Config Lexicon

Signed-off-by: Maxence Lange <maxence@artificial-owl.com>

developer_manual/digging_deeper/config/appconfig.rst

@@ -40,6 +40,14 @@ On top of storing and accessing your configuration values, ``IAppConfig`` comes
 
 .. _appconfig_concepts:
 
+
+.. note::
+	See `Lexicon Concepts`_ to learn more about **Lexicon**, a way to fully define your configuration keys and avoid conflict when using it in your code.
+
+.. _Lexicon Concepts: https://docs.nextcloud.com/server/latest/developer_manual/digging_deeper/config/lexicon.html#concept-overview
+
+
+
 Typed Config Values
 ^^^^^^^^^^^^^^^^^^^
 

developer_manual/digging_deeper/config/index.rst

@@ -7,3 +7,4 @@ Config & Preferences
 
    appconfig
    userconfig
+   lexicon

developer_manual/digging_deeper/config/lexicon.rst

@@ -0,0 +1,151 @@
+=======
+Lexicon
+=======
+
+.. versionadded:: 32
+
+Since v32, Nextcloud provides a way to centralize the definition of your app's configuration keys and values in a single place.
+
+
+Concept overview
+----------------
+
+Nextcloud includes the ``ILexicon`` API to create a **Lexicon** of your config keys.
+This lexicon allow developers to define the config keys of their apps, their value type and additional details.
+
+.. _lexicon_concepts:
+
+Enforcing a unique configuration for each of your config keys in a single location help avoid their misuse.
+
+Details about each config key are:
+    - config value expected type,
+    - a default value,
+    - a description of its use,
+    - lazy loading setting,
+    - flags the config key as sensitive or indexable
+
+
+Registering your Lexicon
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+The Lexicon is set in a local class that implements `\OCP\Config\Lexicon\ILexicon` and registered from your ``Application.php``:
+
+.. code-block:: php
+
+	public function register(IRegistrationContext $context): void {
+		$context->registerConfigLexicon(\OCA\MyApp\ConfigLexicon::class);
+	}
+
+Example of the registered ``ConfigLexicon.php``:
+
+.. code-block:: php
+
+	use OCP\Config\Lexicon\Entry;
+	use OCP\Config\Lexicon\ILexicon;
+	use OCP\Config\Lexicon\Strictness;
+	use OCP\Config\ValueType;
+
+	class Lexicon implements ILexicon {
+		public function getStrictness(): Strictness {
+			return Strictness::WARNING;
+		}
+
+		public function getAppConfigs(): array {
+			return [
+				new Entry('key1', ValueType::STRING, 'abcde', 'test key', true, IAppConfig::FLAG_SENSITIVE),
+				new Entry('key2', ValueType::INT, 12345, 'test key', false)
+			];
+		}
+
+		public function getUserConfigs(): array {
+			return [
+				new Entry('key1', ValueType::STRING, 'abcde', 'test key', true, IUserConfig::FLAG_SENSITIVE),
+				new Entry('key2', ValueType::INT, 12345, 'test key', false)
+			];
+		}
+	}
+
+
+Each method ``getUserConfigs()`` and ``getAppConfigs()`` returns a list of ``\OCP\Config\Lexicon\Entry``.
+
+``getStrictness()`` is used to define the expected behavior of the process when reaching a config keys that is not listed in your app's Config Lexicon.
+Must returns a value from enum ``\OCP\Config\Lexicon\Strictness``.
+
+Available values:
+ * ``::IGNORE`` - does not limit the set/get on an unknown config key.
+ * ``::NOTICE`` - does not limit the set/get on an unknown config key, but generate a notice in the logs.
+ * ``::WARNING`` - unknown config key will not be set, and get will returns the default value. A warning will be issued in the logs.
+ * ``::EXCEPTION`` - set/get on an unknown config key will generate an exception.
+
+
+Config Lexicon Entry
+^^^^^^^^^^^^^^^^^^^^
+
+Each config key is defined in a object through those arguments:
+
+.. code-block:: php
+
+	new Entry(
+		key: 'my_config_key',        // config key
+		type: ValueType::STRING,     // expected value type when the code set/get value
+		defaultRaw: 'default value', // value to returns if a config value is not available in the database
+		definition: 'this is a description of the use for this config key',
+		lazy: true,                  // config value is stored as lazy
+		flags: FLAG_SENSITIVE,       // value is sensitive and/or indexable, using IAppConfig::FLAG_*, IUserConfig::FLAG_*
+		deprecated: false,           // if set to ``true`` will generate a notice entry in the nextcloud logs when called
+	);
+
+.. note:: Unless if set to ``null``, the default value set in the config lexicon overwrite the default value used as argument when calling ``getValueString('my_config_key', 'another default value');``
+
+Preset
+^^^^^^
+
+With 32, Nextcloud comes with a list of `preset` to ease the default user experience, based on the context of the instance.
+The selection of a preset is optional and can be done right after the setup of Nextcloud, and any time in the future using this occ command:
+
+.. code-block:: bash
+
+	$ ./occ config:preset
+	current preset: NONE
+	$ ./occ config:preset PRIVATE
+	current preset: PRIVATE
+
+If you want your app to have a different default value based on the selected Preset, you need to generate a Closure as ``$defaultRaw`` when generating the Lexicon Entry.
+The first parameter of the Closure is an Enum ``'\OCP\Config\Lexicon\Preset'`` that define the current Preset:
+
+.. code-block:: php
+
+	new Entry('key3', ValueType::STRING, fn (Preset $p): string => match ($p) {
+				Preset::FAMILY => 'family',
+				Preset::CLUB, Preset::MEDIUM => 'club+medium',
+				default => 'none',
+			}),
+
+Available values:
+ * ``::LARGE`` - Large size organisation (> 50k accounts)
+ * ``::MEDIUM`` - Medium size organisation (> 100 accounts)
+ * ``::SMALL`` - Small size organisation (< 100 accounts)
+ * ``::SHARED`` - Shared hosting
+ * ``::EDUCATION`` - School/University
+ * ``::CLUB`` - Club/Association
+ * ``::FAMILY`` - Family
+ * ``::PRIVATE`` - Private
+
+
+
+./occ config:app:get --details
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Details from the Lexicon can be extracted using the ``occ`` command
+
+.. code-block:: bash
+
+	$ ./occ config:app:get myapp my_config_key --details
+	  - app: myapp
+	  - key: my_config_key
+	  - value: 'a_value'
+	  - type: string
+	  - lazy: true
+      - description:
+	  - sensitive: false
+

developer_manual/digging_deeper/config/userconfig.rst

@@ -15,6 +15,12 @@ On top of storing and accessing your configuration values, ``IUserConfig`` comes
 
 .. _userconfig_concepts:
 
+.. note::
+	See `Lexicon Concepts`_ to learn more about **Lexicon**, a way to fully define your configuration keys and avoid conflict when using it in your code.
+
+.. _Lexicon Concepts: https://docs.nextcloud.com/server/latest/developer_manual/digging_deeper/config/lexicon.html#concept-overview
+
+
 Typed Config Values
 ^^^^^^^^^^^^^^^^^^^