Object: remove context_id field

30 to 70% of the objects in the object table are simple JSON objects
containing a single field, 'id', being the context's ID. The reason for
the creation of an object per context seems to be an old relic from the
StatusNet era, and has only been used nowadays as an helper for threads
in Pleroma-FE via the `pleroma.conversation_id` field in status views.
An object per context was created, and its numerical ID (table column)
was used and stored as 'context_id' in the object and activity along
with the full 'context' URI/string.

This commit removes this field and stops creation of objects for each
context, which will also allow incoming activities to use activity IDs
as contexts, something which was not possible before, or would have been
very broken under most circumstances.

The `pleroma.conversation_id` field has been reimplemented in a way to
maintain backwards-compatibility by calculating a CRC32 of the full
context URI/string in the object, instead of relying on the row ID for
the created context object.

lib/pleroma/object.ex

@@ -208,10 +208,6 @@ def get_cached_by_ap_id(ap_id) do
     end
   end
 
-  def context_mapping(context) do
-    Object.change(%Object{}, %{data: %{"id" => context}})
-  end
-
   def make_tombstone(%Object{data: %{"id" => id, "type" => type}}, deleted \\ DateTime.utc_now()) do
     %ObjectTombstone{
       id: id,

lib/pleroma/web/activity_pub/object_validators/article_note_page_validator.ex

@@ -174,7 +174,7 @@ def changeset(struct, data) do
   defp validate_data(data_cng) do
     data_cng
     |> validate_inclusion(:type, ["Article", "Note", "Page"])
-    |> validate_required([:id, :actor, :attributedTo, :type, :context, :context_id])
+    |> validate_required([:id, :actor, :attributedTo, :type, :context])
     |> CommonValidations.validate_any_presence([:cc, :to])
     |> CommonValidations.validate_fields_match([:actor, :attributedTo])
     |> CommonValidations.validate_actor_presence()

lib/pleroma/web/activity_pub/object_validators/common_fixes.ex

@@ -22,14 +22,12 @@ def cast_and_filter_recipients(message, field, follower_collection, field_fallba
   end
 
   def fix_object_defaults(data) do
-    %{data: %{"id" => context}, id: context_id} =
+    context = Utils.maybe_create_context(data["context"] || data["conversation"])
-      Utils.create_context(data["context"] || data["conversation"])
 
     %User{follower_address: follower_collection} = User.get_cached_by_ap_id(data["attributedTo"])
 
     data
     |> Map.put("context", context)
-    |> Map.put("context_id", context_id)
     |> cast_and_filter_recipients("to", follower_collection)
     |> cast_and_filter_recipients("cc", follower_collection)
     |> cast_and_filter_recipients("bto", follower_collection)

lib/pleroma/web/activity_pub/object_validators/event_validator.ex

@@ -62,7 +62,7 @@ def changeset(struct, data) do
   defp validate_data(data_cng) do
     data_cng
     |> validate_inclusion(:type, ["Event"])
-    |> validate_required([:id, :actor, :attributedTo, :type, :context, :context_id])
+    |> validate_required([:id, :actor, :attributedTo, :type, :context])
     |> CommonValidations.validate_any_presence([:cc, :to])
     |> CommonValidations.validate_fields_match([:actor, :attributedTo])
     |> CommonValidations.validate_actor_presence()

lib/pleroma/web/activity_pub/object_validators/question_validator.ex

@@ -80,7 +80,7 @@ def changeset(struct, data) do
   defp validate_data(data_cng) do
     data_cng
     |> validate_inclusion(:type, ["Question"])
-    |> validate_required([:id, :actor, :attributedTo, :type, :context, :context_id])
+    |> validate_required([:id, :actor, :attributedTo, :type, :context])
     |> CommonValidations.validate_any_presence([:cc, :to])
     |> CommonValidations.validate_fields_match([:actor, :attributedTo])
     |> CommonValidations.validate_actor_presence()

lib/pleroma/web/activity_pub/utils.ex

@@ -154,22 +154,7 @@ def get_notified_from_object(object) do
     Notification.get_notified_from_activity(%Activity{data: object}, false)
   end
 
-  def create_context(context) do
+  def maybe_create_context(context), do: context || generate_id("contexts")
-    context = context || generate_id("contexts")
-
-    # Ecto has problems accessing the constraint inside the jsonb,
-    # so we explicitly check for the existed object before insert
-    object = Object.get_cached_by_ap_id(context)
-
-    with true <- is_nil(object),
-         changeset <- Object.context_mapping(context),
-         {:ok, inserted_object} <- Repo.insert(changeset) do
-      inserted_object
-    else
-      _ ->
-        object
-    end
-  end
 
   @doc """
   Enqueues an activity for federation if it's local
@@ -201,18 +186,16 @@ def lazy_put_activity_defaults(map, true) do
     |> Map.put_new("id", "pleroma:fakeid")
     |> Map.put_new_lazy("published", &make_date/0)
     |> Map.put_new("context", "pleroma:fakecontext")
-    |> Map.put_new("context_id", -1)
     |> lazy_put_object_defaults(true)
   end
 
   def lazy_put_activity_defaults(map, _fake?) do
-    %{data: %{"id" => context}, id: context_id} = create_context(map["context"])
+    context = maybe_create_context(map["context"])
 
     map
     |> Map.put_new_lazy("id", &generate_activity_id/0)
     |> Map.put_new_lazy("published", &make_date/0)
     |> Map.put_new("context", context)
-    |> Map.put_new("context_id", context_id)
     |> lazy_put_object_defaults(false)
   end
 
@@ -226,7 +209,6 @@ defp lazy_put_object_defaults(%{"object" => map} = activity, true)
       |> Map.put_new("id", "pleroma:fake_object_id")
       |> Map.put_new_lazy("published", &make_date/0)
       |> Map.put_new("context", activity["context"])
-      |> Map.put_new("context_id", activity["context_id"])
       |> Map.put_new("fake", true)
 
     %{activity | "object" => object}
@@ -239,7 +221,6 @@ defp lazy_put_object_defaults(%{"object" => map} = activity, _)
       |> Map.put_new_lazy("id", &generate_object_id/0)
       |> Map.put_new_lazy("published", &make_date/0)
       |> Map.put_new("context", activity["context"])
-      |> Map.put_new("context_id", activity["context_id"])
 
     %{activity | "object" => object}
   end

lib/pleroma/web/common_api/utils.ex

@@ -458,35 +458,6 @@ def get_report_statuses(%User{ap_id: actor}, %{status_ids: status_ids})
 
   def get_report_statuses(_, _), do: {:ok, nil}
 
-  # DEPRECATED mostly, context objects are now created at insertion time.
-  def context_to_conversation_id(context) do
-    with %Object{id: id} <- Object.get_cached_by_ap_id(context) do
-      id
-    else
-      _e ->
-        changeset = Object.context_mapping(context)
-
-        case Repo.insert(changeset) do
-          {:ok, %{id: id}} ->
-            id
-
-          # This should be solved by an upsert, but it seems ecto
-          # has problems accessing the constraint inside the jsonb.
-          {:error, _} ->
-            Object.get_cached_by_ap_id(context).id
-        end
-    end
-  end
-
-  def conversation_id_to_context(id) do
-    with %Object{data: %{"id" => context}} <- Repo.get(Object, id) do
-      context
-    else
-      _e ->
-        {:error, dgettext("errors", "No such conversation")}
-    end
-  end
-
   def validate_character_limit("" = _full_payload, [] = _attachments) do
     {:error, dgettext("errors", "Cannot post an empty status without attachments")}
   end

lib/pleroma/web/mastodon_api/views/status_view.ex

@@ -61,7 +61,7 @@ defp get_context_id(%{data: %{"context_id" => context_id}}) when not is_nil(cont
     do: context_id
 
   defp get_context_id(%{data: %{"context" => context}}) when is_binary(context),
-    do: Utils.context_to_conversation_id(context)
+    do: :erlang.crc32(context)
 
   defp get_context_id(_), do: nil
 

test/pleroma/web/activity_pub/activity_pub_test.exs

@@ -523,7 +523,6 @@ test "inserts a given map into the activity database, giving it an id if it has
       assert activity.data["ok"] == data["ok"]
       assert activity.data["id"] == given_id
       assert activity.data["context"] == "blabla"
-      assert activity.data["context_id"]
     end
 
     test "adds a context when none is there" do
@@ -545,8 +544,6 @@ test "adds a context when none is there" do
 
       assert is_binary(activity.data["context"])
       assert is_binary(object.data["context"])
-      assert activity.data["context_id"]
-      assert object.data["context_id"]
     end
 
     test "adds an id to a given object if it lacks one and is a note and inserts it to the object database" do
@@ -1560,7 +1557,7 @@ test "it can create a Flag activity",
                })
 
       assert Repo.aggregate(Activity, :count, :id) == 1
-      assert Repo.aggregate(Object, :count, :id) == 2
+      assert Repo.aggregate(Object, :count, :id) == 1
       assert Repo.aggregate(Notification, :count, :id) == 0
     end
   end

test/pleroma/web/activity_pub/transmogrifier/question_handling_test.exs

@@ -33,8 +33,6 @@ test "Mastodon Question activity" do
     assert object.data["context"] ==
              "tag:mastodon.sdf.org,2019-05-10:objectId=15095122:objectType=Conversation"
 
-    assert object.data["context_id"]
-
     assert object.data["anyOf"] == []
 
     assert Enum.sort(object.data["oneOf"]) ==
@@ -68,7 +66,6 @@ test "Mastodon Question activity" do
     reply_object = Object.normalize(reply_activity, fetch: false)
 
     assert reply_object.data["context"] == object.data["context"]
-    assert reply_object.data["context_id"] == object.data["context_id"]
   end
 
   test "Mastodon Question activity with HTML tags in plaintext" do

test/pleroma/web/activity_pub/transmogrifier_test.exs

@@ -232,7 +232,6 @@ test "it strips internal fields" do
       assert is_nil(modified["object"]["like_count"])
       assert is_nil(modified["object"]["announcements"])
       assert is_nil(modified["object"]["announcement_count"])
-      assert is_nil(modified["object"]["context_id"])
       assert is_nil(modified["object"]["generator"])
     end
 
@@ -247,7 +246,6 @@ test "it strips internal fields of article" do
       assert is_nil(modified["object"]["like_count"])
       assert is_nil(modified["object"]["announcements"])
       assert is_nil(modified["object"]["announcement_count"])
-      assert is_nil(modified["object"]["context_id"])
       assert is_nil(modified["object"]["likes"])
     end
 

test/pleroma/web/activity_pub/utils_test.exs

@@ -429,7 +429,6 @@ test "returns map with id and published data" do
       object = Object.normalize(note_activity, fetch: false)
       res = Utils.lazy_put_activity_defaults(%{"context" => object.data["id"]})
       assert res["context"] == object.data["id"]
-      assert res["context_id"] == object.id
       assert res["id"]
       assert res["published"]
     end
@@ -437,7 +436,6 @@ test "returns map with id and published data" do
     test "returns map with fake id and published data" do
       assert %{
                "context" => "pleroma:fakecontext",
-               "context_id" => -1,
                "id" => "pleroma:fakeid",
                "published" => _
              } = Utils.lazy_put_activity_defaults(%{}, true)
@@ -454,13 +452,11 @@ test "returns activity data with object" do
         })
 
       assert res["context"] == object.data["id"]
-      assert res["context_id"] == object.id
       assert res["id"]
       assert res["published"]
       assert res["object"]["id"]
       assert res["object"]["published"]
       assert res["object"]["context"] == object.data["id"]
-      assert res["object"]["context_id"] == object.id
     end
   end
 

test/pleroma/web/common_api/utils_test.exs

@@ -273,22 +273,6 @@ test "delegated renderers" do
     end
   end
 
-  describe "context_to_conversation_id" do
-    test "creates a mapping object" do
-      conversation_id = Utils.context_to_conversation_id("random context")
-      object = Object.get_by_ap_id("random context")
-
-      assert conversation_id == object.id
-    end
-
-    test "returns an existing mapping for an existing object" do
-      {:ok, object} = Object.context_mapping("random context") |> Repo.insert()
-      conversation_id = Utils.context_to_conversation_id("random context")
-
-      assert conversation_id == object.id
-    end
-  end
-
   describe "formats date to asctime" do
     test "when date is in ISO 8601 format" do
       date = DateTime.utc_now() |> DateTime.to_iso8601()
@@ -517,17 +501,6 @@ test "returns empty string when date invalid" do
     end
   end
 
-  describe "conversation_id_to_context/1" do
-    test "returns id" do
-      object = insert(:note)
-      assert Utils.conversation_id_to_context(object.id) == object.data["id"]
-    end
-
-    test "returns error if object not found" do
-      assert Utils.conversation_id_to_context("123") == {:error, "No such conversation"}
-    end
-  end
-
   describe "maybe_notify_mentioned_recipients/2" do
     test "returns recipients when activity is not `Create`" do
       activity = insert(:like_activity)

test/pleroma/web/mastodon_api/views/status_view_test.exs

@@ -240,7 +240,7 @@ test "a note activity" do
     object_data = Object.normalize(note, fetch: false).data
     user = User.get_cached_by_ap_id(note.data["actor"])
 
-    convo_id = Utils.context_to_conversation_id(object_data["context"])
+    convo_id = :erlang.crc32(object_data["context"])
 
     status = StatusView.render("show.json", %{activity: note})