Container

API reference › yii › di › Container

class	yii\di\Container
Extends	yii\base\Component » yii\base\BaseObject
Implements	yii\base\Configurable
Since	2.0
Source	framework/di/Container.php

Container implements a dependency injection container.

A dependency injection (DI) container is an object that knows how to instantiate and configure objects and all their dependent objects. For more information about DI, please refer to Martin Fowler’s article.

Container supports constructor injection as well as property injection.

To use Container, you first need to set up the class dependencies by calling set(). You then call get() to create a new class object. The Container will automatically instantiate dependent objects, inject them into the object being created, configure, and finally return the newly created object.

By default, Yii::$container refers to a Container instance which is used by Yii::createObject() to create new object instances. You may use this method to replace the new operator when creating a new object, which gives you the benefit of automatic dependency resolution and default property configuration.

Below is an example of using Container:

namespace app\models;

use yii\base\BaseObject;
use yii\db\Connection;
use yii\di\Container;

interface UserFinderInterface
{
    function findUser();
}

class UserFinder extends BaseObject implements UserFinderInterface
{
    public $db;

    public function __construct(Connection $db, $config = [])
    {
        $this->db = $db;
        parent::__construct($config);
    }

    public function findUser()
    {
    }
}

class UserLister extends BaseObject
{
    public $finder;

    public function __construct(UserFinderInterface $finder, $config = [])
    {
        $this->finder = $finder;
        parent::__construct($config);
    }
}

$container = new Container;
$container->set('yii\db\Connection', [
    'dsn' => '...',
]);
$container->set('app\models\UserFinderInterface', [
    'class' => 'app\models\UserFinder',
]);
$container->set('userLister', 'app\models\UserLister');

$lister = $container->get('userLister');

// which is equivalent to:

$db = new \yii\db\Connection(['dsn' => '...']);
$finder = new UserFinder($db);
$lister = new UserLister($finder);

For more details and usage information on Container, see the guide article on di-containers.

Properties

Property	Type	Description	Defined by
$behaviors read-only	array<yii\base\Behavior<static>>	List of behaviors attached to this component.	yii\base\Component
$definitions	array	The list of the object definitions or the loaded shared objects (type or ID => definition or instance).	Container
$resolveArrays write-only	bool	Whether to attempt to resolve elements in array dependencies.	Container
$singleton write-only	string	Class name, interface name or alias name	Container
$singletons write-only	array	Array of singleton definitions.	Container

Methods

Method	Description	Defined by
__construct()	Constructor.	yii\base\BaseObject
__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
__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() static	Returns the fully qualified name of this class.	yii\base\BaseObject
clear()	Removes the definition for the specified name.	Container
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
get()	Returns an instance of the requested class.	Container
getBehavior()	Returns the named behavior object.	yii\base\Component
getBehaviors()	Returns all behaviors attached to this component.	yii\base\Component
getDefinitions()	Returns the list of the object definitions or the loaded shared objects.	Container
has()	Returns a value indicating whether the container has the definition of the specified name.	Container
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
hasSingleton()	Returns a value indicating whether the given name corresponds to a registered singleton.	Container
init()	Initializes the object.	yii\base\BaseObject
invoke()	Invoke a callback with resolving dependencies in parameters.	Container
off()	Detaches an existing event handler from this component.	yii\base\Component
on()	Attaches an event handler to an event.	yii\base\Component
resolveCallableDependencies()	Resolve dependencies for a function.	Container
set()	Registers a class definition with this container.	Container
setDefinitions()	Registers class definitions within this container.	Container
setResolveArrays()		Container
setSingleton()	Registers a class definition with this container and marks the class as a singleton class.	Container
setSingletons()	Registers class definitions as singletons within this container by calling setSingleton().	Container
trigger()	Triggers an event.	yii\base\Component
build() protected	Creates an instance of the specified class.	Container
getDependencies() protected	Returns the dependencies of the specified class.	Container
mergeParams() protected	Merges the user-specified constructor parameters with the ones registered via set().	Container
normalizeDefinition() protected	Normalizes the class definition.	Container
resolveDependencies() protected	Resolves dependencies by replacing them with the actual object instances.	Container

Property details

$singletons

public array $singletons

Array of singleton definitions.

See setDefinitions() for allowed formats of array.

Access

Write-only (virtual property).

Method details

clear()

public function clear(string $class): mixed

Removes the definition for the specified name.

Parameters

Parameter	Type	Description
$class	string	Class name, interface name or alias name

Returns

mixed

get()

public function get(string|class-string<yii\di\T>|yii\di\Instance $class, array $params = [], array $config = []): ($class is class-string<yii\di\T> ? yii\di\T : object)

Returns an instance of the requested class.

You may provide constructor parameters ($params) and object configurations ($config) that will be used during the creation of the instance.

If the class implements Configurable, the $config parameter will be passed as the last parameter to the class constructor; Otherwise, the configuration will be applied after the object is instantiated.

Note that if the class is declared to be singleton by calling setSingleton(), the same instance of the class will be returned each time this method is called. In this case, the constructor parameters and object configurations will be used only if the class is instantiated the first time.

Parameters

Parameter	Type	Description
$class	string|class-string<yii\di\T>|Instance	The class Instance, name, or an alias name (e.g. foo) that was previously registered via set() or setSingleton().
$params	array	A list of constructor parameter values. Use one of two definitions: - Parameters as name-value pairs, for example: ['posts' => PostRepository::class]. - Parameters in the order they appear in the constructor declaration. If you want to skip some parameters, you should index the remaining ones with the integers that represent their positions in the constructor parameter list. Dependencies indexed by name and by position in the same array are not allowed.
$config	array	A list of name-value pairs that will be used to initialize the object properties.

Returns

($class is class-string<yii\di\T> ? yii\di\T : object): An instance of the requested class.

Throws

• yii\base\InvalidConfigException: if the class cannot be recognized or correspond to an invalid definition
• NotInstantiableException: If resolved to an abstract class or an interface (since 2.0.9)

getDefinitions()

public function getDefinitions(): array

Returns the list of the object definitions or the loaded shared objects.

Returns

array: The list of the object definitions or the loaded shared objects (type or ID => definition or instance).

has()

public function has(string $class): bool

Returns a value indicating whether the container has the definition of the specified name.

Parameters

Parameter	Type	Description
$class	string	Class name, interface name or alias name

Returns

bool: Whether the container has the definition of the specified name.

See also

• set()

hasSingleton()

public function hasSingleton(string $class, bool $checkInstance = false): bool

Returns a value indicating whether the given name corresponds to a registered singleton.

Parameters

Parameter	Type	Description
$class	string	Class name, interface name or alias name
$checkInstance	bool	Whether to check if the singleton has been instantiated.

Returns

bool: Whether the given name corresponds to a registered singleton. If $checkInstance is true, the method should return a value indicating whether the singleton has been instantiated.

invoke()

public function invoke(callable $callback, array $params = []): mixed

Invoke a callback with resolving dependencies in parameters.

This method allows invoking a callback and let type hinted parameter names to be resolved as objects of the Container. It additionally allows calling function using named parameters.

For example, the following callback may be invoked using the Container to resolve the formatter dependency:

$formatString = function($string, \yii\i18n\Formatter $formatter) {
   // ...
}
Yii::$container->invoke($formatString, ['string' => 'Hello World!']);

This will pass the string 'Hello World!' as the first param, and a formatter instance created by the DI container as the second param to the callable.

Parameters

Parameter	Type	Description
$callback	callable	Callable to be invoked.
$params	array	The array of parameters for the function. This can be either a list of parameters, or an associative array representing named function parameters.

Returns

mixed: The callback return value.

Throws

• yii\base\InvalidConfigException: if a dependency cannot be resolved or if a dependency cannot be fulfilled.
• NotInstantiableException: If resolved to an abstract class or an interface (since 2.0.9)

Since

2.0.7

resolveCallableDependencies()

public function resolveCallableDependencies(callable $callback, array $params = []): array

Resolve dependencies for a function.

This method can be used to implement similar functionality as provided by invoke() in other components.

Parameters

Parameter	Type	Description
$callback	callable	Callable to be invoked.
$params	array	The array of parameters for the function, can be either numeric or associative.

Returns

array: The resolved dependencies.

Throws

• yii\base\InvalidConfigException: if a dependency cannot be resolved or if a dependency cannot be fulfilled.
• NotInstantiableException: If resolved to an abstract class or an interface (since 2.0.9)

Since

2.0.7

set()

public function set(string $class, mixed $definition = [], array $params = []): $this

Registers a class definition with this container.

For example,

// register a class name as is. This can be skipped.
$container->set('yii\db\Connection');

// register an interface
// When a class depends on the interface, the corresponding class
// will be instantiated as the dependent object
$container->set('yii\mail\MailInterface', 'yii\swiftmailer\Mailer');

// register an alias name. You can use $container->get('foo')
// to create an instance of Connection
$container->set('foo', 'yii\db\Connection');

// register a class with configuration. The configuration
// will be applied when the class is instantiated by get()
$container->set('yii\db\Connection', [
    'dsn' => 'mysql:host=127.0.0.1;dbname=demo',
    'username' => 'root',
    'password' => '',
    'charset' => 'utf8',
]);

// register an alias name with class configuration
// In this case, a "class" element is required to specify the class
$container->set('db', [
    'class' => 'yii\db\Connection',
    'dsn' => 'mysql:host=127.0.0.1;dbname=demo',
    'username' => 'root',
    'password' => '',
    'charset' => 'utf8',
]);

// register a PHP callable
// The callable will be executed when $container->get('db') is called
$container->set('db', function ($container, $params, $config) {
    return new \yii\db\Connection($config);
});

If a class definition with the same name already exists, it will be overwritten with the new one. You may use has() to check if a class definition already exists.

Parameters

Parameter	Type	Description
$class	string	Class name, interface name or alias name
$definition	mixed	The definition associated with $class. It can be one of the following: - a PHP callable: The callable will be executed when get() is invoked. The signature of the callable should be function ($container, $params, $config), where $params stands for the list of constructor parameters, $config the object configuration, and $container the container object. The return value of the callable will be returned by get() as the object instance requested. - a configuration array: the array contains name-value pairs that will be used to initialize the property values of the newly created object when get() is called. The class element stands for the class of the object to be created. If class is not specified, $class will be used as the class name. - a string: a class name, an interface name or an alias name.
$params	array	The list of constructor parameters. The parameters will be passed to the class constructor when get() is called.

Returns

$this: The container itself

setDefinitions()

public function setDefinitions(array $definitions): mixed

Registers class definitions within this container.

Parameters

Parameter	Type	Description
$definitions	array	Array of definitions. There are two allowed formats of array. The first format: - key: class name, interface name or alias name. The key will be passed to the set() method as a first argument $class. - value: the definition associated with $class. Possible values are described in set() documentation for the $definition parameter. Will be passed to the set() method as the second argument $definition. Example: $container->setDefinitions([ ‘yii\web\Request’ => ‘app\components\Request’, ‘yii\web\Response’ => [ ‘class’ => ‘app\components\Response’, ‘format’ => ‘json’ ], ‘foo\Bar’ => function () { $qux = new Qux; $foo = new Foo($qux); return new Bar($foo); } ]); The second format: - key: class name, interface name or alias name. The key will be passed to the set() method as a first argument $class. - value: array of two elements. The first element will be passed the set() method as the second argument $definition, the second one — as $params. Example: $container->setDefinitions([ ‘foo\Bar’ => [ [‘class’ => ‘app\Bar’], [Instance::of(‘baz’)] ] ]);

Returns

mixed

Since

2.0.11

See also

• set() (to know more about possible values of definitions)

setResolveArrays()

public function setResolveArrays(bool $value): mixed

Parameters

Parameter	Type	Description
$value	bool	Whether to attempt to resolve elements in array dependencies

Returns

mixed

Since

2.0.37

setSingleton()

public function setSingleton(string $class, mixed $definition = [], array $params = []): $this

Registers a class definition with this container and marks the class as a singleton class.

This method is similar to set() except that classes registered via this method will only have one instance. Each time get() is called, the same instance of the specified class will be returned.

Parameters

Parameter	Type	Description
$class	string	Class name, interface name or alias name
$definition	mixed	The definition associated with $class. See set() for more details.
$params	array	The list of constructor parameters. The parameters will be passed to the class constructor when get() is called.

Returns

$this: The container itself

See also

• set()

setSingletons()

public function setSingletons(array $singletons): mixed

Registers class definitions as singletons within this container by calling setSingleton().

Parameters

Parameter	Type	Description
$singletons	array	Array of singleton definitions. See setDefinitions() for allowed formats of array.

Returns

mixed

Since

2.0.11

See also

• setDefinitions() (for allowed formats of $singletons parameter)
• setSingleton() (to know more about possible values of definitions)

build()

protected function build(class-string<yii\di\T> $class, array $params, array $config): yii\di\T

Creates an instance of the specified class.

This method will resolve dependencies of the specified class, instantiate them, and inject them into the new instance of the specified class.

Parameters

Parameter	Type	Description
$class	class-string<yii\di\T>	The class name
$params	array	Constructor parameters
$config	array	Configurations to be applied to the new instance

Returns

yii\di\T: The newly created instance of the specified class

Throws

• NotInstantiableException: If resolved to an abstract class or an interface (since 2.0.9)

getDependencies()

protected function getDependencies(class-string<yii\di\T> $class): array{ReflectionClass<yii\di\T>, array<string, mixed>}

Returns the dependencies of the specified class.

Parameters

Parameter	Type	Description
$class	class-string<yii\di\T>	Class name, interface name or alias name

Returns

array{ReflectionClass<yii\di\T>, array<string, mixed>}: The dependencies of the specified class.

Throws

• NotInstantiableException: if a dependency cannot be resolved or if a dependency cannot be fulfilled.

mergeParams()

protected function mergeParams(string $class, array $params): array

Merges the user-specified constructor parameters with the ones registered via set().

Parameters

Parameter	Type	Description
$class	string	Class name, interface name or alias name
$params	array	The constructor parameters

Returns

array: The merged parameters

normalizeDefinition()

protected function normalizeDefinition(string $class, string|array|callable $definition): array

Normalizes the class definition.

Parameters

Parameter	Type	Description
$class	string	Class name
$definition	string|array|callable	The class definition

Returns

array: The normalized class definition

Throws

• yii\base\InvalidConfigException: if the definition is invalid.

resolveDependencies()

protected function resolveDependencies(array $dependencies, ReflectionClass<object>|null $reflection = null): array

Resolves dependencies by replacing them with the actual object instances.

Parameters

Parameter	Type	Description
$dependencies	array	The dependencies
$reflection	ReflectionClass<object>|null	The class reflection associated with the dependencies

Returns

array: The resolved dependencies

Throws

• yii\base\InvalidConfigException: if a dependency cannot be resolved or if a dependency cannot be fulfilled.