# Class yii\i18n\DbMessageSource

Inheritance | yii\i18n\DbMessageSource » yii\i18n\MessageSource » yii\base\Component » yii\base\BaseObject
Implements | yii\base\Configurable
Available since version | 2.0
Source Code | https://github.com/yiisoft/yii2/blob/master/framework/i18n/DbMessageSource.php

DbMessageSource extends yii\i18n\MessageSource and represents a message source that stores translated messages in database.

The database must contain the following two tables: source_message and message.

The `source_message` table stores the messages to be translated, and the `message` table stores the translated messages. The name of these two tables can be customized by setting $sourceMessageTable and $messageTable, respectively.

The database connection is specified by $db. Database schema could be initialized by applying migration:

    yii migrate --migrationPath=@yii/i18n/migrations/

If you don't want to use migration and need SQL instead, files for all databases are in migrations directory.

## Public Properties

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Property | Type | Description | Defined By
--- | --- | --- | ---
$behaviors | yii\base\Behavior[] | List of behaviors attached to this component. This property is read-only. | yii\base\Component
$cache | yii\caching\CacheInterface|array|string | The cache object or the application component ID of the cache object. | yii\i18n\DbMessageSource
$cachingDuration | integer | The time in seconds that the messages can remain valid in cache. | yii\i18n\DbMessageSource
$db | yii\db\Connection|array|string | The DB connection object or the application component ID of the DB connection. | yii\i18n\DbMessageSource
$enableCaching | boolean | Whether to enable caching translated messages | yii\i18n\DbMessageSource
$forceTranslation | boolean | Whether to force message translation when the source and target languages are the same. | yii\i18n\MessageSource
$messageTable | string | The name of the translated message table. | yii\i18n\DbMessageSource
$sourceLanguage | string | The language that the original messages are in. | yii\i18n\MessageSource
$sourceMessageTable | string | The name of the source message table. | yii\i18n\DbMessageSource

## Public Methods

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Method | Description | Defined By
--- | --- | ---
__call() | Calls the named method which is not a class method. | yii\base\Component
__clone() | This method is called after the object is created by cloning an existing one. | yii\base\Component
__construct() | Constructor. | yii\base\BaseObject
__get() | Returns the value of a component property. | yii\base\Component
__isset() | Checks if a property is set, i.e. defined and not null. | yii\base\Component
__set() | Sets the value of a component property. | yii\base\Component
__unset() | Sets a component property to be null. | yii\base\Component
attachBehavior() | Attaches a behavior to this component. | yii\base\Component
attachBehaviors() | Attaches a list of behaviors to the component. | yii\base\Component
behaviors() | Returns a list of behaviors that this component should behave as. | yii\base\Component
canGetProperty() | Returns a value indicating whether a property can be read. | yii\base\Component
canSetProperty() | Returns a value indicating whether a property can be set. | yii\base\Component
className() | Returns the fully qualified name of this class. | yii\base\BaseObject
detachBehavior() | Detaches a behavior from the component. | yii\base\Component
detachBehaviors() | Detaches all behaviors from the component. | yii\base\Component
ensureBehaviors() | Makes sure that the behaviors declared in behaviors() are attached to this component. | yii\base\Component
getBehavior() | Returns the named behavior object. | yii\base\Component
getBehaviors() | Returns all behaviors attached to this component. | yii\base\Component
hasEventHandlers() | Returns a value indicating whether there is any handler attached to the named event. | yii\base\Component
hasMethod() | Returns a value indicating whether a method is defined. | yii\base\Component
hasProperty() | Returns a value indicating whether a property is defined for this component. | yii\base\Component
init() | Initializes the DbMessageSource component. | yii\i18n\DbMessageSource
off() | Detaches an existing event handler from this component. | yii\base\Component
on() | Attaches an event handler to an event. | yii\base\Component
translate() | Translates a message to the specified language. | yii\i18n\MessageSource
trigger() | Triggers an event. | yii\base\Component

## Protected Methods

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Method | Description | Defined By
--- | --- | ---
createFallbackQuery() | The method builds the yii\db\Query object for the fallback language messages search. | yii\i18n\DbMessageSource
loadMessages() | Loads the message translation for the specified language and category. | yii\i18n\DbMessageSource
loadMessagesFromDb() | Loads the messages from database. | yii\i18n\DbMessageSource
translateMessage() | Translates the specified message. | yii\i18n\MessageSource

## Events

Hide inherited events

Event | Type | Description | Defined By
--- | --- | --- | ---
EVENT_MISSING_TRANSLATION | yii\i18n\MissingTranslationEvent | An event that is triggered when a message translation is not found. | yii\i18n\MessageSource

## Constants

Hide inherited constants

Constant | Value | Description | Defined By
--- | --- | --- | ---
CACHE_KEY_PREFIX | 'DbMessageSource' | Prefix which would be used when generating cache key. Deprecated This constant has never been used and will be removed in 2.1.0. | yii\i18n\DbMessageSource

## Property Details

$cache public property

The cache object or the application component ID of the cache object. The messages data will be cached using this cache object. Note, that to enable caching you have to set $enableCaching to `true`, otherwise setting this property has no effect.

After the DbMessageSource object is created, if you want to change this property, you should only assign it with a cache object.

Starting from version 2.0.2, this can also be a configuration array for creating the object.

See also:

- $cachingDuration
- $enableCaching

public yii\caching\CacheInterface|array|string $cache = 'cache'
$cachingDuration public property

The time in seconds that the messages can remain valid in cache. Use 0 to indicate that the cached data will never expire.

See also $enableCaching.

public integer $cachingDuration = 0
$db public property

The DB connection object or the application component ID of the DB connection.

After the DbMessageSource object is created, if you want to change this property, you should only assign it with a DB connection object.

Starting from version 2.0.2, this can also be a configuration array for creating the object.

public yii\db\Connection|array|string $db = 'db'
$enableCaching public property

Whether to enable caching translated messages

public boolean $enableCaching = false
$messageTable public property

The name of the translated message table.

public string $messageTable = '{{%message}}'
$sourceMessageTable public property

The name of the source message table.

public string $sourceMessageTable = '{{%source_message}}'

## Method Details

createFallbackQuery() protected method (available since version 2.0.7)

The method builds the yii\db\Query object for the fallback language messages search.

Normally is called from loadMessagesFromDb().

See also loadMessagesFromDb().

protected yii\db\Query createFallbackQuery ( $category, $language, $fallbackLanguage )
$category | string | The message category
$language | string | The originally requested language
$fallbackLanguage | string | The target fallback language

init() public method

Initializes the DbMessageSource component.

This method will initialize the $db property to make sure it refers to a valid DB connection. Configured $cache component would also be initialized.

public void init ( )
throws | yii\base\InvalidConfigException | if $db is invalid or $cache is invalid.

loadMessages() protected method

Loads the message translation for the specified language and category.

If translation for specific locale code such as `en-US` isn't found it tries more generic `en`.

protected array loadMessages ( $category, $language )
$category | string | The message category
$language | string | The target language
return | array | The loaded messages. The keys are original messages, and the values are translated messages.

loadMessagesFromDb() protected method

Loads the messages from database.

You may override this method to customize the message storage in the database.

protected array loadMessagesFromDb ( $category, $language )
$category | string | The message category.
$language | string | The target language.
return | array | The messages loaded from database.