Gio.Settings
Description: Reference for Gio.Settings

### Class

# GioSettings

#### Description [src]

    class Gio.Settings : GObject.Object
    {
      priv: GSettingsPrivate*
    }

The `GSettings` class provides a convenient API for storing and retrieving application settings.

Reads and writes can be considered to be non-blocking. Reading settings with `GSettings` is typically extremely fast: on approximately the same order of magnitude (but slower than) a `GHashTable` lookup. Writing settings is also extremely fast in terms of time to return to your application, but can be extremely expensive for other threads and other processes. Many settings backends (including dconf) have lazy initialisation which means in the common case of the user using their computer without modifying any settings a lot of work can be avoided. For dconf, the D-Bus service doesn’t even need to be started in this case. For this reason, you should only ever modify `GSettings` keys in response to explicit user action. Particular care should be paid to ensure that modifications are not made during startup — for example, when setting the initial value of preferences widgets. The built-in `g_settings_bind()` functionality is careful not to write settings in response to notify signals as a result of modifications that it makes to widgets.

When creating a `GSettings` instance, you have to specify a schema that describes the keys in your settings and their types and default values, as well as some other information.

Normally, a schema has a fixed path that determines where the settings are stored in the conceptual global tree of settings. However, schemas can also be ‘relocatable’, i.e. not equipped with a fixed path. This is useful e.g. when the schema describes an ‘account’, and you want to be able to store a arbitrary number of accounts.

Paths must start with and end with a forward slash character (`/`) and must not contain two sequential slash characters. Paths should be chosen based on a domain name associated with the program or library to which the settings belong. Examples of paths are `/org/gtk/settings/file-chooser/` and `/ca/desrt/dconf-editor/`. Paths should not start with `/apps/`, `/desktop/` or `/system/` as they often did in GConf.

Unlike other configuration systems (like GConf), GSettings does not restrict keys to basic types like strings and numbers. GSettings stores values as `GVariant`, and allows any `GVariantType` for keys. Key names are restricted to lowercase characters, numbers and `-`. Furthermore, the names must begin with a lowercase character, must not end with a `-`, and must not contain consecutive dashes.

Similar to GConf, the default values in GSettings schemas can be localized, but the localized values are stored in gettext catalogs and looked up with the domain that is specified in the `gettext-domain` attribute of the `<schemalist>` or `<schema>` elements and the category that is specified in the `l10n` attribute of the `<default>` element. The string which is translated includes all text in the `<default>` element, including any surrounding quotation marks.

The `l10n` attribute must be set to `messages` or `time`, and sets the locale category for translation. The `messages` category should be used by default; use `time` for translatable date or time formats. A translation comment can be added as an XML comment immediately above the `<default>` element — it is recommended to add these comments to aid translators understand the meaning and implications of the default value. An optional translation `context` attribute can be set on the `<default>` element to disambiguate multiple defaults which use the same string.

For example:

     <!-- Translators: A list of words which are not allowed to be typed, in
          GVariant serialization syntax.
          See: https://developer.gnome.org/glib/stable/gvariant-text.html -->
     <default l10n='messages' context='Banned words'>['bad', 'words']</default>

Translations of default values must remain syntactically valid serialized `GVariant`s (e.g. retaining any surrounding quotation marks) or runtime errors will occur.

GSettings uses schemas in a compact binary form that is created by the `glib-compile-schemas` utility. The input is a schema description in an XML format.

A DTD for the gschema XML format can be found here: gschema.dtd

The `glib-compile-schemas` tool expects schema files to have the extension `.gschema.xml`.

At runtime, schemas are identified by their ID (as specified in the `id` attribute of the `<schema>` element). The convention for schema IDs is to use a dotted name, similar in style to a D-Bus bus name, e.g. `org.gnome.SessionManager`. In particular, if the settings are for a specific service that owns a D-Bus bus name, the D-Bus bus name and schema ID should match. For schemas which deal with settings not associated with one named application, the ID should not use StudlyCaps, e.g. `org.gnome.font-rendering`.

In addition to `GVariant` types, keys can have types that have enumerated types. These can be described by a `<choice>`, `<enum>` or `<flags>` element, as seen in the second example below. The underlying type of such a key is string, but you can use `g_settings_get_enum()`, `g_settings_set_enum()`, `g_settings_get_flags()`, `g_settings_set_flags()` access the numeric values corresponding to the string value of enum and flags keys.

An example for default value:

    <schemalist>
      <schema id="org.gtk.Test" path="/org/gtk/Test/" gettext-domain="test">

        <key name="greeting" type="s">
          <default l10n="messages">"Hello, earthlings"</default>
          <summary>A greeting</summary>
          <description>
            Greeting of the invading martians
          </description>
        </key>

        <key name="box" type="(ii)">
          <default>(20,30)</default>
        </key>

        <key name="empty-string" type="s">
          <default>""</default>
          <summary>Empty strings have to be provided in GVariant form</summary>
        </key>

      </schema>
    </schemalist>

An example for ranges, choices and enumerated types:

    <schemalist>

      <enum id="org.gtk.Test.myenum">
        <value nick="first" value="1"/>
        <value nick="second" value="2"/>
      </enum>

      <flags id="org.gtk.Test.myflags">
        <value nick="flag1" value="1"/>
        <value nick="flag2" value="2"/>
        <value nick="flag3" value="4"/>
      </flags>

      <schema id="org.gtk.Test">

        <key name="key-with-range" type="i">
          <range min="1" max="100"/>
          <default>10</default>
        </key>

        <key name="key-with-choices" type="s">
          <choices>
            <choice value='Elisabeth'/>
            <choice value='Annabeth'/>
            <choice value='Joe'/>
          </choices>
          <aliases>
            <alias value='Anna' target='Annabeth'/>
            <alias value='Beth' target='Elisabeth'/>
          </aliases>
          <default>'Joe'</default>
        </key>

        <key name='enumerated-key' enum='org.gtk.Test.myenum'>
          <default>'first'</default>
        </key>

        <key name='flags-key' flags='org.gtk.Test.myflags'>
          <default>["flag1","flag2"]</default>
        </key>
      </schema>
    </schemalist>

## Vendor overrides

Default values are defined in the schemas that get installed by an application. Sometimes, it is necessary for a vendor or distributor to adjust these defaults. Since patching the XML source for the schema is inconvenient and error-prone, `glib-compile-schemas` reads so-called ‘vendor override’ files. These are keyfiles in the same directory as the XML schema sources which can override default values. The schema ID serves as the group name in the key file, and the values are expected in serialized `GVariant` form, as in the following example:

    [org.gtk.Example]
    key1='string'
    key2=1.5

`glib-compile-schemas` expects schema files to have the extension `.gschema.override`.

## Delay-apply mode

By default, values set on a `GSettings` instance immediately start to be written to the backend (although these writes may not complete by the time that `g_settings_set()`) returns; see `g_settings_sync()`).

In order to allow groups of settings to be changed simultaneously and atomically, GSettings also supports a ‘delay-apply’ mode. In this mode, updated values are kept locally in the `GSettings` instance until they are explicitly applied by calling `g_settings_apply()`.

For example, this could be useful for a preferences dialog where the preferences all need to be applied simultaneously when the user clicks ‘Save’.

Switching a `GSettings` instance to ‘delay-apply’ mode is a one-time irreversible operation: from that point onwards, all changes made to that `GSettings` have to be explicitly applied by calling `g_settings_apply()`. The ‘delay-apply’ mode is also propagated to any child settings objects subsequently created using `g_settings_get_child()`.

At any point, the set of unapplied changes can be queried using `GSettings:has-unapplied`, and discarded by calling `g_settings_revert()`.

## Binding

A very convenient feature of GSettings lets you bind `GObject` properties directly to settings, using `g_settings_bind()`. Once a `GObject` property has been bound to a setting, changes on either side are automatically propagated to the other side. GSettings handles details like mapping between `GObject` and `GVariant` types, and preventing infinite cycles.

This makes it very easy to hook up a preferences dialog to the underlying settings. To make this even more convenient, GSettings looks for a boolean property with the name `sensitivity` and automatically binds it to the writability of the bound setting. If this ‘magic’ gets in the way, it can be suppressed with the `G_SETTINGS_BIND_NO_SENSITIVITY` flag.

## Relocatable schemas

A relocatable schema is one with no `path` attribute specified on its `<schema>` element. By using `g_settings_new_with_path()`, a `GSettings` object can be instantiated for a relocatable schema, assigning a path to the instance. Paths passed to `g_settings_new_with_path()` will typically be constructed dynamically from a constant prefix plus some form of instance identifier; but they must still be valid GSettings paths. Paths could also be constant and used with a globally installed schema originating from a dependency library.

For example, a relocatable schema could be used to store geometry information for different windows in an application. If the schema ID was `org.foo.MyApp.Window`, it could be instantiated for paths `/org/foo/MyApp/main/`, `/org/foo/MyApp/document-1/`, `/org/foo/MyApp/document-2/`, etc. If any of the paths are well-known they can be specified as `<child>` elements in the parent schema, e.g.:

    <schema id="org.foo.MyApp" path="/org/foo/MyApp/">
      <child name="main" schema="org.foo.MyApp.Window"/>
    </schema>

## Build system integration

### Meson

GSettings is natively supported by Meson’s GNOME module.

You can install the schemas as any other data file:

    install_data(
      'org.foo.MyApp.gschema.xml',
      install_dir: get_option('datadir') / 'glib-2.0/schemas',
    )

You can use `gnome.post_install()` function to compile the schemas on installation:

    gnome = import('gnome')
    gnome.post_install(
      glib_compile_schemas: true,
    )

If an enumerated type defined in a C header file is to be used in a GSettings schema, it can either be defined manually using an `<enum>` element in the schema XML, or it can be extracted automatically from the C header. This approach is preferred, as it ensures the two representations are always synchronised. To do so, you will need to use the `gnome.mkenums()` function with the following templates:

    schemas_enums = gnome.mkenums('org.foo.MyApp.enums.xml',
      comments: '<!-- @comment@ -->',
      fhead: '<schemalist>',
      vhead: '  <@type@ id="org.foo.MyApp.@EnumName@">',
      vprod: '    <value nick="@valuenick@" value="@valuenum@"/>',
      vtail: '  </@type@>',
      ftail: '</schemalist>',
      sources: enum_sources,
      install_header: true,
      install_dir: get_option('datadir') / 'glib-2.0/schemas',
    )

It is recommended to validate your schemas as part of the test suite for your application:

    test('validate-schema',
      find_program('glib-compile-schemas'),
      args: ['--strict', '--dry-run', meson.current_source_dir()],
    )

If your application allows running uninstalled, you should also use the `gnome.compile_schemas()` function to compile the schemas in the current build directory:

    gnome.compile_schemas()

### Autotools

GSettings comes with autotools integration to simplify compiling and installing schemas. To add GSettings support to an application, add the following to your `configure.ac`:

    GLIB_GSETTINGS

In the appropriate `Makefile.am`, use the following snippet to compile and install the named schema:

    gsettings_SCHEMAS = org.foo.MyApp.gschema.xml
    EXTRA_DIST = $(gsettings_SCHEMAS)

    @GSETTINGS_RULES@

If an enumerated type defined in a C header file is to be used in a GSettings schema, it can either be defined manually using an `<enum>` element in the schema XML, or it can be extracted automatically from the C header. This approach is preferred, as it ensures the two representations are always synchronised. To do so, add the following to the relevant `Makefile.am`:

    gsettings_ENUM_NAMESPACE = org.foo.MyApp
    gsettings_ENUM_FILES = my-app-enums.h my-app-misc.h

`gsettings_ENUM_NAMESPACE` specifies the schema namespace for the enum files, which are specified in `gsettings_ENUM_FILES`. This will generate a `org.foo.MyApp.enums.xml` file containing the extracted enums, which will be automatically included in the schema compilation, install and uninstall rules. It should not be committed to version control or included in `EXTRA_DIST`.

## Localization

No changes are needed to the build system to mark a schema XML file for translation. Assuming it sets the `gettext-domain` attribute, a schema may be marked for translation by adding it to `POTFILES.in`, assuming gettext 0.19 or newer is in use (the preferred method for translation):

    data/org.foo.MyApp.gschema.xml

Alternatively, if intltool 0.50.1 is in use:

    [type: gettext/gsettings]data/org.foo.MyApp.gschema.xml

GSettings will use gettext to look up translations for the `<summary>` and `<description>` elements, and also any `<default>` elements which have a `l10n` attribute set.

Translations must not be included in the `.gschema.xml` file by the build system, for example by using a rule to generate the XML file from a template.

#### Ancestors

- GObject

#### Constructors

###### g_settings_new

Creates a new `GSettings` object with the schema specified by `schema_id`.

since: 2.26

###### g_settings_new_full

Creates a new `GSettings` object with a given schema, backend and path.

since: 2.32

###### g_settings_new_with_backend

Creates a new `GSettings` object with the schema specified by `schema_id` and a given `GSettingsBackend`.

since: 2.26

###### g_settings_new_with_backend_and_path

Creates a new `GSettings` object with the schema specified by `schema_id` and a given `GSettingsBackend` and path.

since: 2.26

###### g_settings_new_with_path

Creates a new `GSettings` object with the relocatable schema specified by `schema_id` and a given path.

since: 2.26

#### Functions

###### g_settings_list_relocatable_schemas

Deprecated.

deprecated: 2.40 since: 2.28

###### g_settings_list_schemas

Deprecated.

deprecated: 2.40 since: 2.26

###### g_settings_sync

Ensures that all pending operations are complete for the default backend.

###### g_settings_unbind

Removes an existing binding for `property` on `object`.

since: 2.26

#### Instance methods

###### g_settings_apply

Applies any changes that have been made to the settings.

###### g_settings_bind

Create a binding between the `key` in the `settings` object and the property `property` of `object`.

since: 2.26

###### g_settings_bind_with_mapping

Create a binding between the `key` in the `settings` object and the property `property` of `object`.

since: 2.26

###### g_settings_bind_with_mapping_closures

Version of `g_settings_bind_with_mapping()` using closures instead of callbacks for easier binding in other languages.

since: 2.82

###### g_settings_bind_writable

Create a binding between the writability of `key` in the `settings` object and the property `property` of `object`.

since: 2.26

###### g_settings_create_action

Creates a `GAction` corresponding to a given `GSettings` key.

since: 2.32

###### g_settings_delay

Changes the `GSettings` object into ‘delay-apply’ mode.

since: 2.26

###### g_settings_get

Gets the value that is stored at `key` in `settings`.

since: 2.26

###### g_settings_get_boolean

Gets the value that is stored at `key` in `settings`.

since: 2.26

###### g_settings_get_child

Creates a child settings object which has a base path of `base-path/name`, where `base-path` is the base path of `settings` and `name` is as specified by the caller.

since: 2.26

###### g_settings_get_default_value

Gets the ‘default value’ of a key.

since: 2.40

###### g_settings_get_double

Gets the value that is stored at `key` in `settings`.

since: 2.26

###### g_settings_get_enum

Gets the value that is stored in `settings` for `key` and converts it to the enum value that it represents.

since: 2.26

###### g_settings_get_flags

Gets the value that is stored in `settings` for `key` and converts it to the flags value that it represents.

since: 2.26

###### g_settings_get_has_unapplied

Returns whether the `GSettings` object has any unapplied changes.

since: 2.26

###### g_settings_get_int

Gets the value that is stored at `key` in `settings`.

since: 2.26

###### g_settings_get_int64

Gets the value that is stored at `key` in `settings`.

since: 2.50

###### g_settings_get_mapped

Gets the value that is stored at `key` in `settings`, subject to application-level validation/mapping.

###### g_settings_get_range

Queries the range of a key.

deprecated: 2.40 since: 2.28

###### g_settings_get_string

Gets the value that is stored at `key` in `settings`.

since: 2.26

###### g_settings_get_strv

A convenience variant of `g_settings_get()` for string arrays.

since: 2.26

###### g_settings_get_uint

Gets the value that is stored at `key` in `settings`.

since: 2.30

###### g_settings_get_uint64

Gets the value that is stored at `key` in `settings`.

since: 2.50

###### g_settings_get_user_value

Checks the ‘user value’ of a key, if there is one.

since: 2.40

###### g_settings_get_value

Gets the value that is stored in `settings` for `key`.

since: 2.26

###### g_settings_is_writable

Finds out if a key can be written.

since: 2.26

###### g_settings_list_children

Gets the list of children on `settings`.

###### g_settings_list_keys

Introspects the list of keys on `settings`.

deprecated: 2.46

###### g_settings_range_check

Checks if the given `value` is of the correct type and within the permitted range for `key`.

deprecated: 2.40 since: 2.28

###### g_settings_reset

Resets `key` to its default value.

###### g_settings_revert

Reverts all unapplied changes to the settings.

###### g_settings_set

Sets `key` in `settings` to `value`.

since: 2.26

###### g_settings_set_boolean

Sets `key` in `settings` to `value`.

since: 2.26

###### g_settings_set_double

Sets `key` in `settings` to `value`.

since: 2.26

###### g_settings_set_enum

Looks up the enumerated type nick for `value` and writes it to `key`, within `settings`.

###### g_settings_set_flags

Looks up the flags type nicks for the bits specified by `value`, puts them in an array of strings and writes the array to `key`, within `settings`.

###### g_settings_set_int

Sets `key` in `settings` to `value`.

since: 2.26

###### g_settings_set_int64

Sets `key` in `settings` to `value`.

since: 2.50

###### g_settings_set_string

Sets `key` in `settings` to `value`.

since: 2.26

###### g_settings_set_strv

Sets `key` in `settings` to `value`.

since: 2.26

###### g_settings_set_uint

Sets `key` in `settings` to `value`.

since: 2.30

###### g_settings_set_uint64

Sets `key` in `settings` to `value`.

since: 2.50

###### g_settings_set_value

Sets `key` in `settings` to `value`.

since: 2.26

##### Methods inherited from GObject (43)

Please see GObject for a full list of methods.

#### Properties

###### Gio.Settings:backend

The name of the context that the settings are stored in.

###### Gio.Settings:delay-apply

Whether the `GSettings` object is in ‘delay-apply’ mode.

since: 2.28

###### Gio.Settings:has-unapplied

Whether the `GSettings` object has outstanding changes.

###### Gio.Settings:path

The path within the backend where the settings are stored.

###### Gio.Settings:schema

The name of the schema that describes the types of keys for this `GSettings` object.

deprecated: 2.32

###### Gio.Settings:schema-id

The name of the schema that describes the types of keys for this `GSettings` object.

###### Gio.Settings:settings-schema

The `GSettingsSchema` describing the types of keys for this `GSettings` object.

#### Signals

###### Gio.Settings::change-event

Emitted once per change event that affects this settings object.

###### Gio.Settings::changed

Emitted when a key has potentially changed.

###### Gio.Settings::writable-change-event

Emitted once per writability change event that affects this settings object.

###### Gio.Settings::writable-changed

Emitted when the writability of a key has potentially changed.

##### Signals inherited from GObject (1)

###### GObject::notify

The notify signal is emitted on an object when one of its properties has its value set through g_object_set_property(), g_object_set(), et al.

#### Class structure

    struct GioSettingsClass {
      GObjectClass parent_class;
      void (* writable_changed) (
        GSettings* settings,
        const gchar* key
      );
      void (* changed) (
        GSettings* settings,
        const gchar* key
      );
      gboolean (* writable_change_event) (
        GSettings* settings,
        GQuark key
      );
      gboolean (* change_event) (
        GSettings* settings,
        const GQuark* keys,
        gint n_keys
      );
      None padding;

    }

No description available.

###### Class members

`parent_class: GObjectClass`

  No description available.

`writable_changed: void (* writable_changed) ( GSettings* settings, const gchar* key )`

  No description available.

`changed: void (* changed) ( GSettings* settings, const gchar* key )`

  No description available.

`writable_change_event: gboolean (* writable_change_event) ( GSettings* settings, GQuark key )`

  No description available.

`change_event: gboolean (* change_event) ( GSettings* settings, const GQuark* keys, gint n_keys )`

  No description available.

`padding: None`

  No description available.

#### Virtual methods

###### Gio.SettingsClass.change_event

No description available.

###### Gio.SettingsClass.changed

No description available.

###### Gio.SettingsClass.writable_change_event

No description available.

###### Gio.SettingsClass.writable_changed

No description available.