handle the case pg_trgm is already loaded

migrations/versions/2021_082012_424808e1fe49_.py

@@ -8,7 +8,8 @@ Create Date: 2021-08-20 12:11:57.901994
 import sqlalchemy_utils
 from alembic import op
 import sqlalchemy as sa
-
+from psycopg2 import errors
+from psycopg2.errorcodes import DUPLICATE_OBJECT
 
 # revision identifiers, used by Alembic.
 revision = '424808e1fe49'
@@ -19,7 +20,14 @@ depends_on = None
 
 def upgrade():
     # ### commands auto generated by Alembic - please adjust! ###
-    op.execute('CREATE EXTENSION pg_trgm')
+    try:
+        op.execute('CREATE EXTENSION pg_trgm')
+    # thanks to https://stackoverflow.com/a/58743364/1428034 !
+    except sa.exc.ProgrammingError as e:
+        if isinstance(e.orig, errors.lookup(DUPLICATE_OBJECT)):
+            print(">>> pg_trgm already loaded, ignore")
+            op.execute("Rollback")
+
     op.create_index('note_pg_trgm_index', 'alias', ['note'], unique=False, postgresql_ops={'note': 'gin_trgm_ops'}, postgresql_using='gin')
     # ### end Alembic commands ###