add poolclass awareness to engine_from_config()

edbob/db/__init__.py

@@ -28,11 +28,12 @@
 
 from __future__ import absolute_import
 
-from sqlalchemy import engine_from_config, MetaData
+from sqlalchemy import MetaData
 from sqlalchemy.orm import sessionmaker
 from sqlalchemy.ext.declarative import declarative_base
 
 import edbob
+from edbob.sqlalchemy import engine_from_config
 
 
 __all__ = ['engines', 'engine', 'Session', 'get_setting', 'save_setting']

edbob/sqlalchemy.py

@@ -29,14 +29,51 @@
 from __future__ import absolute_import
 
 from sqlalchemy import Table, Column, String
+from sqlalchemy import engine_from_config as _engine_from_config
 
 from edbob.core import get_uuid
+from edbob.modules import load_spec
 from edbob.time import utc_time
 
 
 __all__ = ['getset_factory', 'table_with_uuid', 'current_time']
 
 
+def current_time(context):
+    """
+    This function may be provided to the ``default`` parameter of a
+    :class:`sqlalchemy.Column` class definition.  Doing so will ensure the
+    column's default value will be the current time in UTC.
+    """
+
+    return utc_time(naive=True)
+
+
+def engine_from_config(config, prefix='sqlalchemy.', **kwargs):
+    """
+    Slightly enhanced version of the :func:`sqlalchemy.engine_from_config()`
+    function.  This version is aware of the ``poolclass`` configuration
+    parameter, and will coerce it via :func:`edbob.load_spec()`.
+
+    Note that if a pool class is specified, the class should be represented
+    using the "spec" format and *not* pure dotted path notation, e.g.:
+
+    Correct::
+
+       [edbob.db]
+       default.poolclass = sqlqlchemy.pool:NullPool
+
+    Incorrect::
+
+       [edbob.db]
+       default.poolclass = sqlalchemy.pool.NullPool
+    """
+
+    if config.has_key(prefix + 'poolclass'):
+        config[prefix + 'poolclass'] = load_spec(config[prefix + 'poolclass'])
+    return _engine_from_config(config, prefix=prefix, **kwargs)
+
+
 def getset_factory(collection_class, proxy):
     """
     Get/set factory for SQLAlchemy association proxy attributes.
@@ -77,13 +114,3 @@ def table_with_uuid(name, metadata, *args, **kwargs):
     return Table(name, metadata,
                  Column('uuid', String(32), primary_key=True, default=get_uuid),
                  *args, **kwargs)
-
-
-def current_time(context):
-    """
-    This function may be provided to the ``default`` parameter of a
-    :class:`sqlalchemy.Column` class definition.  Doing so will ensure the
-    column's default value will be the current time in UTC.
-    """
-
-    return utc_time(naive=True)