Database docs also cleaned up postgres isolation level handling.

docs/peewee/api.rst

@@ -620,8 +620,7 @@ Database
     :param bool register_unicode: Register unicode types.
     :param str encoding: Database encoding.
     :param int isolation_level: Isolation level constant, defined in the
-        ``psycopg2.extensions`` module or ``psycopg.connection.IsolationLevel``
-        enum (psycopg3).
+        ``psycopg2.extensions`` module or ``psycopg.IsolationLevel`` enum (psycopg3).
     :param bool prefer_psycopg3: If both psycopg2 and psycopg3 are installed,
         instruct Peewee to prefer psycopg3.
 
@@ -633,21 +632,29 @@ Database
         Set the timezone on the current connection. If no connection is open,
         then one will be opened.
 
+    .. py:method:: set_isolation_level(isolation_level)
+
+       :param int isolation_level: Isolation level constant, defined in the
+           ``psycopg2.extensions`` module or ``psycopg.IsolationLevel`` enum (psycopg3).
+           Set to ``None`` to use the server default.
+
     .. py:method:: atomic(isolation_level=None)
 
-        :param str isolation_level: Isolation strategy: SERIALIZABLE, READ COMMITTED, REPEATABLE READ, READ UNCOMMITTED
+        :param isolation_level: Isolation strategy: SERIALIZABLE, READ COMMITTED, REPEATABLE READ, READ UNCOMMITTED
+        :type isolation_level: ``int`` or ``str``.
 
         Create an atomic context-manager, optionally using the specified
-        isolation level (if unspecified, the server default will be used).
+        isolation level (if unspecified, the connection default will be used).
 
         .. note:: Isolation level only applies to the outermost ``atomic()`` block.
 
     .. py:method:: transaction(isolation_level=None)
 
-        :param str isolation_level: Isolation strategy: SERIALIZABLE, READ COMMITTED, REPEATABLE READ, READ UNCOMMITTED
+        :param isolation_level: Isolation strategy: SERIALIZABLE, READ COMMITTED, REPEATABLE READ, READ UNCOMMITTED
+        :type isolation_level: ``int`` or ``str``.
 
         Create a transaction context-manager, optionally using the specified
-        isolation level (if unspecified, the server default will be used).
+        isolation level (if unspecified, the connection default will be used).
 
 
 .. py:class:: MySQLDatabase(database, **kwargs)

peewee.py

@@ -3946,8 +3946,34 @@ class SqliteDatabase(Database):
         return fn.datetime(date_field, 'unixepoch')
 
 
-class Psycopg2Adapter(object):
+class _BasePsycopgAdapter(object):
+    isolation_levels = {}  # Map int -> str.
+
     def __init__(self):
+        self.isolation_levels_inv = {
+            v: k for k, v in self.isolation_levels.items()}
+
+    def isolation_level_int(self, isolation_level):
+        if isinstance(isolation_level, str):
+            return self.isolation_levels_inv[isolation_level]
+        return isolation_level
+
+    def isolation_level_str(self, isolation_level):
+        if isinstance(isolation_level, int):
+            return self.isolation_levels[isolation_level]
+        return isolation_level
+
+
+class Psycopg2Adapter(_BasePsycopgAdapter):
+    isolation_levels = {
+        1: 'READ COMMITTED',
+        2: 'REPEATABLE READ',
+        3: 'SERIALIZABLE',
+        4: 'READ UNCOMMITTED',
+    }
+
+    def __init__(self):
+        super(Psycopg2Adapter, self).__init__()
         self.json_type = Json_pg2
         self.jsonb_type = Json_pg2
         self.cast_json_case = True
@@ -4005,8 +4031,16 @@ class Psycopg2Adapter(object):
         return fn.EXTRACT(NodeList((date_part, SQL('FROM'), date_field)))
 
 
-class Psycopg3Adapter(object):
+class Psycopg3Adapter(_BasePsycopgAdapter):
+    isolation_levels = {
+        1: 'READ UNCOMMITTED',
+        2: 'READ COMMITTED',
+        3: 'REPEATABLE READ',
+        4: 'SERIALIZABLE',
+    }
+
     def __init__(self):
+        super(Psycopg3Adapter, self).__init__()
         self.json_type = Json_pg3
         self.jsonb_type = Jsonb_pg3
         self.cast_json_case = False
@@ -4084,7 +4118,6 @@ class PostgresqlDatabase(Database):
              isolation_level=None, **kwargs):
         self._register_unicode = register_unicode
         self._encoding = encoding
-        self._isolation_level = isolation_level
 
         prefer_psycopg3 = kwargs.pop('prefer_psycopg3', False)
         if psycopg is not None and prefer_psycopg3:
@@ -4092,6 +4125,11 @@ class PostgresqlDatabase(Database):
         else:
             self._adapter = self.psycopg2_adapter()
 
+        # Accept a string ('READ COMMITTED') or an int constant. Since the
+        # constants vary between psycopg2 & psycopg3 we have to abstract this.
+        self._isolation_level = self._adapter.isolation_level_int(
+            isolation_level)
+
         super(PostgresqlDatabase, self).init(database, **kwargs)
 
     def _connect(self):
@@ -4137,7 +4175,8 @@ class PostgresqlDatabase(Database):
         if self.is_closed():
             self.connect()
         if isolation_level:
-            stmt = 'BEGIN TRANSACTION ISOLATION LEVEL %s' % isolation_level
+            txn_type = self._adapter.isolation_level_str(isolation_level)
+            stmt = 'BEGIN TRANSACTION ISOLATION LEVEL %s' % txn_type
         else:
             stmt = 'BEGIN'
         with __exception_wrapper__:
@@ -4282,6 +4321,10 @@ class PostgresqlDatabase(Database):
     def set_time_zone(self, timezone):
         self.execute_sql('set time zone "%s";' % timezone)
 
+    def set_isolation_level(self, isolation_level):
+        self._isolation_level = self._adapter.isolation_level_int(
+            isolation_level)
+
 
 class MySQLDatabase(Database):
     field_types = {

playhouse/db_url.py

@@ -9,9 +9,11 @@ from playhouse.cockroachdb import PooledCockroachDatabase
 from playhouse.pool import PooledCySqliteDatabase
 from playhouse.pool import PooledMySQLDatabase
 from playhouse.pool import PooledPostgresqlDatabase
+from playhouse.pool import PooledPostgresqlExtDatabase
 from playhouse.pool import PooledPsycopg3Database
 from playhouse.pool import PooledSqliteDatabase
 from playhouse.pool import PooledSqliteExtDatabase
+from playhouse.postgres_ext import PostgresqlExtDatabase
 from playhouse.postgres_ext import Psycopg3Database
 from playhouse.sqlite_ext import SqliteExtDatabase
 try:
@@ -31,6 +33,10 @@ schemes = {
     'postgresql': PostgresqlDatabase,
     'postgres+pool': PooledPostgresqlDatabase,
     'postgresql+pool': PooledPostgresqlDatabase,
+    'postgresext': PostgresqlExtDatabase,
+    'postgresqlext': PostgresqlExtDatabase,
+    'postgresext+pool': PooledPostgresqlExtDatabase,
+    'postgresqlext+pool': PooledPostgresqlExtDatabase,
     'psycopg3': Psycopg3Database,
     'psycopg3+pool': PooledPsycopg3Database,
     'sqlite': SqliteDatabase,
@@ -38,11 +44,6 @@ schemes = {
     'sqlite+pool': PooledSqliteDatabase,
     'sqliteext+pool': PooledSqliteExtDatabase,
 }
-if CySqliteDatabase is not None:
-    schemes.update({
-        'cysqlite': CySqliteDatabase,
-        'cysqlite+pool': PooledCySqliteDatabase,
-    })
 
 def register_database(db_class, *names):
     global schemes
@@ -136,8 +137,9 @@ else:
     register_database(APSWDatabase, 'apsw')
 
 try:
-    from playhouse.postgres_ext import PostgresqlExtDatabase
+    from playhouse.cysqlite_ext import CySqliteDatabase
 except ImportError:
     pass
 else:
-    register_database(PostgresqlExtDatabase, 'postgresext', 'postgresqlext')
+    register_database(CySqliteDatabase, 'cysqlite')
+    register_database(PooledCySqliteDatabase, 'cysqlite+pool')

tests/postgres.py

@@ -872,10 +872,30 @@ class TestPostgresIsolationLevel(DatabaseTestCase):
 
         conn.set_isolation_level(2)
         self.assertEqual(conn.isolation_level, 2)
-
         self.database.close()
+
         conn = self.database.connection()
         self.assertEqual(conn.isolation_level, 3)
+        self.database.close()
+
+        self.database.set_isolation_level(2)
+        for _ in range(2):
+            conn = self.database.connection()
+            self.assertEqual(conn.isolation_level, 2)
+            self.database.close()
+
+    def test_isolation_level_str(self):
+        db = db_loader('postgres', isolation_level='SERIALIZABLE')
+        conn = db.connection()
+        self.assertEqual(conn.isolation_level,
+                         db._adapter.isolation_levels_inv['SERIALIZABLE'])
+        db.close()
+
+        db.set_isolation_level('READ COMMITTED')
+        conn = db.connection()
+        self.assertEqual(conn.isolation_level,
+                         db._adapter.isolation_levels_inv['READ COMMITTED'])
+        db.close()
 
 
 @skip_unless(pg12(), 'cte materialization requires pg >= 12')