✨(backend) add creator field on document and allow filtering on it

We want to be able to limit the documents displayed on a logged-in user's
list view by the documents they created or by the documents that other
users created.

This is different from having the "owner" role on a document because this
can be acquired and even lost. What we want here is to be able to
identify documents by the user who created them so we add a new field.

src/backend/core/api/filters.py

@@ -0,0 +1,63 @@
+"""API filters for Impress' core application."""
+
+from django.utils.translation import gettext_lazy as _
+
+import django_filters
+
+from core import models
+
+
+class DocumentFilter(django_filters.FilterSet):
+    """
+    Custom filter for filtering documents.
+    """
+
+    is_creator_me = django_filters.BooleanFilter(
+        method="filter_is_creator_me", label=_("Creator is me")
+    )
+
+    class Meta:
+        model = models.Document
+        fields = ["is_creator_me"]
+
+    # pylint: disable=unused-argument
+    def filter_is_creator_me(self, queryset, name, value):
+        """
+        Filter documents based on the `creator` being the current user.
+
+        Example:
+            - /api/v1.0/documents/?is_creator_me=true
+                → Filters documents created by the logged-in user
+            - /api/v1.0/documents/?is_creator_me=false
+                → Filters documents created by other users
+        """
+        user = self.request.user
+
+        if not user.is_authenticated:
+            return queryset
+
+        if value:
+            return queryset.filter(creator=user)
+
+        return queryset.exclude(creator=user)
+
+    # pylint: disable=unused-argument
+    def filter_is_favorite(self, queryset, name, value):
+        """
+        Filter documents based on whether they are marked as favorite by the current user.
+
+        Example:
+            - /api/v1.0/documents/?favorite=true
+                → Filters documents marked as favorite by the logged-in user
+            - /api/v1.0/documents/?favorite=false
+                → Filters documents not marked as favorite by the logged-in user
+        """
+        user = self.request.user
+
+        if not user.is_authenticated:
+            return queryset
+
+        clause = "filter" if value else "exclude"
+        return getattr(queryset, clause)(
+            favorited_by_users__user=user, favorited_by_users__is_favorite=True
+        )

src/backend/core/api/serializers.py

@@ -150,6 +150,7 @@ class ListDocumentSerializer(BaseResourceSerializer):
             "abilities",
             "content",
             "created_at",
+            "creator",
             "is_favorite",
             "link_role",
             "link_reach",
@@ -161,6 +162,7 @@ class ListDocumentSerializer(BaseResourceSerializer):
             "id",
             "abilities",
             "created_at",
+            "creator",
             "is_favorite",
             "link_role",
             "link_reach",
@@ -181,6 +183,7 @@ class DocumentSerializer(ListDocumentSerializer):
             "abilities",
             "content",
             "created_at",
+            "creator",
             "is_favorite",
             "link_role",
             "link_reach",
@@ -192,6 +195,7 @@ class DocumentSerializer(ListDocumentSerializer):
             "id",
             "abilities",
             "created_at",
+            "creator",
             "is_avorite",
             "link_role",
             "link_reach",

src/backend/core/api/viewsets.py

@@ -22,10 +22,10 @@ from django.db.models import (
 from django.http import Http404
 
 from botocore.exceptions import ClientError
+from django_filters import rest_framework as filters
 from rest_framework import (
     decorators,
     exceptions,
-    filters,
     metadata,
     mixins,
     pagination,
@@ -33,6 +33,9 @@ from rest_framework import (
     views,
     viewsets,
 )
+from rest_framework import (
+    filters as drf_filters,
+)
 from rest_framework import (
     response as drf_response,
 )
@@ -42,6 +45,7 @@ from core import enums, models
 from core.services.ai_services import AIService
 
 from . import permissions, serializers, utils
+from .filters import DocumentFilter
 
 ATTACHMENTS_FOLDER = "attachments"
 UUID_REGEX = (
@@ -311,9 +315,23 @@ class DocumentViewSet(
     mixins.UpdateModelMixin,
     viewsets.GenericViewSet,
 ):
-    """Document ViewSet"""
+    """
+    Document ViewSet for managing documents.
 
-    filter_backends = [filters.OrderingFilter]
+    Provides endpoints for creating, updating, and deleting documents,
+    along with filtering options.
+
+    Filtering:
+        - `is_creator_me=true`: Returns documents created by the current user.
+        - `is_creator_me=false`: Returns documents created by other users.
+
+    Example Usage:
+        - GET /api/v1.0/documents/?creator=me
+        - GET /api/v1.0/documents/?creator=other
+    """
+
+    filter_backends = [filters.DjangoFilterBackend, drf_filters.OrderingFilter]
+    filterset_class = DocumentFilter
     metadata_class = DocumentMetadata
     ordering = ["-updated_at"]
     ordering_fields = ["created_at", "is_favorite", "updated_at", "title"]
@@ -410,8 +428,8 @@ class DocumentViewSet(
         return drf_response.Response(serializer.data)
 
     def perform_create(self, serializer):
-        """Set the current user as owner of the newly created object."""
-        obj = serializer.save()
+        """Set the current user as creator and owner of the newly created object."""
+        obj = serializer.save(creator=self.request.user)
         models.DocumentAccess.objects.create(
             document=obj,
             user=self.request.user,
@@ -739,7 +757,7 @@ class TemplateViewSet(
 ):
     """Template ViewSet"""
 
-    filter_backends = [filters.OrderingFilter]
+    filter_backends = [drf_filters.OrderingFilter]
     permission_classes = [
         permissions.IsAuthenticatedOrSafe,
         permissions.AccessPermission,