rebase and fixed issues

CHANGELOG.rst

@@ -23,6 +23,7 @@ Fixed
 ^^^^^
 - Fix `DatetimeField` use '__year' report `'int' object has no attribute 'utcoffset'`. (#1575)
 - Fix `bulk_update` when using custom fields. (#1564)
+- Fix `get_or_create` method. (#1404)
 
 0.20.1
 ------

tortoise/models.py

@@ -32,7 +32,6 @@
     IntegrityError,
     OperationalError,
     ParamsError,
-    TransactionManagementError,
 )
 from tortoise.fields.base import Field
 from tortoise.fields.data import IntField
@@ -1068,7 +1067,6 @@ async def get_or_create(
         :param using_db: Specific DB connection to use instead of default bound
         :param kwargs: Query parameters.
         :raises IntegrityError: If create failed
-        :raises TransactionManagementError: If transaction error
         """
         if not defaults:
             defaults = {}
@@ -1077,13 +1075,13 @@ async def get_or_create(
             return await cls.filter(**kwargs).using_db(db).get(), False
         except DoesNotExist:
             try:
-                async with in_transaction(connection_name=db.connection_name) as connection:
-                    return await cls.create(using_db=connection, **defaults, **kwargs), True
-            except (IntegrityError, TransactionManagementError) as exc:
+                return await cls.create(using_db=db, **defaults, **kwargs), True
+            except IntegrityError as exc:
                 try:
                     return await cls.filter(**kwargs).using_db(db).get(), False
-                except Exception:
-                    raise exc
+                except DoesNotExist:
+                    pass
+                raise exc
 
     @classmethod
     def select_for_update(