✨(backend) add Comment model

In order to store the comments on a document, we created a new model
Comment. User is nullable because anonymous users can comment a Document
is this one is public with a link_role commentator.

Author: lunika

src/backend/core/factories.py

@@ -256,3 +256,14 @@ class Meta:
     document = factory.SubFactory(DocumentFactory)
     role = factory.fuzzy.FuzzyChoice([role[0] for role in models.RoleChoices.choices])
     issuer = factory.SubFactory(UserFactory)
+
+
+class CommentFactory(factory.django.DjangoModelFactory):
+    """A factory to create comments for a document"""
+
+    class Meta:
+        model = models.Comment
+
+    document = factory.SubFactory(DocumentFactory)
+    user = factory.SubFactory(UserFactory)
+    content = factory.Faker("text")

src/backend/core/migrations/0025_alter_document_link_role_alter_documentaccess_role_and_more.py

@@ -0,0 +1,146 @@
+# Generated by Django 5.2.4 on 2025-08-26 08:11
+
+import uuid
+
+import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("core", "0024_add_is_masked_field_to_link_trace"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="document",
+            name="link_role",
+            field=models.CharField(
+                choices=[
+                    ("reader", "Reader"),
+                    ("commentator", "Commentator"),
+                    ("editor", "Editor"),
+                ],
+                default="reader",
+                max_length=20,
+            ),
+        ),
+        migrations.AlterField(
+            model_name="documentaccess",
+            name="role",
+            field=models.CharField(
+                choices=[
+                    ("reader", "Reader"),
+                    ("commentator", "Commentator"),
+                    ("editor", "Editor"),
+                    ("administrator", "Administrator"),
+                    ("owner", "Owner"),
+                ],
+                default="reader",
+                max_length=20,
+            ),
+        ),
+        migrations.AlterField(
+            model_name="documentaskforaccess",
+            name="role",
+            field=models.CharField(
+                choices=[
+                    ("reader", "Reader"),
+                    ("commentator", "Commentator"),
+                    ("editor", "Editor"),
+                    ("administrator", "Administrator"),
+                    ("owner", "Owner"),
+                ],
+                default="reader",
+                max_length=20,
+            ),
+        ),
+        migrations.AlterField(
+            model_name="invitation",
+            name="role",
+            field=models.CharField(
+                choices=[
+                    ("reader", "Reader"),
+                    ("commentator", "Commentator"),
+                    ("editor", "Editor"),
+                    ("administrator", "Administrator"),
+                    ("owner", "Owner"),
+                ],
+                default="reader",
+                max_length=20,
+            ),
+        ),
+        migrations.AlterField(
+            model_name="templateaccess",
+            name="role",
+            field=models.CharField(
+                choices=[
+                    ("reader", "Reader"),
+                    ("commentator", "Commentator"),
+                    ("editor", "Editor"),
+                    ("administrator", "Administrator"),
+                    ("owner", "Owner"),
+                ],
+                default="reader",
+                max_length=20,
+            ),
+        ),
+        migrations.CreateModel(
+            name="Comment",
+            fields=[
+                (
+                    "id",
+                    models.UUIDField(
+                        default=uuid.uuid4,
+                        editable=False,
+                        help_text="primary key for the record as UUID",
+                        primary_key=True,
+                        serialize=False,
+                        verbose_name="id",
+                    ),
+                ),
+                (
+                    "created_at",
+                    models.DateTimeField(
+                        auto_now_add=True,
+                        help_text="date and time at which a record was created",
+                        verbose_name="created on",
+                    ),
+                ),
+                (
+                    "updated_at",
+                    models.DateTimeField(
+                        auto_now=True,
+                        help_text="date and time at which a record was last updated",
+                        verbose_name="updated on",
+                    ),
+                ),
+                ("content", models.TextField()),
+                (
+                    "document",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.CASCADE,
+                        related_name="comments",
+                        to="core.document",
+                    ),
+                ),
+                (
+                    "user",
+                    models.ForeignKey(
+                        blank=True,
+                        null=True,
+                        on_delete=django.db.models.deletion.SET_NULL,
+                        related_name="comments",
+                        to=settings.AUTH_USER_MODEL,
+                    ),
+                ),
+            ],
+            options={
+                "verbose_name": "Comment",
+                "verbose_name_plural": "Comments",
+                "db_table": "impress_comment",
+                "ordering": ("-created_at",),
+            },
+        ),
+    ]

src/backend/core/models.py

@@ -1282,6 +1282,48 @@ def send_ask_for_access_email(self, email, language=None):
         self.document.send_email(subject, [email], context, language)
 
 
+class Comment(BaseModel):
+    """User comment on a document."""
+
+    document = models.ForeignKey(
+        Document,
+        on_delete=models.CASCADE,
+        related_name="comments",
+    )
+    user = models.ForeignKey(
+        User,
+        on_delete=models.SET_NULL,
+        related_name="comments",
+        null=True,
+        blank=True,
+    )
+    content = models.TextField()
+
+    class Meta:
+        db_table = "impress_comment"
+        ordering = ("-created_at",)
+        verbose_name = _("Comment")
+        verbose_name_plural = _("Comments")
+
+    def __str__(self):
+        author = self.user or _("Anonymous")
+        return f"{author!s} on {self.document!s}"
+
+    def get_abilities(self, user):
+        """Compute and return abilities for a given user."""
+        role = self.document.get_role(user)
+        can_comment = self.document.get_abilities(user)["comment"]
+        return {
+            "destroy": self.user == user
+            or role in [RoleChoices.OWNER, RoleChoices.ADMIN],
+            "update": self.user == user
+            or role in [RoleChoices.OWNER, RoleChoices.ADMIN],
+            "partial_update": self.user == user
+            or role in [RoleChoices.OWNER, RoleChoices.ADMIN],
+            "retrieve": can_comment,
+        }
+
+
 class Template(BaseModel):
     """HTML and CSS code used for formatting the print around the MarkDown body."""