# orion.core.setting

Orion plugins can define settings using the `orion.core.setting` service. A setting defines some persistent information that is provided to one of the plugin's services. Defined settings appear on Orion's Settings page, and their values can be changed using an automatically-generated UI.

A setting is a combination of two more basic configuration elements:

- A ''PID'' (persistent identifier), which uniquely identifies the configuration data for the setting.
- ''Metatype'' information, which defines the "shape" of the setting. Specifically, it defines what named properties appear in the setting and what data type they have (string, boolean, number, etc). The Settings page uses this Metatype information to generate appropriate UI widgets (for example, text field, checkbox, etc).

## Service properties

To contribute one or more settings, the settings service property is used:

settings
  `Setting[]`. Defines Settings. Each `Setting` element has the following shape:
  pid
    `String`. The PID for this setting. This PID occupies the same namespace as the PIDs contributed by Managed Services, and must be unique in that respect.
  name
    `String`. Human-readable name of this setting.
  tags
    `String[]`. Optional. List of tags applying to this setting.
  properties
    `AttributeDefinition[]`. Gives the properties that make up this setting. The shape of the `AttributeDefinition` element is explained in Metatype documentation.

## Service methods

None. This service is completely declarative.

## Examples

This example shows how to define a Setting with PID `example.navconfig`. This Setting has a single property `newtab`, which is boolean-typed. Because we've enumerated the property's possible values using an options, the generated UI presentation will show a drop-down menu. Since we've provided a defaultValue of `false`, the second option "Open links in a same tab" will selected by default.

    define('orion/plugin', function(PluginProvider) {
        var pluginProvider = new PluginProvider();
        pluginProvider.registerService('orion.core.setting',
            {},
            {  settings: [
                   {  pid: 'example.navconfig',
                      name: 'Navigation settings',
                      properties: [
                          {  id: 'newtab',
                             name: 'Links',
                             type: 'boolean',
                             defaultValue: false,
                             options: [
                                 {  label: "Open links in a new tab",
                                    value: true
                                 },
                                 {  label: "Open links in same tab",
                                    value: false
                                 }
                             ]
                          }
                      ]
                   }
               ]
            });
        provider.connect();
    });

When a user visits the Orion Settings page, they'll see an automatically-generated UI containing a drop-down menu, similar to the one shown below. Manipulating the drop-down menu causes the setting's value to change, and causes any Managed Services registered against the `example.navconfig` PID to have their [[Orion/Documentation/Developer Guide/Configuration services#Service methods|`updated()` methods]] invoked.

## See also

- Configuration services