Complete processing pipeline for Signal

core/util/django_settings_export.py

@@ -0,0 +1,69 @@
+"""
+Export Django settings to templates
+
+https://github.com/jakubroztocil/django-settings-export
+
+"""
+from django.conf import settings as django_settings
+from django.core.exceptions import ImproperlyConfigured
+
+__version__ = "1.2.1"
+
+
+VARIABLE_NAME = getattr(django_settings, "SETTINGS_EXPORT_VARIABLE_NAME", "settings")
+
+
+class SettingsExportError(ImproperlyConfigured):
+    """Base error indicating misconfiguration."""
+
+
+class UndefinedSettingError(SettingsExportError):
+    """An undefined setting name included in SETTINGS_EXPORT."""
+
+
+class UnexportedSettingError(SettingsExportError):
+    """An unexported setting has been accessed from a template."""
+
+
+def settings_export(request):
+    """
+    The template context processor that adds settings defined in
+    `SETTINGS_EXPORT` to the context. If SETTINGS_EXPORT_VARIABLE_NAME is not
+    set, the context variable will be `settings`.
+
+    """
+    variable_name = getattr(
+        django_settings, "SETTINGS_EXPORT_VARIABLE_NAME", "settings"
+    )
+    return {variable_name: _get_exported_settings()}
+
+
+class ExportedSettings(dict):
+    def __getitem__(self, item):
+        """Fail loudly if accessing a setting that is not exported."""
+        try:
+            return super(ExportedSettings, self).__getitem__(item)
+        except KeyError:
+            if hasattr(self, item):
+                # Let the KeyError propagate so that Django templates
+                # can access the existing attribute (e.g. `items()`).
+                raise
+            raise UnexportedSettingError(
+                "The `{key}` setting key is not accessible"
+                ' from templates: add "{key}" to'
+                " `settings.SETTINGS_EXPORT` to change that.".format(key=item)
+            )
+
+
+def _get_exported_settings():
+    exported_settings = ExportedSettings()
+    for key in getattr(django_settings, "SETTINGS_EXPORT", []):
+        try:
+            value = getattr(django_settings, key)
+        except AttributeError:
+            raise UndefinedSettingError(
+                '"settings.%s" is included in settings.SETTINGS_EXPORT '
+                "but it does not exist. " % key
+            )
+        exported_settings[key] = value
+    return exported_settings