Merge pull request #137 from tarsil/feat/new-settings

New settings core

saffier/cli/templates/default/env.py

@@ -131,7 +131,7 @@ def is_async_connection(url: DatabaseURL) -> bool:
         (url.driver in settings.postgres_drivers)
         or (url.driver in settings.mysql_drivers)
         or (url.driver in settings.sqlite_drivers)
-        or url.driver in settings.mssql_drivers
+        or url.driver in settings.mssql_drivers  # type: ignore
     ):
         return True
     return False

saffier/conf/__init__.py

@@ -1,10 +1,51 @@
 import os
+from typing import TYPE_CHECKING, Any, Optional, Type
 
-os.environ.setdefault("OVERRIDE_SETTINGS_MODULE_VARIABLE", "SAFFIER_SETTINGS_MODULE")
+from saffier.conf.functional import LazyObject, empty
+from saffier.conf.module_import import import_string
 
-if not os.environ.get("SAFFIER_SETTINGS_MODULE"):
-    os.environ.setdefault(
-        "SAFFIER_SETTINGS_MODULE", "saffier.conf.global_settings.SaffierSettings"
-    )
+if TYPE_CHECKING:
+    from saffier.conf.global_settings import SaffierSettings
 
-from dymmond_settings import settings as settings  # noqa
+ENVIRONMENT_VARIABLE = "SAFFIER_SETTINGS_MODULE"
+
+
+class SaffierLazySettings(LazyObject):
+    """
+    A lazy proxy for either global Saffier settings or a custom settings object.
+    The user can manually configure settings prior to using them. Otherwise,
+    Saffier uses the settings module pointed to by LILYA_SETTINGS_MODULE.
+    """
+
+    def _setup(self, name: Optional[str] = None) -> None:
+        """
+        Load the settings module pointed to by the environment variable. This
+        is used the first time settings are needed, if the user hasn't
+        configured settings manually.
+        """
+        settings_module: str = os.environ.get(
+            ENVIRONMENT_VARIABLE, "saffier.conf.global_settings.SaffierSettings"
+        )
+
+        settings: Type["SaffierSettings"] = import_string(settings_module)
+
+        for setting, _ in settings().dict().items():
+            assert setting.islower(), "%s should be in lowercase." % setting
+
+        self._wrapped = settings()
+
+    def __repr__(self: "SaffierLazySettings") -> str:
+        # Hardcode the class name as otherwise it yields 'SaffierSettings'.
+        if self._wrapped is empty:
+            return "<SaffierLazySettings [Unevaluated]>"
+        return '<SaffierLazySettings "{settings_module}">'.format(
+            settings_module=self._wrapped.__class__.__name__
+        )
+
+    @property
+    def configured(self) -> Any:
+        """Return True if the settings have already been configured."""
+        return self._wrapped is not empty
+
+
+settings: Type["SaffierSettings"] = SaffierLazySettings()  # type: ignore

saffier/core/connection/registry.py

@@ -55,7 +55,7 @@ def _get_database_url(self) -> str:
                 url = url.replace(driver="aiosqlite")
             elif url.dialect in settings.mssql_dialects:
                 raise ImproperlyConfigured("Saffier does not support MSSQL at the moment.")
-        elif url.driver in settings.mssql_drivers:
+        elif url.driver in settings.mssql_drivers:  # type: ignore
             raise ImproperlyConfigured("Saffier does not support MSSQL at the moment.")
         return str(url)