Is there a way to add custom data into ListAPIView in django rest framework-CodePudding

So I've built an API for movies dataset which contain following structure:

Models.py

class Directors(models.Model):
    id = models.IntegerField(primary_key=True)
    first_name = models.CharField(max_length=100, blank=True, null=True)
    last_name = models.CharField(max_length=100, blank=True, null=True)

    class Meta:
        db_table = 'directors'
        ordering = ['-id']

class Movies(models.Model):
    id = models.IntegerField(primary_key=True)
    name = models.CharField(max_length=100, blank=True, null=True)
    year = models.IntegerField(blank=True, null=True)
    rank = models.FloatField(blank=True, null=True)

    class Meta:
        db_table = 'movies'       
        ordering = ['-id']

class Actors(models.Model):
    id = models.IntegerField(primary_key=True)
    first_name = models.CharField(max_length=100, blank=True, null=True)
    last_name = models.CharField(max_length=100, blank=True, null=True)
    gender = models.CharField(max_length=20, blank=True, null=True)

    class Meta:
        db_table = 'actors'       
        ordering = ['-id']

class DirectorsGenres(models.Model):
    director = models.ForeignKey(Directors,on_delete=models.CASCADE,related_name='directors_genres')
    genre = models.CharField(max_length=100, blank=True, null=True)
    prob = models.FloatField(blank=True, null=True)    

    class Meta:
        db_table = 'directors_genres'       
        ordering = ['-director']

class MoviesDirectors(models.Model):
    director = models.ForeignKey(Directors,on_delete=models.CASCADE,related_name='movies_directors')
    movie = models.ForeignKey(Movies,on_delete=models.CASCADE,related_name='movies_directors')
    class Meta:
        db_table = 'movies_directors'       
        ordering = ['-director']
        


class MoviesGenres(models.Model):
    movie = models.ForeignKey(Movies,on_delete=models.CASCADE,related_name='movies_genres')
    genre = models.CharField(max_length=100, blank=True, null=True)    

    class Meta:
        db_table = 'movies_genres'        
        ordering = ['-movie']


class Roles(models.Model):
    actor = models.ForeignKey(Actors,on_delete=models.CASCADE,related_name='roles')
    movie = models.ForeignKey(Movies,on_delete=models.CASCADE,related_name='roles')    
    role = models.CharField(max_length=100, blank=True, null=True)    

    class Meta:
        db_table = 'roles'        
        ordering = ['-actor']

urls.py

from django.urls import path, include
from . import views
from api.views import getMovies, getGenres, getActors

urlpatterns = [ 
    path('', views.getRoutes),    
    path('movies/', getMovies.as_view(), name='movies'),    
    path('movies/genres/', getGenres.as_view(), name='genres'),
    path('actor_stats/<pk>', getActors.as_view(), name='actor_stats'),    
]

serializer.py

from rest_framework import serializers
from movies.models import *

class MoviesSerializer(serializers.ModelSerializer):
    class Meta:
        model = Movies
        fields = '__all__'

class DirectorsSerializer(serializers.ModelSerializer):
    class Meta:
        model = Directors
        fields = '__all__'

class ActorsSerializer(serializers.ModelSerializer):
    class Meta:
        model = Actors
        fields = '__all__'

class DirectorsGenresSerializer(serializers.ModelSerializer):
    class Meta:
        model = DirectorsGenres
        fields = '__all__'

class MoviesDirectorsSerializer(serializers.ModelSerializer):
    movie = MoviesSerializer(many = False)
    director = DirectorsSerializer(many = False)
    class Meta:
        model = MoviesDirectors
        fields = '__all__'

class MoviesGenresSerializer(serializers.ModelSerializer):
    movie = MoviesSerializer(many = False)
    class Meta:
        model = MoviesGenres
        fields = '__all__'

class RolesSerializer(serializers.ModelSerializer):
    movie = MoviesSerializer(many = False)
    actor = ActorsSerializer(many = False)
    class Meta:
        model = Roles
        fields = '__all__'

views.py

class getMovies(ListAPIView):
    directors = Directors.objects.all()  
    queryset = MoviesDirectors.objects.filter(director__in=directors)
    serializer_class = MoviesDirectorsSerializer
    pagination_class = CustomPagination
    filter_backends = [DjangoFilterBackend]
    filterset_fields = ['director__first_name', 'director__last_name']

class getGenres(ListAPIView):
    movies = Movies.objects.all()  
    queryset = MoviesGenres.objects.filter(movie__in=movies).order_by('-genre')
    serializer_class = MoviesGenresSerializer
    pagination_class = CustomPagination
    filter_backends = [DjangoFilterBackend]
    filterset_fields = ['genre']

class getActors(ListAPIView):
    queryset = Roles.objects.all()
    serializer_class = RolesSerializer
    pagination_class = CustomPagination

    def get_queryset(self):
        return super().get_queryset().filter(
            actor_id=self.kwargs['pk']
        )

Now I want to count number of movies by genre that actor with specific pk played in getActors class. Like the number of movies by genre that actor participated in. E.g. Drama: 2, Horror: 3 Right now I am getting the overall count of movies count: 2:

GET /api/actor_stats/17


HTTP 200 OK
Allow: GET, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "count": 2,
    "next": null,
    "previous": null,
    "results": [
        {
            "id": 800480,
            "movie": {
                "id": 105231,
                "name": "Everybody's Business",
                "year": 1993,
                "rank": null
            },
            "actor": {
                "id": 17,
                "first_name": "Luis Roberto",
                "last_name": "Formiga",
                "gender": "M"
            },
            "role": "Grandfather"
        },
        {
            "id": 800481,
            "movie": {
                "id": 242453,
                "name": "OP Pro 88 - Barra Rio",
                "year": 1988,
                "rank": null
            },
            "actor": {
                "id": 17,
                "first_name": "Luis Roberto",
                "last_name": "Formiga",
                "gender": "M"
            },
            "role": "Himself"
        }
    ]
}

What is the optimized way of achieving the following:

number_of_movies_by_genre
Drama: 2
Horror: 3

after count?

CodePudding user response：

There many ways to implement this route, it depends on many criteria and how much it will be used .

i think a correct way is to create a dedicated model that would store actor stats with a one to one relation to actor and recompute the value each time a movie is added. But If you add movie often it could slow down your database.

You can also accept to have some outdated data for a while and update the table regularly using a background job and maybe using custom sql query that will ensure you better performance (bulk update).

CodePudding user response：

I would start from your model, you have genres defined as a CharField in two of your models. By not isolating them anywhere, you need to look in both tables for all types of genres. If do not, then you are just supposing that all the genres you have in one table is also on the other one, which could not be true.

Also, querying string fields is not very efficient when in comparison to a int PK, so from the point of view of scaling this is bad. (Of course, i am saying that in general, as a good practice and not focused specifically in movie genres)

Your best option would be to have either a Genre Model or a choice field, where you define all possible genres.

As for the counting, you would do that inside your serializer class, by using a serializermethodfield.