drafts: Send events to clients when drafts change.

With this, the core of the new drafts system is complete.

zerver/lib/drafts.py

@@ -24,6 +24,7 @@ from zerver.lib.validator import (
     check_union,
 )
 from zerver.models import Draft, UserProfile
+from zerver.tornado.django_api import send_event
 
 VALID_DRAFT_TYPES: Set[str] = {"", "private", "stream"}
 
@@ -117,6 +118,14 @@ def do_create_drafts(draft_dicts: List[Dict[str, Any]], user_profile: UserProfil
         )
 
     created_draft_objects = Draft.objects.bulk_create(draft_objects)
+
+    event = {
+        "type": "drafts",
+        "op": "add",
+        "drafts": [draft.to_dict() for draft in created_draft_objects],
+    }
+    send_event(user_profile.realm, event, [user_profile.id])
+
     return created_draft_objects
 
 
@@ -135,6 +144,9 @@ def do_edit_draft(draft_id: int, draft_dict: Dict[str, Any], user_profile: UserP
     draft_object.last_edit_time = valid_draft_dict["last_edit_time"]
     draft_object.save()
 
+    event = {"type": "drafts", "op": "update", "draft": draft_object.to_dict()}
+    send_event(user_profile.realm, event, [user_profile.id])
+
 
 def do_delete_draft(draft_id: int, user_profile: UserProfile) -> None:
     """Delete a draft belonging to a particular user."""
@@ -142,4 +154,9 @@ def do_delete_draft(draft_id: int, user_profile: UserProfile) -> None:
         draft_object = Draft.objects.get(id=draft_id, user_profile=user_profile)
     except Draft.DoesNotExist:
         raise ResourceNotFoundError(_("Draft does not exist"))
+
+    draft_id = draft_object.id
     draft_object.delete()
+
+    event = {"type": "drafts", "op": "remove", "draft_id": draft_id}
+    send_event(user_profile.realm, event, [user_profile.id])

zerver/lib/events.py

@@ -54,6 +54,7 @@ from zerver.models import (
     MAX_TOPIC_NAME_LENGTH,
     Client,
     CustomProfileField,
+    Draft,
     Message,
     Realm,
     Stream,
@@ -169,6 +170,17 @@ def fetch_initial_state_data(
         else:
             state["max_message_id"] = -1
 
+    if want("drafts"):
+        # Note: if a user ever disables synching drafts then all of
+        # their old drafts stored on the server will be deleted and
+        # simply retained in local storage. In which case user_drafts
+        # would just be an empty queryset.
+        user_draft_objects = Draft.objects.filter(user_profile=user_profile).order_by(
+            "-last_edit_time"
+        )[: settings.MAX_DRAFTS_IN_REGISTER_RESPONSE]
+        user_draft_dicts = [draft.to_dict() for draft in user_draft_objects]
+        state["drafts"] = user_draft_dicts
+
     if want("muted_topics"):
         state["muted_topics"] = [] if user_profile is None else get_topic_mutes(user_profile)
 
@@ -618,6 +630,34 @@ def apply_event(
         # It may be impossible for a heartbeat event to actually reach
         # this code path. But in any case, they're noops.
         pass
+
+    elif event["type"] == "drafts":
+        if event["op"] == "add":
+            state["drafts"].extend(event["drafts"])
+        else:
+            if event["op"] == "update":
+                event_draft_idx = event["draft"]["id"]
+
+                def _draft_update_action(i: int) -> None:
+                    state["drafts"][i] = event["draft"]
+
+            elif event["op"] == "remove":
+                event_draft_idx = event["draft_id"]
+
+                def _draft_update_action(i: int) -> None:
+                    del state["drafts"][i]
+
+            # We have to perform a linear search for the draft that
+            # was either edited or removed since we have a list
+            # ordered by the last edited timestamp and not id.
+            state_draft_idx = None
+            for idx, draft in enumerate(state["drafts"]):
+                if draft["id"] == event_draft_idx:
+                    state_draft_idx = idx
+                    break
+            assert state_draft_idx is not None
+            _draft_update_action(state_draft_idx)
+
     elif event["type"] == "hotspots":
         state["hotspots"] = event["hotspots"]
     elif event["type"] == "custom_profile_fields":

zerver/openapi/zulip.yaml

@@ -3818,6 +3818,102 @@ paths:
                                     },
                                   "id": 0,
                                 }
+                            - type: object
+                              additionalProperties: false
+                              description: |
+                                Event containing details of newly created drafts.
+                              properties:
+                                id:
+                                  $ref: "#/components/schemas/EventIdSchema"
+                                type:
+                                  allOf:
+                                    - $ref: "#/components/schemas/EventTypeSchema"
+                                    - enum:
+                                        - "drafts"
+                                op:
+                                  type: string
+                                  enum:
+                                    - "add"
+                                drafts:
+                                  type: array
+                                  description: |
+                                    An array containing objects for the newly created drafts.
+                                  items:
+                                    $ref: "#/components/schemas/Draft"
+                              example:
+                                {
+                                  "type": "drafts",
+                                  "op": "add",
+                                  "drafts":
+                                    [
+                                      {
+                                        "id": 17,
+                                        "type": "private",
+                                        "to": [6],
+                                        "topic": "",
+                                        "content": "Hello there!",
+                                        "timestamp": 15954790200,
+                                      },
+                                    ],
+                                }
+                            - type: object
+                              additionalProperties: false
+                              description: |
+                                Event containing details for an edited draft.
+                              properties:
+                                id:
+                                  $ref: "#/components/schemas/EventIdSchema"
+                                type:
+                                  allOf:
+                                    - $ref: "#/components/schemas/EventTypeSchema"
+                                    - enum:
+                                        - "drafts"
+                                op:
+                                  type: string
+                                  enum:
+                                    - "update"
+                                draft:
+                                  $ref: "#/components/schemas/Draft"
+                              example:
+                                {
+                                  "type": "drafts",
+                                  "op": "update",
+                                  "draft":
+                                    {
+                                      "id": 17,
+                                      "type": "private",
+                                      "to": [6, 7, 8, 9, 10],
+                                      "topic": "",
+                                      "content": "Hello everyone!",
+                                      "timestamp": 15954790200,
+                                    },
+                                }
+                            - type: object
+                              additionalProperties: false
+                              description: |
+                                Event containing the id of a deleted draft.
+                              properties:
+                                id:
+                                  $ref: "#/components/schemas/EventIdSchema"
+                                type:
+                                  allOf:
+                                    - $ref: "#/components/schemas/EventTypeSchema"
+                                    - enum:
+                                        - "drafts"
+                                op:
+                                  type: string
+                                  enum:
+                                    - "remove"
+                                draft_id:
+                                  type: integer
+                                  description: |
+                                    The ID of the draft that was just deleted.
+                              example:
+                                {
+                                  "type": "drafts",
+                                  "op": "update",
+                                  "draft_id": 17,
+                                }
                       queue_id:
                         type: string
                         description: |
@@ -7980,6 +8076,14 @@ paths:
                               type: string
                               description: |
                                 The name of the custom profile field type.
+                      drafts:
+                        type: array
+                        description: |
+                          An array containing draft objects for the user. These drafts are being
+                          stored on the backend for the purpose of syncing across devices. This
+                          array will be empty if `enable_drafts_synchronization` is set to `false`.
+                        items:
+                          $ref: "#/components/schemas/Draft"
                       hotspots:
                         type: array
                         description: |
@@ -8835,7 +8939,8 @@ paths:
                         description: |
                           Present if `update_display_settings` is present in `fetch_event_types`.
 
-                          Whether drafts synchronization is enabled for the user.
+                          Whether drafts synchronization is enabled for the user. If disabled,
+                          clients will receive an error when trying to use the `drafts` endpoints.
 
                           See [PATCH /settings](/api/update-settings) for details on
                           the meaning of this setting.
@@ -12800,6 +12905,59 @@ components:
           description: |
             Whether the client is capable of showing mobile/push notifications
             to the user.
+    Draft:
+      type: object
+      description: |
+        A dictionary for representing a message draft.
+      properties:
+        id:
+          type: integer
+          description: |
+            The unique ID of the draft. It will only used whenever the drafts are
+            fetched. This field should not be specified when the draft is being
+            created or edited.
+        type:
+          type: string
+          description: |
+            The type of the draft. Either unaddressed (empty string), "stream",
+            or "private" (for PMs and private group messages).
+          enum:
+            - ""
+            - "stream"
+            - "private"
+        to:
+          type: array
+          description: |
+            An array of the tentative target audience IDs. For "stream"
+            messages, this should contain exactly 1 ID, the ID of the
+            target stream. For private messages, this should be an array
+            of target user IDs. For unaddressed drafts this is ignored
+            so it's best to leave it as an empty array.
+          items:
+            type: integer
+        topic:
+          type: string
+          description: |
+            For stream message drafts, the tentative topic name. For private
+            or unaddressed messages this will be ignored and should ideally
+            be an empty string. Should not contain null bytes.
+        content:
+          type: string
+          description: |
+            The body of the draft. Should not contain null bytes.
+        timestamp:
+          type: number
+          description: |
+            A Unix timestamp (seconds only) representing when the draft was
+            last edited. When creating a draft, this key need not be present
+            and it will be filled in automatically by the server.
+          example: 1595479019
+      additionalProperties: false
+      required:
+        - type
+        - to
+        - topic
+        - content
     User:
       allOf:
         - $ref: "#/components/schemas/UserBase"

zerver/tests/test_event_system.py

@@ -980,13 +980,14 @@ class FetchQueriesTest(ZulipTestCase):
             with mock.patch("zerver.lib.events.always_want") as want_mock:
                 fetch_initial_state_data(user)
 
-        self.assert_length(queries, 33)
+        self.assert_length(queries, 34)
 
         expected_counts = dict(
             alert_words=1,
             custom_profile_fields=1,
             default_streams=1,
             default_stream_groups=1,
+            drafts=1,
             hotspots=0,
             message=1,
             muted_topics=1,

zerver/tests/test_events.py

@@ -101,6 +101,7 @@ from zerver.lib.actions import (
     try_add_realm_custom_profile_field,
     try_update_realm_custom_profile_field,
 )
+from zerver.lib.drafts import do_create_drafts, do_delete_draft, do_edit_draft
 from zerver.lib.event_schema import (
     check_alert_words,
     check_attachment_add,
@@ -2308,6 +2309,45 @@ class DraftActionTest(BaseAction):
     def do_disable_drafts_synchronization(self, user_profile: UserProfile) -> None:
         do_set_user_display_setting(user_profile, "enable_drafts_synchronization", False)
 
+    def test_draft_create_event(self) -> None:
+        self.do_enable_drafts_synchronization(self.user_profile)
+        dummy_draft = {
+            "type": "draft",
+            "to": "",
+            "topic": "",
+            "content": "Sample draft content",
+            "timestamp": 1596820995,
+        }
+        action = lambda: do_create_drafts([dummy_draft], self.user_profile)
+        self.verify_action(action)
+
+    def test_draft_edit_event(self) -> None:
+        self.do_enable_drafts_synchronization(self.user_profile)
+        dummy_draft = {
+            "type": "draft",
+            "to": "",
+            "topic": "",
+            "content": "Sample draft content",
+            "timestamp": 1596820995,
+        }
+        draft_id = do_create_drafts([dummy_draft], self.user_profile)[0].id
+        dummy_draft["content"] = "Some more sample draft content"
+        action = lambda: do_edit_draft(draft_id, dummy_draft, self.user_profile)
+        self.verify_action(action)
+
+    def test_draft_delete_event(self) -> None:
+        self.do_enable_drafts_synchronization(self.user_profile)
+        dummy_draft = {
+            "type": "draft",
+            "to": "",
+            "topic": "",
+            "content": "Sample draft content",
+            "timestamp": 1596820995,
+        }
+        draft_id = do_create_drafts([dummy_draft], self.user_profile)[0].id
+        action = lambda: do_delete_draft(draft_id, self.user_profile)
+        self.verify_action(action)
+
     def test_enable_syncing_drafts(self) -> None:
         self.do_disable_drafts_synchronization(self.user_profile)
         action = lambda: self.do_enable_drafts_synchronization(self.user_profile)

zerver/tests/test_home.py

@@ -24,6 +24,7 @@ from zerver.lib.test_classes import ZulipTestCase
 from zerver.lib.test_helpers import get_user_messages, queries_captured
 from zerver.models import (
     DefaultStream,
+    Draft,
     Realm,
     UserActivity,
     UserProfile,
@@ -64,6 +65,7 @@ class HomeTest(ZulipTestCase):
         "dense_mode",
         "desktop_icon_count_display",
         "development_environment",
+        "drafts",
         "email",
         "email_notifications_batching_period_seconds",
         "emojiset",
@@ -271,7 +273,7 @@ class HomeTest(ZulipTestCase):
             set(result["Cache-Control"].split(", ")), {"must-revalidate", "no-store", "no-cache"}
         )
 
-        self.assert_length(queries, 42)
+        self.assert_length(queries, 43)
         self.assert_length(cache_mock.call_args_list, 5)
 
         html = result.content.decode("utf-8")
@@ -351,7 +353,7 @@ class HomeTest(ZulipTestCase):
                 result = self._get_home_page()
                 self.check_rendered_logged_in_app(result)
                 self.assert_length(cache_mock.call_args_list, 6)
-            self.assert_length(queries, 39)
+            self.assert_length(queries, 40)
 
     def test_num_queries_with_streams(self) -> None:
         main_user = self.example_user("hamlet")
@@ -382,7 +384,7 @@ class HomeTest(ZulipTestCase):
         with queries_captured() as queries2:
             result = self._get_home_page()
 
-        self.assert_length(queries2, 37)
+        self.assert_length(queries2, 38)
 
         # Do a sanity check that our new streams were in the payload.
         html = result.content.decode("utf-8")
@@ -1041,3 +1043,35 @@ class HomeTest(ZulipTestCase):
 
         page_params = self._get_page_params(result)
         self.assertEqual(page_params["default_language"], "es")
+
+    @override_settings(MAX_DRAFTS_IN_REGISTER_RESPONSE=5)
+    def test_limit_drafts(self) -> None:
+        draft_objects = []
+        hamlet = self.example_user("hamlet")
+        base_time = timezone_now()
+
+        step_value = timedelta(seconds=1)
+        # Create 11 drafts.
+        for i in range(0, settings.MAX_DRAFTS_IN_REGISTER_RESPONSE + 1):
+            draft_objects.append(
+                Draft(
+                    user_profile=hamlet,
+                    recipient=None,
+                    topic="",
+                    content="sample draft",
+                    last_edit_time=base_time + i * step_value,
+                )
+            )
+        Draft.objects.bulk_create(draft_objects)
+
+        # Now fetch the drafts part of the initial state and make sure
+        # that we only got back settings.MAX_DRAFTS_IN_REGISTER_RESPONSE.
+        # No more. Also make sure that the drafts returned are the most
+        # recently edited ones.
+        self.login("hamlet")
+        page_params = self._get_page_params(self._get_home_page())
+        self.assertEqual(page_params["enable_drafts_synchronization"], True)
+        self.assert_length(page_params["drafts"], settings.MAX_DRAFTS_IN_REGISTER_RESPONSE)
+        self.assertEqual(Draft.objects.count(), settings.MAX_DRAFTS_IN_REGISTER_RESPONSE + 1)
+        for draft in page_params["drafts"]:
+            self.assertNotEqual(draft["timestamp"], base_time)

zproject/default_settings.py

@@ -455,3 +455,8 @@ OUTGOING_WEBHOOK_TIMEOUT_SECONDS = 10
 # Any message content exceeding this limit will be truncated.
 # See: `_internal_prep_message` function in zerver/lib/actions.py.
 MAX_MESSAGE_LENGTH = 10000
+
+# The maximum number of drafts to send in the response to /register.
+# More drafts, should they exist for some crazy reason, could be
+# fetched in a separate request.
+MAX_DRAFTS_IN_REGISTER_RESPONSE = 1000