Add make_engine_from_config() method for AppHandler

and other misc. tweaks needed to get this incorporated into Rattail

src/wuttjamaican/app.py

@@ -24,7 +24,7 @@
 WuttJamaican - app handler
 """
 
-from wuttjamaican.util import load_entry_points
+from wuttjamaican.util import load_entry_points, load_object, parse_bool
 
 
 class AppHandler:
@@ -47,6 +47,60 @@ class AppHandler:
         self.config = config
         self.handlers = {}
 
+    def make_engine_from_config(
+            self,
+            config_dict,
+            prefix='sqlalchemy.',
+            **kwargs):
+        """
+        Construct a new DB engine from configuration dict.
+
+        This is a wrapper around upstream
+        :func:`sqlalchemy:sqlalchemy.engine_from_config()`.
+
+        The purpose of the customization is to allow certain
+        attributes of the engine to be driven by config, whereas the
+        upstream function is more limited in that regard.  The
+        following in particular:
+
+        * ``poolclass``
+        * ``pool_pre_ping``
+
+        If these options are present in the configuration dict, they
+        will be coerced to appropriate Python equivalents and then
+        passed as kwargs to the upstream function.
+
+        An example config file leveraging this feature:
+
+        .. code-block:: ini
+
+           [wutta.db]
+           default.url = sqlite:///tmp/default.sqlite
+           default.poolclass = sqlalchemy.pool:NullPool
+           default.pool_pre_ping = true
+
+        Note that if present, the ``poolclass`` value must be a "spec"
+        string, as required by
+        :func:`~wuttjamaican.util.load_object()`.
+        """
+        import sqlalchemy as sa
+
+        config_dict = dict(config_dict)
+
+        # convert 'poolclass' arg to actual class
+        key = f'{prefix}poolclass'
+        if key in config_dict and 'poolclass' not in kwargs:
+            kwargs['poolclass'] = load_object(config_dict.pop(key))
+
+        # convert 'pool_pre_ping' arg to boolean
+        key = f'{prefix}pool_pre_ping'
+        if key in config_dict and 'pool_pre_ping' not in kwargs:
+            kwargs['pool_pre_ping'] = parse_bool(config_dict.pop(key))
+
+        engine = sa.engine_from_config(config_dict, prefix, **kwargs)
+
+        return engine
+
     def make_session(self, **kwargs):
         """
         Creates a new SQLAlchemy session for the app DB.  By default

src/wuttjamaican/conf.py

@@ -195,6 +195,15 @@ class WuttaConfig:
                 path = path % {'here': here}
                 self._load_ini_configs(path, configs, require=False)
 
+    def get_prioritized_files(self):
+        """
+        Returns list of config files in order of priority.
+
+        By default, :attr:`files_read` should already be in the
+        correct order, but this is to make things more explicit.
+        """
+        return self.files_read
+
     def setdefault(
             self,
             key,
@@ -222,6 +231,7 @@ class WuttaConfig:
             key,
             default=UNSPECIFIED,
             require=False,
+            ignore_ambiguous=False,
             message=None,
             usedb=None,
             preferdb=None,
@@ -283,6 +293,12 @@ class WuttaConfig:
            Note that it is an error to specify a default value if you
            also specify ``require=True``.
 
+        :param ignore_ambiguous: By default this method will log a
+           warning if an ambiguous value is detected (as described
+           above).  Pass a true value for this flag to avoid the
+           warnings.  Should use with caution, as the warnings are
+           there for a reason.
+
         :param message: Optional first part of message to be used,
            when raising a "value not found" error.  If not specified,
            a default error message will be generated.
@@ -329,6 +345,7 @@ class WuttaConfig:
             if not isinstance(value, configuration.Configuration):
                 return value
 
+            if not ignore_ambiguous:
                 log.warning("ambiguous config key '%s' returns: %s", key, value)
 
         # read from db last if so requested
@@ -380,6 +397,29 @@ class WuttaConfig:
         value = self.get(*args, **kwargs)
         return parse_bool(value)
 
+    def get_int(self, *args, **kwargs):
+        """
+        Retrieve an integer value from config.
+
+        Accepts same params as :meth:`get()` but if a value is found,
+        it will be coerced to integer via the :class:`python:int()`
+        constructor.
+        """
+        value = self.get(*args, **kwargs)
+        if value is not None:
+            return int(value)
+
+    def get_list(self, *args, **kwargs):
+        """
+        Retrieve a list value from config.
+
+        Accepts same params as :meth:`get()` but if a value is found,
+        it will be coerced to list via
+        :func:`~wuttjamaican.util.parse_list()`.
+        """
+        value = self.get(*args, **kwargs)
+        return parse_list(value)
+
     def get_dict(self, prefix):
         """
         Retrieve a particular group of values, as a dictionary.

src/wuttjamaican/db/conf.py

@@ -28,56 +28,7 @@ from collections import OrderedDict
 
 import sqlalchemy as sa
 
-from wuttjamaican.util import load_object, parse_bool, parse_list
-
-
-def engine_from_config(configuration, prefix='sqlalchemy.', **kwargs):
-    """
-    Construct a new DB engine from configuration.
-
-    This is a wrapper around upstream
-    :func:`sqlalchemy:sqlalchemy.engine_from_config()`.
-
-    The purpose of the customization is to allow certain attributes of
-    the engine to be driven by config, whereas the upstream function
-    is more limited in that regard.  The following in particular:
-
-    * ``poolclass``
-    * ``pool_pre_ping``
-
-    If these options are present in the configuration dictionary, they
-    will be coerced to appropriate Python equivalents and then passed
-    as kwargs to the upstream function.
-
-    An example config file leveraging this feature:
-
-    .. code-block:: ini
-
-       [wutta.db]
-       sqlalchemy.url = sqlite:///tmp/default.sqlite
-       sqlalchemy.poolclass = sqlalchemy.pool:NullPool
-       sqlalchemy.pool_pre_ping = true
-
-    Note that if present, the ``poolclass`` value must be a "spec"
-    string, as required by :func:`~wuttjamaican.util.load_object()`.
-    """
-    config_dict = dict(configuration)
-
-    # convert 'poolclass' arg to actual class
-    key = f'{prefix}poolclass'
-    if key in config_dict:
-        kwargs.setdefault('poolclass', load_object(config_dict[key]))
-        del config_dict[key]
-
-    # convert 'pool_pre_ping' arg to boolean
-    key = f'{prefix}pool_pre_ping'
-    if key in config_dict:
-        kwargs.setdefault('pool_pre_ping', parse_bool(config_dict[key]))
-        del config_dict[key]
-
-    engine = sa.engine_from_config(config_dict, prefix, **kwargs)
-
-    return engine
+from wuttjamaican.util import parse_list
 
 
 def get_engines(config, prefix):
@@ -111,6 +62,8 @@ def get_engines(config, prefix):
     :returns: A dictionary of SQLAlchemy engines, with keys matching
        those found in config.
     """
+    app = config.get_app()
+
     keys = config.get(f'{prefix}.keys', usedb=False)
     if keys:
         keys = parse_list(keys)
@@ -122,11 +75,11 @@ def get_engines(config, prefix):
     for key in keys:
         key = key.strip()
         try:
-            engines[key] = engine_from_config(cfg, prefix=f'{key}.')
+            engines[key] = app.make_engine_from_config(cfg, prefix=f'{key}.')
         except KeyError:
             if key == 'default':
                 try:
-                    engines[key] = engine_from_config(cfg, prefix='sqlalchemy.')
+                    engines[key] = app.make_engine_from_config(cfg, prefix='sqlalchemy.')
                 except KeyError:
                     pass
     return engines

src/wuttjamaican/util.py

@@ -150,6 +150,8 @@ def parse_list(value):
     """
     if value is None:
         return []
+    if isinstance(value, list):
+        return value
     parser = shlex.shlex(value)
     parser.whitespace += ','
     parser.whitespace_split = True

tests/db/test_conf.py

@@ -7,48 +7,11 @@ from unittest import TestCase
 
 import sqlalchemy as sa
 from sqlalchemy import orm
-from sqlalchemy.engine import Engine
-from sqlalchemy.pool import NullPool
 
 from wuttjamaican.db import conf
 from wuttjamaican.conf import WuttaConfig
 
 
-class TestEngineFromConfig(TestCase):
-
-    def test_basic(self):
-        engine = conf.engine_from_config({
-            'sqlalchemy.url': 'sqlite://',
-        })
-        self.assertIsInstance(engine, Engine)
-
-    def test_poolclass(self):
-
-        engine = conf.engine_from_config({
-            'sqlalchemy.url': 'sqlite://',
-        })
-        self.assertNotIsInstance(engine.pool, NullPool)
-
-        engine = conf.engine_from_config({
-            'sqlalchemy.url': 'sqlite://',
-            'sqlalchemy.poolclass': 'sqlalchemy.pool:NullPool',
-        })
-        self.assertIsInstance(engine.pool, NullPool)
-
-    def test_pool_pre_ping(self):
-
-        engine = conf.engine_from_config({
-            'sqlalchemy.url': 'sqlite://',
-        })
-        self.assertFalse(engine.pool._pre_ping)
-
-        engine = conf.engine_from_config({
-            'sqlalchemy.url': 'sqlite://',
-            'sqlalchemy.pool_pre_ping': 'true',
-        })
-        self.assertTrue(engine.pool._pre_ping)
-
-
 class TestGetEngines(TestCase):
 
     def setUp(self):

tests/test_app.py

@@ -5,6 +5,8 @@ from unittest.mock import patch, MagicMock
 
 import sqlalchemy as sa
 from sqlalchemy import orm
+from sqlalchemy.engine import Engine
+from sqlalchemy.pool import NullPool
 
 from wuttjamaican import app, db
 
@@ -19,6 +21,38 @@ class TestAppHandler(TestCase):
         self.assertIs(self.app.config, self.config)
         self.assertEqual(self.app.handlers, {})
 
+    def test_make_engine_from_config_basic(self):
+        engine = self.app.make_engine_from_config({
+            'sqlalchemy.url': 'sqlite://',
+        })
+        self.assertIsInstance(engine, Engine)
+
+    def test_make_engine_from_config_poolclass(self):
+
+        engine = self.app.make_engine_from_config({
+            'sqlalchemy.url': 'sqlite://',
+        })
+        self.assertNotIsInstance(engine.pool, NullPool)
+
+        engine = self.app.make_engine_from_config({
+            'sqlalchemy.url': 'sqlite://',
+            'sqlalchemy.poolclass': 'sqlalchemy.pool:NullPool',
+        })
+        self.assertIsInstance(engine.pool, NullPool)
+
+    def test_make_engine_from_config_pool_pre_ping(self):
+
+        engine = self.app.make_engine_from_config({
+            'sqlalchemy.url': 'sqlite://',
+        })
+        self.assertFalse(engine.pool._pre_ping)
+
+        engine = self.app.make_engine_from_config({
+            'sqlalchemy.url': 'sqlite://',
+            'sqlalchemy.pool_pre_ping': 'true',
+        })
+        self.assertTrue(engine.pool._pre_ping)
+
     def test_make_session(self):
         session = self.app.make_session()
         self.assertIsInstance(session, db.Session.class_)

tests/test_conf.py

@@ -117,6 +117,23 @@ baz = B
         self.assertIsNone(config.get('foo.bar'))
         self.assertEqual(config.get('foo.baz'), 'B')
 
+    def test_prioritized_files(self):
+        first = self.write_file('first.conf', """\
+[foo]
+bar = 1
+""")
+
+        second = self.write_file('second.conf', """\
+[wutta.config]
+require = %(here)s/first.conf
+""")
+
+        config = conf.WuttaConfig(files=[second])
+        files = config.get_prioritized_files()
+        self.assertEqual(len(files), 2)
+        self.assertEqual(files[0], second)
+        self.assertEqual(files[1], first)
+
     def test_constructor_defaults(self):
         config = conf.WuttaConfig()
         self.assertEqual(config.defaults, {})
@@ -351,6 +368,24 @@ configure_logging = true
         config = conf.WuttaConfig()
         self.assertRaises(ConfigurationError, config.require, 'foo')
 
+    def test_get_bool(self):
+        config = conf.WuttaConfig()
+        self.assertFalse(config.get_bool('foo.bar'))
+        config.setdefault('foo.bar', 'true')
+        self.assertTrue(config.get_bool('foo.bar'))
+
+    def test_get_int(self):
+        config = conf.WuttaConfig()
+        self.assertIsNone(config.get_int('foo.bar'))
+        config.setdefault('foo.bar', '42')
+        self.assertEqual(config.get_int('foo.bar'), 42)
+
+    def test_get_list(self):
+        config = conf.WuttaConfig()
+        self.assertEqual(config.get_list('foo.bar'), [])
+        config.setdefault('foo.bar', 'hello world')
+        self.assertEqual(config.get_list('foo.bar'), ['hello', 'world'])
+
 
 class TestGenericDefaultFiles(TestCase):
 

tests/test_util.py

@@ -190,6 +190,11 @@ class TestParseList(TestCase):
         self.assertIsInstance(value, list)
         self.assertEqual(len(value), 0)
 
+    def test_list_instance(self):
+        mylist = []
+        value = util.parse_list(mylist)
+        self.assertIs(value, mylist)
+
     def test_single_value(self):
         value = util.parse_list('foo')
         self.assertEqual(len(value), 1)