Add club diff feature

backend/clubs/serializers.py

@@ -878,6 +878,34 @@ class Meta(ClubMinimalSerializer.Meta):
         fields = ClubMinimalSerializer.Meta.fields + ["files"]
 
 
+class ClubDiffSerializer(serializers.ModelSerializer):
+    diff = serializers.SerializerMethodField()
+
+    class Meta:
+        model = Club
+        fields = ["code"]
+
+    def to_representation(self, instance):
+        fields = ["name", "description", "image"]
+        diff = {}
+        is_same = True
+        for field in fields:
+            diff[field] = {
+                "old": getattr(instance, f"latest_approved_{field}", None),
+                "new": getattr(instance, f"latest_{field}", None),
+            }
+            if diff[field]["old"] != diff[field]["new"]:
+                is_same = False
+
+        if is_same:
+            return {
+                instance.code: "No changes that require approval made"
+                + " since last approval"
+            }
+
+        return {instance.code: diff}
+
+
 class ClubListSerializer(serializers.ModelSerializer):
     """
     The club list serializer returns a subset of the information that the full

backend/clubs/views.py

@@ -47,8 +47,10 @@
     ExpressionWrapper,
     F,
     Max,
+    OuterRef,
     Prefetch,
     Q,
+    Subquery,
     TextField,
     Value,
     When,
@@ -163,6 +165,7 @@
     ClubApprovalResponseTemplateSerializer,
     ClubBoothSerializer,
     ClubConstitutionSerializer,
+    ClubDiffSerializer,
     ClubFairSerializer,
     ClubListSerializer,
     ClubMembershipSerializer,
@@ -2127,6 +2130,168 @@ def perform_destroy(self, instance):
             reply_to=settings.OSA_EMAILS + [settings.BRANDING_SITE_EMAIL],
         )
 
+    def _get_club_diff_queryset(self):
+        """
+        Returns a queryset of clubs annotated with the latest and latest approved values
+        for specific fields (name, description, image) from their historical records.
+
+        The annotations include:
+        - `latest_<field>`: The most recent value of the field.
+        - `latest_approved_<field>`: The most recent approved value of the field.
+        """
+        latest_version_qs = Club.history.filter(code=OuterRef("code")).order_by(
+            "-history_date"
+        )
+
+        latest_approved_version_qs = Club.history.filter(
+            code=OuterRef("code"), approved=True
+        ).order_by("-history_date")
+
+        return Club.objects.annotate(
+            latest_name=Subquery(latest_version_qs.values("name")[:1]),
+            latest_description=Subquery(latest_version_qs.values("description")[:1]),
+            latest_image=Subquery(latest_version_qs.values("image")[:1]),
+            latest_approved_name=Subquery(
+                latest_approved_version_qs.values("name")[:1]
+            ),
+            latest_approved_description=Subquery(
+                latest_approved_version_qs.values("description")[:1]
+            ),
+            latest_approved_image=Subquery(
+                latest_approved_version_qs.values("image")[:1]
+            ),
+        )
+
+    @action(detail=True, methods=["GET"])
+    def club_detail_diff(self, request, *args, **kwargs):
+        """
+        Return old and new data for a club that is pending approval.
+        ---
+        responses:
+            "200":
+                content:
+                    application/json:
+                        schema:
+                            type: object
+                            properties:
+                                club_code:
+                                    type: object
+                                    description: club code
+                                    properties:
+                                        name:
+                                            type: object
+                                            description: Changes in the name field
+                                            properties:
+                                                old:
+                                                    type: string
+                                                    description: >
+                                                        Old name of the club
+                                                new:
+                                                    type: string
+                                                    description: >
+                                                        New name of the club
+                                        description:
+                                            type: object
+                                            description: >
+                                                Changes in the club description
+                                            properties:
+                                                old:
+                                                    type: string
+                                                    description: >
+                                                        Old description of the club
+                                                new:
+                                                    type: string
+                                                    description: >
+                                                        New description of the club
+                                        image:
+                                            type: object
+                                            description: >
+                                                Changes in the image of the club
+                                            properties:
+                                                old:
+                                                    type: string
+                                                    description: >
+                                                        Old image URL of the club
+                                                new:
+                                                    type: string
+                                                    description: >
+                                                        New image URL of the club
+        ---
+        """
+        club = self.get_object()
+
+        club = self._get_club_diff_queryset().get(pk=club.pk)
+        serializer = ClubDiffSerializer(club)
+        return Response(serializer.data)
+
+    @action(detail=False, methods=["GET"])
+    def club_list_diff(self, request, *args, **kwargs):
+        """
+        Return old and new data for clubs that are pending approval.
+
+        ---
+        responses:
+            "200":
+                content:
+                    application/json:
+                        schema:
+                            type: array
+                            items:
+                                type: object
+                                additionalProperties:
+                                    type: object
+                                    description: Diff of the club fields.
+                                    properties:
+                                        name:
+                                            type: object
+                                            description: Changes in the name field.
+                                            properties:
+                                                old:
+                                                    type: string
+                                                    nullable: true
+                                                    description: Old name of the club.
+                                                new:
+                                                    type: string
+                                                    nullable: true
+                                                    description: New name of the club.
+                                        description:
+                                            type: object
+                                            description: >
+                                                Changes in the description field.
+                                            properties:
+                                                old:
+                                                    type: string
+                                                    nullable: true
+                                                    description: >
+                                                        Old description of the club.
+                                                new:
+                                                    type: string
+                                                    nullable: true
+                                                    description: >
+                                                        New description of the club.
+                                        image:
+                                            type: object
+                                            description: Changes in the image field.
+                                            properties:
+                                                old:
+                                                    type: string
+                                                    nullable: true
+                                                    description: >
+                                                        Old image URL of the club.
+                                                new:
+                                                    type: string
+                                                    nullable: true
+                                                    description: >
+                                                        New image URL of the club.
+        ---
+        """
+
+        pending_clubs = self._get_club_diff_queryset().filter(
+            approved=None, active=True
+        )
+        serializer = ClubDiffSerializer(pending_clubs, many=True)
+        return Response(serializer.data)
+
     @action(detail=False, methods=["GET"])
     def fields(self, request, *args, **kwargs):
         """