# Preferences

Preferences are user based configuration for Icinga 2 Web. For example max page
items, languages or date time settings can controlled by users.

# Architecture

Preferences are initially loaded from a provider (ini files or database) and
stored into session at login time. After this step preferences are only
persisted to the configured backend, but never reloaded from them.

# Configuration

Preferences can be configured in config.ini in **preferences** section, default
settings are this:

    [preferences]
    type=ini

The ini provider uses the directory **config/preferences** to create one ini
file per user and persists the data into a single file. If you want to drop your
preferences just drop the file from disk and you'll start with a new profile.

## Database Provider

To be more flexible in distributed setups you can store preferences in a
database (pgsql or mysql), a typical configuration looks like the following
example:

    [preferences]
    type=db
    resource=icingaweb-pgsql

## Null Provider

The Null Provider discards all preferences and is mainly used as a fallback when no provider could be
created (due to permission errors, database outtakes, etc.).

    [preferences]
    type=null

If your preferences aren't stored it's best to take a look into the logfiles - errors during the preference setup
are displayed as warnings here.

### Settings

* **resource**: A reference to a database declared in *resources.ini*. Please read the chapter about
 resources for a detailed description about how to set up resources.

### Preparation

To use this feature you need a running database environment. After creating a
database and a writable user you need to import the initial table file:

* etc/schema/preferences.mysql.sql (for mysql database)
* etc/schema/preferemces.pgsql.sql (for postgres databases)

#### Example for mysql

    # mysql -u root -p
    mysql> create database icingaweb;
    mysql> GRANT SELECT,INSERT,UPDATE,DELETE ON icingaweb.* TO \
        'icingaweb'@'localhost' IDENTIFIED BY 'icingaweb';
    mysql> exit
    # mysql -u root -p icingaweb < /path/to/icingaweb/etc/schema/preferences.mysql.sql

After following these steps above you can configure your preferences provider.

## Coding API

You can set, update or remove preferences using the Preference data object
which is bound to the user. Here are some simple examples how to work with
that:

    $preferences = $user->getPreferences();
    // Get language with en_US as fallback
    $preferences->get('app.language', 'en_US');
    $preferences->set('app.language', 'de_DE');
    $preferences->remove('app.language');

    // Using transactional mode
    $preferences->startTransaction();
    $preferences->set('test.pref1', 'pref1');
    $preferences->set('test.pref2', 'pref2');
    $preferences->remove('test.pref3');
    $preferemces->commit(); // Stores 3 changes in one operation

More information can be found in the api docs.

## Namespaces and behaviour

If you are using this API please obey the following rules:

* Use dotted notation for preferences
* Namespaces starting with one context identifier
    * **app** as global identified (e.g. app.language)
    * **mymodule** for your module
    * **monitoring** for the monitoring module
* Use preferences wisely (set only when needed and write small settings)
* Use only simple data types, e.g. strings or numbers
    * If you need complex types you have to do it your self (e.g. serialization)