attachments: Stop fetching attachments in / endpoint.

We only use this data in a rarely-used settings screen, and it can be
large after years of posting screenshots.

So optimize the performance of / by just loading these data when we
actually visit the page.

This saves about 300ms of runtime for loading the home view for my
user account on chat.zulip.org.

static/js/attachments_ui.js

@@ -33,10 +33,8 @@ function bytes_to_size(bytes, kb_with_1024_bytes) {
     return size + ' ' + sizes[i];
  }
 
-exports.set_up_attachments = function () {
-    // The settings page must be rendered before this function gets called.
 
-    var attachments = page_params.attachments;
+function render_attachments_ui(attachments) {
     _.each(attachments, function (attachment) {
         var time = new XDate(attachment.create_time);
         attachment.create_time_str = timerender.render_now(time).time_str;
@@ -78,8 +76,6 @@ exports.set_up_attachments = function () {
         return -1;
     });
 
-
-
     ui.set_up_scrollbar(uploaded_files_table.closest(".progressive-table-wrapper"));
 
     uploaded_files_table.empty();
@@ -93,6 +89,26 @@ exports.set_up_attachments = function () {
         row.remove();
         delete_attachments($(this).data('attachment'));
     });
+}
+
+exports.set_up_attachments = function () {
+    // The settings page must be rendered before this function gets called.
+
+    var status = $('#delete-upload-status');
+    loading.make_indicator($('#attachments_loading_indicator'), {text: 'Loading...'});
+
+    channel.get({
+        url: "/json/attachments",
+        idempotent: true,
+        success: function (data) {
+            loading.destroy_indicator($('#attachments_loading_indicator'));
+            render_attachments_ui(data.attachments);
+        },
+        error: function (xhr) {
+            loading.destroy_indicator($('#attachments_loading_indicator'));
+            ui_report.error(i18n.t("Failed"), xhr, status);
+        },
+    });
 };
 
 return exports;

static/styles/zulip.scss

@@ -2042,6 +2042,7 @@ div.floating_recipient {
 }
 
 .settings-section #admin_page_users_loading_indicator,
+.settings-section #attachments_loading_indicator,
 .settings-section #admin_page_deactivated_users_loading_indicator,
 .settings-section #admin_page_bots_loading_indicator {
     margin: 0 auto;

static/templates/settings/attachments-settings.handlebars

@@ -17,4 +17,5 @@
               id="uploaded_files_table" ></tbody>
         </table>
     </div>
+    <div id="attachments_loading_indicator"></div>
 </div>

zerver/lib/events.py

@@ -125,9 +125,6 @@ def fetch_initial_state_data(user_profile: UserProfile,
         state['custom_profile_fields'] = [f.as_dict() for f in fields]
         state['custom_profile_field_types'] = CustomProfileField.FIELD_TYPE_CHOICES
 
-    if want('attachments'):
-        state['attachments'] = user_attachments(user_profile)
-
     if want('hotspots'):
         state['hotspots'] = get_next_hotspots(user_profile)
 

zerver/tests/test_events.py

@@ -2803,11 +2803,10 @@ class FetchQueriesTest(ZulipTestCase):
                     client_gravatar=False,
                 )
 
-        self.assert_length(queries, 30)
+        self.assert_length(queries, 29)
 
         expected_counts = dict(
             alert_words=0,
-            attachments=1,
             custom_profile_fields=1,
             default_streams=1,
             default_stream_groups=1,

zerver/tests/test_home.py

@@ -45,7 +45,6 @@ class HomeTest(ZulipTestCase):
         # Keep this list sorted!!!
         expected_keys = [
             "alert_words",
-            "attachments",
             "avatar_source",
             "avatar_url",
             "avatar_url_medium",
@@ -198,7 +197,7 @@ class HomeTest(ZulipTestCase):
             with patch('zerver.lib.cache.cache_set') as cache_mock:
                 result = self._get_home_page(stream='Denmark')
 
-        self.assert_length(queries, 42)
+        self.assert_length(queries, 41)
         self.assert_length(cache_mock.call_args_list, 7)
 
         html = result.content.decode('utf-8')
@@ -242,7 +241,7 @@ class HomeTest(ZulipTestCase):
                 result = self._get_home_page()
                 self.assertEqual(result.status_code, 200)
                 self.assert_length(cache_mock.call_args_list, 6)
-            self.assert_length(queries, 39)
+            self.assert_length(queries, 37)
 
     @slow("Creates and subscribes 10 users in a loop.  Should use bulk queries.")
     def test_num_queries_with_streams(self) -> None:
@@ -274,7 +273,7 @@ class HomeTest(ZulipTestCase):
         with queries_captured() as queries2:
             result = self._get_home_page()
 
-        self.assert_length(queries2, 36)
+        self.assert_length(queries2, 35)
 
         # Do a sanity check that our new streams were in the payload.
         html = result.content.decode('utf-8')