Is the MODULE.schema.yml required when you define the MODULE.settings.yml?

Question

Is the MODULE.schema.yml required when you define the MODULE.settings.yml? It seems that it also works when I remove the MODULE.schema.yml file from install/schema.

Answer 1

It is not absolutely required but strongly recommended to have one.

By default, Drupal doesn't validate the schema, but it does in tests and there is an issue that will enable it if you use the provided example.settings.local.php/development.services.yml. That's why you don't see an error right now when you install, but you'll see it when you write your first test.

It is currently used to ensure the saved configuration has the right data type (e.g. a float and not an integer); not doing that correctly can break stuff and the ability of translating the configuration. More things might follow later, for example a module that generates a settings form.

Answer 2

The settings.yml is only needed when you want to have default values to start with in your config after the module is installed.

Answer 3

MODULE/config/install/MODULE.settings.yml file is not mandatory.

MODULE.settings.yml file is basically used for configure default values. and that will only affect when you install module first time.

Two options available for reflect changes in MODULE.settings.yml:

1. Uninstall MODULE and Install it again!
2. Use MODULE.install file and hook_update_N(&$sandbox)

e.g. Filename: MODULE/MODULE.install

    /**
     * Write a line or two here about what the updates are for.
     * This is shown to users on the update.php page.
     */
    function mymodule_update_8001(&$sandbox) {
      $config_factory = \Drupal::configFactory();
      $default_value = 'Test';
      $config_factory->getEditable('MODULE.settings')->set('config_field_key', $default_value)->save();
    }

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