add mentions

app/migrations.py

@@ -22,6 +22,18 @@ def create_default_bookmark_collections():
     for user in user_ids_without_default_collection:
         BookmarkCollections.create_default(user['id'])
 
+def add_display_name():
+    dq = 'ALTER TABLE "users" ADD COLUMN "display_name" TEXT NOT NULL DEFAULT ""'
+    db.execute(dq)
+    from .models import Users
+    for user in Users.select():
+        data = {
+            'username': user.username.lower(),
+        }
+        if user.username.lower() != user.username:
+            data['display_name'] = user.username
+        user.update(data)
+
 # format: [str|tuple(str, any...)|callable]
 MIGRATIONS = [
     migrate_old_avatars,
@@ -30,6 +42,7 @@ MIGRATIONS = [
     'ALTER TABLE "post_history" ADD COLUMN "format_version" INTEGER DEFAULT NULL',
     add_signature_format,
     create_default_bookmark_collections,
+    add_display_name,
 ]
 
 def run_migrations():