attachments: Send events for attachment updates.

We send add events on upload, update events when sending a message
referencing it, and delete updates on removal.

This should make it possible to do real-time sync for the attachments
UI.

Based in part on work by Aastha Gupta.

static/js/server_events_dispatch.js

@@ -10,6 +10,10 @@ exports.dispatch_normal_event = function dispatch_normal_event(event) {
         alert_words_ui.render_alert_words_ui();
         break;
 
+    case 'attachment':
+        // Do nothing for now.
+        break;
+
     case 'default_streams':
         stream_data.set_realm_default_streams(event.default_streams);
         settings_streams.update_default_streams_table();

zerver/lib/actions.py

@@ -4516,6 +4516,15 @@ def do_get_streams(user_profile: UserProfile, include_public: bool=True,
 
     return streams
 
+def notify_attachment_update(user_profile: UserProfile, op: str,
+                             attachment_dict: Dict[str, Any]) -> None:
+    event = {
+        'type': 'attachment',
+        'op': op,
+        'attachment': attachment_dict,
+    }
+    send_event(event, [user_profile.id])
+
 def do_claim_attachments(message: Message) -> None:
     attachment_url_list = attachment_url_re.findall(message.content)
 
@@ -4540,7 +4549,8 @@ def do_claim_attachments(message: Message) -> None:
                 user_profile.id, path_id, message.id))
             continue
 
-        claim_attachment(user_profile, path_id, message, is_message_realm_public)
+        attachment = claim_attachment(user_profile, path_id, message, is_message_realm_public)
+        notify_attachment_update(user_profile, "update", attachment.to_dict())
 
 def do_delete_old_unclaimed_attachments(weeks_ago: int) -> None:
     old_unclaimed_attachments = get_old_unclaimed_attachments(weeks_ago)

zerver/lib/events.py

@@ -560,6 +560,10 @@ def apply_event(state: Dict[str, Any],
     elif event['type'] == 'typing':
         # Typing notification events are transient and thus ignored
         pass
+    elif event['type'] == "attachment":
+        # Attachment events are just for updating the "uploads" UI;
+        # they are not sent directly.
+        pass
     elif event['type'] == "update_message_flags":
         # We don't return messages in `/register`, so most flags we
         # can ignore, but we do need to update the unread_msgs data if

zerver/lib/upload.py

@@ -540,16 +540,19 @@ def upload_message_file(uploaded_file_name: Text, uploaded_file_size: int,
 def claim_attachment(user_profile: UserProfile,
                      path_id: Text,
                      message: Message,
-                     is_message_realm_public: bool) -> None:
+                     is_message_realm_public: bool) -> Attachment:
     attachment = Attachment.objects.get(path_id=path_id)
     attachment.messages.add(message)
     attachment.is_realm_public = attachment.is_realm_public or is_message_realm_public
     attachment.save()
+    return attachment
 
 def create_attachment(file_name: Text, path_id: Text, user_profile: UserProfile,
                       file_size: int) -> bool:
-    Attachment.objects.create(file_name=file_name, path_id=path_id, owner=user_profile,
-                              realm=user_profile.realm, size=file_size)
+    attachment = Attachment.objects.create(file_name=file_name, path_id=path_id, owner=user_profile,
+                                           realm=user_profile.realm, size=file_size)
+    from zerver.lib.actions import notify_attachment_update
+    notify_attachment_update(user_profile, 'add', attachment.to_dict())
     return True
 
 def upload_message_image_from_request(request: HttpRequest, user_file: File,

zerver/tests/test_events.py

@@ -10,11 +10,13 @@ from django.conf import settings
 from django.http import HttpRequest, HttpResponse
 from django.test import TestCase
 from django.utils.timezone import now as timezone_now
+from io import StringIO
 
 from zerver.models import (
     get_client, get_realm, get_stream_recipient, get_stream, get_user,
     Message, RealmDomain, Recipient, UserMessage, UserPresence, UserProfile,
     Realm, Subscription, Stream, flush_per_request_caches, UserGroup, Service,
+    Attachment,
 )
 
 from zerver.lib.actions import (
@@ -79,6 +81,7 @@ from zerver.lib.actions import (
     do_update_user_presence,
     log_event,
     lookup_default_stream_groups,
+    notify_attachment_update,
     notify_realm_custom_profile_fields,
     check_add_user_group,
     do_update_user_group_name,
@@ -110,6 +113,7 @@ from zerver.lib.validator import (
     check_bool, check_dict, check_dict_only, check_float, check_int, check_list, check_string,
     equals, check_none_or, Validator, check_url
 )
+from zerver.lib.upload import upload_backend, attachment_url_to_path_id
 
 from zerver.views.events_register import _default_all_public_streams, _default_narrow
 from zerver.views.users import add_service
@@ -2096,6 +2100,88 @@ class EventsRegisterTest(ZulipTestCase):
         result = fetch_initial_state_data(user_profile, None, "", client_gravatar=False)
         self.assertEqual(result['max_message_id'], -1)
 
+    def test_add_attachment(self) -> None:
+        schema_checker = self.check_events_dict([
+            ('type', equals('attachment')),
+            ('op', equals('add')),
+            ('attachment', check_dict_only([
+                ('id', check_int),
+                ('name', check_string),
+                ('size', check_int),
+                ('path_id', check_string),
+                ('create_time', check_float),
+                ('messages', check_list(check_dict_only([
+                    ('id', check_int),
+                    ('name', check_float),
+                ]))),
+            ])),
+        ])
+
+        self.login(self.example_email("hamlet"))
+        fp = StringIO("zulip!")
+        fp.name = "zulip.txt"
+        data = {'uri': None}
+
+        def do_upload() -> None:
+            result = self.client_post("/json/user_uploads", {'file': fp})
+
+            self.assert_json_success(result)
+            self.assertIn("uri", result.json())
+            uri = result.json()["uri"]
+            base = '/user_uploads/'
+            self.assertEqual(base, uri[:len(base)])
+            data['uri'] = uri
+
+        events = self.do_test(
+            lambda: do_upload(),
+            num_events=1, state_change_expected=False)
+        error = schema_checker('events[0]', events[0])
+        self.assert_on_error(error)
+
+        # Verify that the DB has the attachment marked as unclaimed
+        entry = Attachment.objects.get(file_name='zulip.txt')
+        self.assertEqual(entry.is_claimed(), False)
+
+        # Now we send an actual message using this attachment.
+        schema_checker = self.check_events_dict([
+            ('type', equals('attachment')),
+            ('op', equals('update')),
+            ('attachment', check_dict_only([
+                ('id', check_int),
+                ('name', check_string),
+                ('size', check_int),
+                ('path_id', check_string),
+                ('create_time', check_float),
+                ('messages', check_list(check_dict_only([
+                    ('id', check_int),
+                    ('name', check_float),
+                ]))),
+            ])),
+        ])
+
+        self.subscribe(self.example_user("hamlet"), "Denmark")
+        body = "First message ...[zulip.txt](http://localhost:9991" + data['uri'] + ")"
+        events = self.do_test(
+            lambda: self.send_stream_message(self.example_email("hamlet"), "Denmark", body, "test"),
+            num_events=2)
+        error = schema_checker('events[0]', events[0])
+        self.assert_on_error(error)
+
+        # Now remove the attachment
+        schema_checker = self.check_events_dict([
+            ('type', equals('attachment')),
+            ('op', equals('remove')),
+            ('attachment', check_dict_only([
+                ('id', check_int),
+            ])),
+        ])
+
+        events = self.do_test(
+            lambda: self.client_delete("/json/attachments/%s" % (entry.id,)),
+            num_events=1, state_change_expected=False)
+        error = schema_checker('events[0]', events[0])
+        self.assert_on_error(error)
+
 class FetchInitialStateDataTest(ZulipTestCase):
     # Non-admin users don't have access to all bots
     def test_realm_bots_non_admin(self) -> None:

zerver/views/attachments.py

@@ -1,6 +1,7 @@
 from django.http import HttpRequest, HttpResponse
 
 from zerver.models import UserProfile
+from zerver.lib.actions import notify_attachment_update
 from zerver.lib.validator import check_int
 from zerver.lib.response import json_success
 from zerver.lib.attachments import user_attachments, remove_attachment, \
@@ -14,5 +15,6 @@ def list_by_user(request: HttpRequest, user_profile: UserProfile) -> HttpRespons
 def remove(request: HttpRequest, user_profile: UserProfile, attachment_id: int) -> HttpResponse:
     attachment = access_attachment_by_id(user_profile, attachment_id,
                                          needs_owner=True)
+    notify_attachment_update(user_profile, "remove", {"id": attachment.id})
     remove_attachment(user_profile, attachment)
     return json_success()