icontains=user)

        exercises_serializer = PracticeSerializer(practice_filtered, many=True)
        return JsonResponse(exercises_serializer.data, safe=False)

urls.py

urlpatterns = [ 
        url(r'^api/practice-filter-user$', views.practiceFilter_User),
]

In my database I have 3 practice data as below :

[
  {
    practice_id: 1,
    user: 1,
    subcategory: {
      subcategory_id: 1,
      category: "Math",
    },
    score: 7,
  },
  {
    practice_id: 2,
    user: 1,
    subcategory: {
      subcategory_id: 1,
      category: "Math",
    },
    score: 8,
  },
  {
    practice_id: 3,
    user: 1,
    subcategory: {
      subcategory_id: 2,
      category: "History",
    },
    score: 9,
  }
]

If the above code is executed to get practice data by user id = 1, the result is as below :

api/practice-filter-user?user=1

[
  {
    practice_id: 1,
    user: 1,
    subcategory: {
      subcategory_id: 1,
      category: "Math",
    },
    score: 7,
  },
  {
    practice_id: 2,
    user: 1,
    subcategory: {
      subcategory_id: 1,
      category: "Math",
    },
    score: 8,
  },
  {
    practice_id: 3,
    user: 1,
    subcategory: {
      subcategory_id: 2,
      category: "History",
    },
    score: 9,
  }
]

I want to retrieve data filtered by all user with id 1 and all Math category like below :

api/practice-filter-subcategory-user?user=1&category=Math

[
  {
    practice_id: 1,
    user: 1,
    subcategory: {
      subcategory_id: 1,
      category: "Math",
    },
    score: 7,
  },
  {
    practice_id: 2,
    user: 1,
    subcategory: {
      subcategory_id: 1,
      category: "Math",
    },
    score: 8,
  }
]

The results as above are what I want when retrieving practice data that is filtered by user and category.

I've tried using django-filter on this link but the error appears.

I added a class to views.py

class practiceFilter_Subcategory_User(generics.ListAPIView):
    queryset = Practice.objects.all()
    serializer_class = PracticeSerializer
    filter_fields = ('user', 'category')

I added url to urls.py

urlpatterns = [ 
        url(r'^api/practice-filter-subcategory-user$', views.practiceFilter_Subcategory_User),
]

And I try to retrieve data filtered by all user with id 1 and all Math category like below :

api/practice-filter-subcategory-user?user=1&category=Math

But I failed and got the error as above.

Is it possible to filter all user by id 1 and all Math category?

Update the Traceback error I got :

Environment:


Request Method: GET
Request URL: http://192.168.1.2:8080/api/practice-filter-subcategory-user?user_id=1&category=Math

Django Version: 3.2.5
Python Version: 3.7.9
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'rest_framework',
 'rest_framework_bulk',
 'yasn.apps.yasnConfig',
 'corsheaders',
 'django_filters']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'corsheaders.middleware.CorsMiddleware',
 'django.middleware.common.CommonMiddleware']



Traceback (most recent call last):
  File "C:\Users\Me\Documents\Python\env\lib\site-packages\django\core\handlers\exception.py", line 47, in inner
    response = get_response(request)
  File "C:\Users\Me\Documents\Python\env\lib\site-packages\django\core\handlers\base.py", line 181, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)

Exception Type: TypeError at /api/practice-filter-subcategory-user
Exception Value: __init__() takes 1 positional argument but 2 were given

Update urls.py :

from django.conf.urls import url 
from yasn import views 
 
urlpatterns = [ 
        url(r'^api/practice-filter-user$', views.practiceFilter_User),
        url(r'^api/practice-filter-subcategory-user$', views.practiceFilter_Subcategory_User),
]

Verify your url in the get_queryset() the parameters retrieved are user_id, category your url contains user and category. Try to correct it and let us know — Rvector
– Rvector, Commented Sep 5, 2021 at 21:53
I've tried changing my url parameter from user to user_id and running the program but still showing the same error, I've updated the error in the question above using user_id in the url. — Aras121
– Aras121, Commented Sep 5, 2021 at 22:39
Sorry... You need always call the .as_view() method on class based view in Django. I have updated the url pattern in the answer. — Rvector
– Rvector, Commented Sep 6, 2021 at 9:42

Rvector · Accepted Answer · 2021-09-06 09:40:10Z

2

Yes it is possible to filter with many parameters. Django Rest Framework provide us many options to achieve this goal. I'll show you one of them : Filtering against query parameters. You can override .get_queryset() of your class based view to deal with URLs such as api/practice-filter-subcategory-user?user=1&category=Math

class practiceFilter_Subcategory_User(generics.ListAPIView):
    serializer_class = PracticeSerializer

    def get_queryset(self):
        # If they are no parameters return all objects
        queryset = Practice.objects.all()
        # Retrieve the query parameters in the url
        user_id = self.request.query_params.get('user_id')
        category = self.request.query_params.get('category')
        # If they are present
        if user_id is not None and category is not None:
            practice_filtered = exercises.filter(user__user_id=user_id)
            # Filter by category, you can chain filter of course
            practice_filtered = practice_filtered.filter(subcategory__category=category)
            queryset = practice_filtered
        return queryset

Here is the DRF documentation

VERY IMPORTANT : You need call .as_view() on your url views like this :

from django.conf.urls import url 
from yasn import views 

urlpatterns = [ 
    url(r'^api/practice-filter-user$', views.practiceFilter_User.as_view()),
    url(r'^api/practice-filter-subcategory-user$', views.practiceFilter_Subcategory_User.as_view()),
]

edited Sep 6, 2021 at 9:40

answered Sep 5, 2021 at 16:39

Rvector

2,4721 gold badge11 silver badges17 bronze badges

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

1 Comment

Aras121 Over a year ago

Thanks for the response, i have tried to follow your instructions but i get an error. I included the error at the end of my question above.

Collectives™ on Stack Overflow

How to filter multiple fields using Django-filter?

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related