Merge pull request #59 from RandomProgramm3r/develop

refactor(core, business, serializers): centralize base serializers and streamline promo/user logic

This commit consolidates shared serializer components into the `core` app, removes duplication across apps, and optimizes promo-related view and update logic.

Key changes:
- Centralized serializers  
  - Moved `BaseUserSerializer`, `BaseUserPromoSerializer`, `BaseCommentSerializer`, `BaseCompanyPromoSerializer` (formerly `BasePromoSerializer`), `TargetSerializer`, and `CountryField` into `core/serializers.py` for cross‑app reuse.  
  - Updated `SignUpSerializer`, `UserProfileSerializer`, `PromoFeedSerializer`, `UserPromoDetailSerializer`, and related serializers in `user` and `business` to inherit from these core base classes.  

- Simplified view/query logic  
  - `CompanyPromoListCreateView`: Validates query params directly in `get_queryset` and removes unnecessary overrides of `list()`.  
  - `PromoDetailSerializer#update()`: Calls parent update first, then applies `target` changes to ensure atomic writes and avoid extra saves.  

- Improved pagination & naming  
  - Refactored `UserFeedQuerySerializer` to extend the core `BaseLimitOffsetPaginationSerializer`.  
  - Renamed `BasePromoSerializer` to `BaseCompanyPromoSerializer` for clarity.  

- Enhanced maintainability  
  - Extracted cache invalidation in `UserProfileSerializer` to a private `_invalidate_cache()` method.  
  - Defined `PromoManager.with_related_fields` as a tuple for clearer `only()` semantics.

Author: RandomProgramm3r

promo_code/business/managers.py

@@ -22,6 +22,21 @@ def create_company(self, email, name, password=None, **extra_fields):
 
 
 class PromoManager(django.db.models.Manager):
+    with_related_fields = (
+        'id',
+        'company__id',
+        'company__name',
+        'description',
+        'image_url',
+        'target',
+        'max_count',
+        'active_from',
+        'active_until',
+        'mode',
+        'promo_common',
+        'created_at',
+    )
+
     def get_queryset(self):
         return super().get_queryset()
 
@@ -30,19 +45,7 @@ def with_related(self):
             self.select_related('company')
             .prefetch_related('unique_codes')
             .only(
-                'id',
-                'company',
-                'description',
-                'image_url',
-                'target',
-                'max_count',
-                'active_from',
-                'active_until',
-                'mode',
-                'promo_common',
-                'created_at',
-                'company__id',
-                'company__name',
+                *self.with_related_fields,
             )
         )
 

promo_code/business/serializers.py

@@ -2,7 +2,6 @@
 
 import django.contrib.auth.password_validation
 import django.db.transaction
-import pycountry
 import rest_framework.exceptions
 import rest_framework.serializers
 import rest_framework_simplejwt.exceptions
@@ -140,36 +139,14 @@ def get_active_company_from_token(self, token):
         return company
 
 
-class CountryField(rest_framework.serializers.CharField):
-    """
-    Custom field for validating country codes according to ISO 3166-1 alpha-2.
-    """
-
-    def __init__(self, **kwargs):
-        kwargs['allow_blank'] = False
-        kwargs['min_length'] = business.constants.TARGET_COUNTRY_CODE_LENGTH
-        kwargs['max_length'] = business.constants.TARGET_COUNTRY_CODE_LENGTH
-        super().__init__(**kwargs)
-
-    def to_internal_value(self, data):
-        code = super().to_internal_value(data)
-        try:
-            pycountry.countries.lookup(code.upper())
-        except LookupError:
-            raise rest_framework.serializers.ValidationError(
-                'Invalid ISO 3166-1 alpha-2 country code.',
-            )
-        return code
-
-
 class MultiCountryField(rest_framework.serializers.ListField):
     """
     Custom field for handling multiple country codes,
     passed either as a comma-separated list or as multiple parameters.
     """
 
     def __init__(self, **kwargs):
-        kwargs['child'] = CountryField()
+        kwargs['child'] = core.serializers.CountryField()
         kwargs['allow_empty'] = False
         super().__init__(**kwargs)
 
@@ -196,234 +173,16 @@ def to_internal_value(self, data):
         return super().to_internal_value(data)
 
 
-class TargetSerializer(rest_framework.serializers.Serializer):
-    age_from = rest_framework.serializers.IntegerField(
-        min_value=business.constants.TARGET_AGE_MIN,
-        max_value=business.constants.TARGET_AGE_MAX,
-        required=False,
-    )
-    age_until = rest_framework.serializers.IntegerField(
-        min_value=business.constants.TARGET_AGE_MIN,
-        max_value=business.constants.TARGET_AGE_MAX,
-        required=False,
-    )
-    country = CountryField(required=False)
-
-    categories = rest_framework.serializers.ListField(
-        child=rest_framework.serializers.CharField(
-            min_length=business.constants.TARGET_CATEGORY_MIN_LENGTH,
-            max_length=business.constants.TARGET_CATEGORY_MAX_LENGTH,
-            allow_blank=False,
-        ),
-        max_length=business.constants.TARGET_CATEGORY_MAX_ITEMS,
-        required=False,
-        allow_empty=True,
-    )
-
-    def validate(self, data):
-        age_from = data.get('age_from')
-        age_until = data.get('age_until')
-
-        if (
-            age_from is not None
-            and age_until is not None
-            and age_from > age_until
-        ):
-            raise rest_framework.serializers.ValidationError(
-                {'age_until': 'Must be greater than or equal to age_from.'},
-            )
-        return data
-
-
-class BasePromoSerializer(rest_framework.serializers.ModelSerializer):
-    """
-    Base serializer for promo, containing validation and representation logic.
-    """
-
-    image_url = rest_framework.serializers.URLField(
-        required=False,
-        allow_blank=False,
-        max_length=business.constants.PROMO_IMAGE_URL_MAX_LENGTH,
-    )
-    description = rest_framework.serializers.CharField(
-        min_length=business.constants.PROMO_DESC_MIN_LENGTH,
-        max_length=business.constants.PROMO_DESC_MAX_LENGTH,
-        required=True,
-    )
-    target = TargetSerializer(required=True, allow_null=True)
-    promo_common = rest_framework.serializers.CharField(
-        min_length=business.constants.PROMO_COMMON_CODE_MIN_LENGTH,
-        max_length=business.constants.PROMO_COMMON_CODE_MAX_LENGTH,
-        required=False,
-        allow_null=True,
-        allow_blank=False,
-    )
-    promo_unique = rest_framework.serializers.ListField(
-        child=rest_framework.serializers.CharField(
-            min_length=business.constants.PROMO_UNIQUE_CODE_MIN_LENGTH,
-            max_length=business.constants.PROMO_UNIQUE_CODE_MAX_LENGTH,
-            allow_blank=False,
-        ),
-        min_length=business.constants.PROMO_UNIQUE_LIST_MIN_ITEMS,
-        max_length=business.constants.PROMO_UNIQUE_LIST_MAX_ITEMS,
-        required=False,
-        allow_null=True,
-    )
-
-    class Meta:
-        model = business.models.Promo
-        fields = (
-            'description',
-            'image_url',
-            'target',
-            'max_count',
-            'active_from',
-            'active_until',
-            'mode',
-            'promo_common',
-            'promo_unique',
-        )
-
-    def validate(self, data):
-        """
-        Main validation method.
-        Determines the mode and calls the corresponding validation method.
-        """
-
-        mode = data.get('mode', getattr(self.instance, 'mode', None))
-
-        if mode == business.constants.PROMO_MODE_COMMON:
-            self._validate_common(data)
-        elif mode == business.constants.PROMO_MODE_UNIQUE:
-            self._validate_unique(data)
-        elif mode is None:
-            raise rest_framework.serializers.ValidationError(
-                {'mode': 'This field is required.'},
-            )
-        else:
-            raise rest_framework.serializers.ValidationError(
-                {'mode': 'Invalid mode.'},
-            )
-
-        return data
-
-    def _validate_common(self, data):
-        """
-        Validations for COMMON promo mode.
-        """
-
-        if 'promo_unique' in data and data['promo_unique'] is not None:
-            raise rest_framework.serializers.ValidationError(
-                {'promo_unique': 'This field is not allowed for COMMON mode.'},
-            )
-
-        if self.instance is None and not data.get('promo_common'):
-            raise rest_framework.serializers.ValidationError(
-                {'promo_common': 'This field is required for COMMON mode.'},
-            )
-
-        new_max_count = data.get('max_count')
-        if self.instance and new_max_count is not None:
-            used_count = self.instance.get_used_codes_count
-            if used_count > new_max_count:
-                raise rest_framework.serializers.ValidationError(
-                    {
-                        'max_count': (
-                            f'max_count ({new_max_count}) cannot be less than '
-                            f'used_count ({used_count}).'
-                        ),
-                    },
-                )
-
-        effective_max_count = (
-            new_max_count
-            if new_max_count is not None
-            else getattr(self.instance, 'max_count', None)
-        )
-
-        min_c = business.constants.PROMO_COMMON_MIN_COUNT
-        max_c = business.constants.PROMO_COMMON_MAX_COUNT
-        if effective_max_count is not None and not (
-            min_c <= effective_max_count <= max_c
-        ):
-            raise rest_framework.serializers.ValidationError(
-                {
-                    'max_count': (
-                        f'Must be between {min_c} and {max_c} for COMMON mode.'
-                    ),
-                },
-            )
-
-    def _validate_unique(self, data):
-        """
-        Validations for UNIQUE promo mode.
-        """
-
-        if 'promo_common' in data and data['promo_common'] is not None:
-            raise rest_framework.serializers.ValidationError(
-                {'promo_common': 'This field is not allowed for UNIQUE mode.'},
-            )
-
-        if self.instance is None and not data.get('promo_unique'):
-            raise rest_framework.serializers.ValidationError(
-                {'promo_unique': 'This field is required for UNIQUE mode.'},
-            )
-
-        effective_max_count = data.get(
-            'max_count',
-            getattr(self.instance, 'max_count', None),
-        )
-
-        if (
-            effective_max_count is not None
-            and effective_max_count
-            != business.constants.PROMO_UNIQUE_MAX_COUNT
-        ):
-            raise rest_framework.serializers.ValidationError(
-                {
-                    'max_count': (
-                        'Must be equal to '
-                        f'{business.constants.PROMO_UNIQUE_MAX_COUNT} '
-                        'for UNIQUE mode.'
-                    ),
-                },
-            )
-
-    def to_representation(self, instance):
-        """
-        Controls the display of fields in the response.
-        """
-
-        data = super().to_representation(instance)
-
-        if not instance.image_url:
-            data.pop('image_url', None)
-
-        if instance.mode == business.constants.PROMO_MODE_UNIQUE:
-            data.pop('promo_common', None)
-            if 'promo_unique' in self.fields and isinstance(
-                self.fields['promo_unique'],
-                rest_framework.serializers.SerializerMethodField,
-            ):
-                data['promo_unique'] = self.get_promo_unique(instance)
-            else:
-                data['promo_unique'] = [
-                    code.code for code in instance.unique_codes.all()
-                ]
-        else:
-            data.pop('promo_unique', None)
-
-        return data
-
-
-class PromoCreateSerializer(BasePromoSerializer):
+class PromoCreateSerializer(core.serializers.BaseCompanyPromoSerializer):
     url = rest_framework.serializers.HyperlinkedIdentityField(
         view_name='api-business:promo-detail',
         lookup_field='id',
     )
 
-    class Meta(BasePromoSerializer.Meta):
-        fields = ('url',) + BasePromoSerializer.Meta.fields
+    class Meta(core.serializers.BaseCompanyPromoSerializer.Meta):
+        fields = (
+            'url',
+        ) + core.serializers.BaseCompanyPromoSerializer.Meta.fields
 
     def create(self, validated_data):
         target_data = validated_data.pop('target')
@@ -468,7 +227,7 @@ def validate(self, attrs):
         return attrs
 
 
-class PromoDetailSerializer(BasePromoSerializer):
+class PromoDetailSerializer(core.serializers.BaseCompanyPromoSerializer):
     promo_id = rest_framework.serializers.UUIDField(
         source='id',
         read_only=True,
@@ -496,8 +255,8 @@ class PromoDetailSerializer(BasePromoSerializer):
 
     promo_unique = rest_framework.serializers.SerializerMethodField()
 
-    class Meta(BasePromoSerializer.Meta):
-        fields = BasePromoSerializer.Meta.fields + (
+    class Meta(core.serializers.BaseCompanyPromoSerializer.Meta):
+        fields = core.serializers.BaseCompanyPromoSerializer.Meta.fields + (
             'promo_id',
             'company_name',
             'like_count',
@@ -514,13 +273,12 @@ def get_promo_unique(self, obj):
     def update(self, instance, validated_data):
         target_data = validated_data.pop('target', None)
 
-        for attr, value in validated_data.items():
-            setattr(instance, attr, value)
+        instance = super().update(instance, validated_data)
 
         if target_data is not None:
             instance.target = target_data
+            instance.save(update_fields=['target'])
 
-        instance.save()
         return instance
 
 

promo_code/business/views.py

@@ -74,28 +74,21 @@ class CompanyPromoListCreateView(rest_framework.generics.ListCreateAPIView):
         rest_framework.permissions.IsAuthenticated,
         business.permissions.IsCompanyUser,
     ]
-    # Pagination is only needed for GET (listing)
     pagination_class = core.pagination.CustomLimitOffsetPagination
 
-    _validated_query_params = {}
-
     def get_serializer_class(self):
         if self.request.method == 'POST':
             return business.serializers.PromoCreateSerializer
 
         return business.serializers.PromoReadOnlySerializer
 
-    def list(self, request, *args, **kwargs):
+    def get_queryset(self):
         query_serializer = business.serializers.PromoListQuerySerializer(
-            data=request.query_params,
+            data=self.request.query_params,
         )
         query_serializer.is_valid(raise_exception=True)
-        self._validated_query_params = query_serializer.validated_data
+        params = query_serializer.validated_data
 
-        return super().list(request, *args, **kwargs)
-
-    def get_queryset(self):
-        params = self._validated_query_params
         countries = [c.upper() for c in params.get('countries', [])]
         sort_by = params.get('sort_by')