[IMP] mail: turn 'Message/shorttime' into field

Task-2793280

closes odoo/odoo#86459

Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

addons/mail/static/src/components/message/message.js

@@ -230,15 +230,6 @@ export class Message extends Component {
         }
     }
 
-    /**
-     * Get the shorttime format of the message date.
-     *
-     * @returns {string}
-     */
-    get shortTime() {
-        return this.messageView.message.date.format('hh:mm');
-    }
-
     //--------------------------------------------------------------------------
     // Private
     //--------------------------------------------------------------------------

addons/mail/static/src/components/message/message.xml

@@ -46,7 +46,7 @@
                         <t t-else="">
                             <t t-if="isActive and messageView.message.date">
                                 <div class="o_Message_date o_Message_sidebarItem mt-1" t-att-class="{ 'o-message-selected': isSelected }">
-                                    <t t-esc="shortTime"/>
+                                    <t t-esc="messageView.message.shortTime"/>
                                 </div>
                             </t>
                             <t t-if="!isActive and messageView.message.isCurrentUserOrGuestAuthor and messageView.threadView and messageView.threadView.thread and messageView.threadView.thread.hasSeenIndicators">

addons/mail/static/src/models/message.js

@@ -555,6 +555,16 @@ registerModel({
             // add anchor tags to urls
             return parseAndTransform(prettyBody, addLink);
         },
+        /**
+         * @private
+         * @returns {string|FieldCommand}
+         */
+        _computeShortTime() {
+            if (!this.date) {
+                return clear();
+            }
+            return this.date.format('hh:mm');
+        },
         /**
          * @private
          * @returns {Thread[]}
@@ -878,6 +888,9 @@ registerModel({
             default: "",
         }),
         recipients: many('Partner'),
+        shortTime: attr({
+            compute: '_computeShortTime',
+        }),
         subject: attr(),
         subtype_description: attr(),
         subtype_id: attr(),