feat: Add like endpoint for promo codes

RandomProgramm3r · RandomProgramm3r · commit 27e6633a384b · 2025-05-13T23:54:59.000+03:00
Add two new idempotent endpoints to manage likes on promo codes:

- **POST** `/user/promo/{id}/like` – add a like to the specified promo code
- **DELETE** `/user/promo/{id}/like` – remove a like from the specified promo code

Both operations return HTTP 200 and do not modify the like count if:
1. The user has already liked the promo code (on POST), or
2. The user has no existing like to remove (on DELETE).

Validate that the promo code exists before processing the request; return HTTP 404 if not found.
diff --git a/promo_code/business/migrations/0003_promo_like_count.py b/promo_code/business/migrations/0003_promo_like_count.py
@@ -0,0 +1,18 @@
+# Generated by Django 5.2 on 2025-05-13 19:41
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("business", "0002_promo_used_count_alter_company_token_version_and_more"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="promo",
+            name="like_count",
+            field=models.PositiveIntegerField(default=0, editable=False),
+        ),
+    ]
diff --git a/promo_code/business/models.py b/promo_code/business/models.py
@@ -64,6 +64,10 @@ class Promo(django.db.models.Model):
         default=0,
         editable=False,
     )
+    like_count = django.db.models.PositiveIntegerField(
+        default=0,
+        editable=False,
+    )
     active_from = django.db.models.DateField(null=True, blank=True)
     active_until = django.db.models.DateField(null=True, blank=True)
     mode = django.db.models.CharField(
@@ -99,6 +103,10 @@ def is_active(self) -> bool:
 
         return True
 
+    @property
+    def get_like_count(self) -> int:
+        return self.like_count
+
     @property
     def get_used_codes_count(self) -> int:
         if self.mode == business.constants.PROMO_MODE_UNIQUE:
diff --git a/promo_code/business/serializers.py b/promo_code/business/serializers.py
@@ -406,7 +406,10 @@ class PromoReadOnlySerializer(rest_framework.serializers.ModelSerializer):
     target = TargetSerializer()
 
     promo_unique = rest_framework.serializers.SerializerMethodField()
-    like_count = rest_framework.serializers.SerializerMethodField()
+    like_count = rest_framework.serializers.IntegerField(
+        source='get_like_count',
+        read_only=True,
+    )
     used_count = rest_framework.serializers.IntegerField(
         source='get_used_codes_count',
         read_only=True,
@@ -439,10 +442,6 @@ class Meta:
     def get_promo_unique(self, obj):
         return obj.get_available_unique_codes
 
-    def get_like_count(self, obj):
-        # TODO
-        return 0
-
     def to_representation(self, instance):
         data = super().to_representation(instance)
         if instance.mode == business.constants.PROMO_MODE_COMMON:
@@ -476,7 +475,10 @@ class PromoDetailSerializer(rest_framework.serializers.ModelSerializer):
         source='company.name',
         read_only=True,
     )
-    like_count = rest_framework.serializers.SerializerMethodField()
+    like_count = rest_framework.serializers.IntegerField(
+        source='get_like_count',
+        read_only=True,
+    )
     used_count = rest_framework.serializers.IntegerField(
         source='get_used_codes_count',
         read_only=True,
@@ -526,7 +528,3 @@ def validate(self, data):
             instance=self.instance,
         )
         return validator.validate()
-
-    def get_like_count(self, obj):
-        # TODO
-        return 0
diff --git a/promo_code/user/migrations/0002_promolike.py b/promo_code/user/migrations/0002_promolike.py
@@ -0,0 +1,56 @@
+# Generated by Django 5.2 on 2025-05-12 17:44
+
+import django.db.models.deletion
+import uuid
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("business", "0002_promo_used_count_alter_company_token_version_and_more"),
+        ("user", "0001_initial"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="PromoLike",
+            fields=[
+                (
+                    "id",
+                    models.UUIDField(
+                        default=uuid.uuid4,
+                        editable=False,
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="UUID",
+                    ),
+                ),
+                ("created_at", models.DateTimeField(auto_now_add=True)),
+                (
+                    "promo",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="likes",
+                        to="business.promo",
+                    ),
+                ),
+                (
+                    "user",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="promo_likes",
+                        to=settings.AUTH_USER_MODEL,
+                    ),
+                ),
+            ],
+            options={
+                "constraints": [
+                    models.UniqueConstraint(
+                        fields=("user", "promo"), name="unique_like"
+                    )
+                ],
+            },
+        ),
+    ]
diff --git a/promo_code/user/models.py b/promo_code/user/models.py
@@ -4,6 +4,7 @@
 import django.db.models
 import django.utils.timezone
 
+import business.models
 import user.constants
 
 
@@ -82,3 +83,34 @@ def save(self, *args, **kwargs):
             self.last_login = django.utils.timezone.now()
 
         super().save(*args, **kwargs)
+
+
+class PromoLike(django.db.models.Model):
+    id = django.db.models.UUIDField(
+        'UUID',
+        primary_key=True,
+        default=uuid.uuid4,
+        editable=False,
+    )
+    user = django.db.models.ForeignKey(
+        User,
+        on_delete=django.db.models.CASCADE,
+        related_name='promo_likes',
+    )
+    promo = django.db.models.ForeignKey(
+        business.models.Promo,
+        on_delete=django.db.models.CASCADE,
+        related_name='likes',
+    )
+    created_at = django.db.models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        constraints = [
+            django.db.models.UniqueConstraint(
+                fields=['user', 'promo'],
+                name='unique_like',
+            ),
+        ]
+
+    def __str__(self):
+        return f'{self.user} likes {self.promo}'
diff --git a/promo_code/user/serializers.py b/promo_code/user/serializers.py
@@ -342,7 +342,10 @@ class PromoFeedSerializer(rest_framework.serializers.ModelSerializer):
     active = rest_framework.serializers.BooleanField(source='is_active')
     is_activated_by_user = rest_framework.serializers.SerializerMethodField()
     is_liked_by_user = rest_framework.serializers.SerializerMethodField()
-    like_count = rest_framework.serializers.SerializerMethodField()
+    like_count = rest_framework.serializers.IntegerField(
+        source='get_like_count',
+        read_only=True,
+    )
     comment_count = rest_framework.serializers.SerializerMethodField()
 
     class Meta:
@@ -366,10 +369,6 @@ def get_is_activated_by_user(self, obj) -> bool:
         # TODO:
         return False
 
-    def get_like_count(self, obj) -> int:
-        # TODO:
-        return 0
-
     def get_is_liked_by_user(self, obj) -> bool:
         # TODO:
         return False
@@ -403,7 +402,10 @@ class UserPromoDetailSerializer(rest_framework.serializers.ModelSerializer):
         read_only=True,
     )
     is_activated_by_user = rest_framework.serializers.SerializerMethodField()
-    like_count = rest_framework.serializers.SerializerMethodField()
+    like_count = rest_framework.serializers.IntegerField(
+        source='get_like_count',
+        read_only=True,
+    )
     is_liked_by_user = rest_framework.serializers.SerializerMethodField()
     comment_count = rest_framework.serializers.SerializerMethodField()
 
@@ -423,15 +425,20 @@ class Meta:
         )
         read_only_fields = fields
 
-    def get_is_activated_by_user(self, obj) -> bool:
-        # TODO:
+    def get_is_liked_by_user(self, obj: business.models.Promo) -> bool:
+        request = self.context.get('request')
+        if (
+            request
+            and hasattr(request, 'user')
+            and request.user.is_authenticated
+        ):
+            return user.models.PromoLike.objects.filter(
+                promo=obj,
+                user=request.user,
+            ).exists()
         return False
 
-    def get_like_count(self, obj) -> int:
-        # TODO:
-        return 0
-
-    def get_is_liked_by_user(self, obj) -> bool:
+    def get_is_activated_by_user(self, obj) -> bool:
         # TODO:
         return False
 
diff --git a/promo_code/user/urls.py b/promo_code/user/urls.py
@@ -37,4 +37,9 @@
         user.views.UserPromoDetailView.as_view(),
         name='user-promo-detail',
     ),
+    django.urls.path(
+        'promo/<uuid:id>/like',
+        user.views.UserPromoLikeView.as_view(),
+        name='user-promo-like',
+    ),
 ]
diff --git a/promo_code/user/views.py b/promo_code/user/views.py
@@ -1,14 +1,17 @@
 import django.db.models
+import django.shortcuts
 import django.utils.timezone
 import rest_framework.generics
 import rest_framework.permissions
 import rest_framework.response
 import rest_framework.status
+import rest_framework.views
 import rest_framework_simplejwt.tokens
 import rest_framework_simplejwt.views
 
 import business.constants
 import business.models
+import user.models
 import user.pagination
 import user.serializers
 
@@ -224,3 +227,52 @@ def list(self, request, *args, **kwargs):
         self.validated_query_params = query_serializer.validated_data
 
         return super().list(request, *args, **kwargs)
+
+
+class UserPromoLikeView(rest_framework.views.APIView):
+    permission_classes = [rest_framework.permissions.IsAuthenticated]
+
+    def get_promo_object(self, promo_id):
+        return django.shortcuts.get_object_or_404(
+            business.models.Promo,
+            id=promo_id,
+        )
+
+    def post(self, request, id):
+        """Add a like to the promo code."""
+        promo = self.get_promo_object(id)
+
+        created = user.models.PromoLike.objects.get_or_create(
+            user=request.user,
+            promo=promo,
+        )
+
+        if created:
+            promo.like_count = django.db.models.F('like_count') + 1
+            promo.save(update_fields=['like_count'])
+
+        return rest_framework.response.Response(
+            {'status': 'ok'},
+            status=rest_framework.status.HTTP_200_OK,
+        )
+
+    def delete(self, request, id):
+        """Remove a like from the promo code."""
+        promo = self.get_promo_object(id)
+
+        # Idempotency: if the like doesn't exist,
+        # do nothing and still return 200 OK.
+        like_instance = user.models.PromoLike.objects.filter(
+            user=request.user,
+            promo=promo,
+        ).first()
+
+        if like_instance:
+            like_instance.delete()
+            promo.like_count = django.db.models.F('like_count') - 1
+            promo.save(update_fields=['like_count'])
+
+        return rest_framework.response.Response(
+            {'status': 'ok'},
+            status=rest_framework.status.HTTP_200_OK,
+        )
