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Custom Annotation Classes

If you want to define your own annotations you just have to group them in a namespace and register this namespace in the AnnotationRegistry. Annotation classes have to contain a class-level docblock with the text @Annotation:

namespace MyCompany\Annotations;

/** @Annotation */
class Bar
{
    // some code
}

Inject annotation values

The annotation parser check if the annotation constructor has arguments, if so then we will pass the value array, otherwise will try to inject values into public properties directly:

namespace MyCompany\Annotations;

/**
 * @Annotation
 *
 * Some Annotation using a constructor
 */
class Bar
{
    private $foo;

    public function __construct(array $values)
    {
        $this->foo = $values['foo'];
    }
}

/**
 * @Annotation
 *
 * Some Annotation without a constructor
 */
class Foo
{
    public $bar;
}

Annotation Target

@Target indicates the kinds of class element to which an annotation type is applicable. Then you could define one or more targets:

• CLASS Allowed in the class docblock
• PROPERTY Allowed in the property docblock
• METHOD Allowed in the method docblock
• ALL Allowed in the class, property and method docblock
• ANNOTATION Allowed inside other annotations

If the annotations is not allowed in the current context you got an AnnotationException

namespace MyCompany\Annotations;

/**
 * @Annotation
 * @Target({"METHOD","PROPERTY"})
 */
class Bar
{
    // some code
}

/**
 * @Annotation
 * @Target("CLASS")
 */
class Foo
{
    // some code
}

Attribute types

Annotation parser check the given parameters using the phpdoc annotation @var, The data type could be validated using the @var annotation on the annotation properties or using the annotations @Attributes and @Attribute.

If the data type not match you got an AnnotationException

namespace MyCompany\Annotations;

/**
 * @Annotation
 * @Target({"METHOD","PROPERTY"})
 */
class Bar
{
    /** @var mixed */
    public $mixed;

    /** @var boolean */
    public $boolean;

    /** @var bool */
    public $bool;

    /** @var float */
    public $float;

    /** @var string */
    public $string;

    /** @var integer */
    public $integer;

    /** @var array */
    public $array;

    /** @var SomeAnnotationClass */
    public $annotation;

    /** @var array<integer> */
    public $arrayOfIntegers;

    /** @var array<SomeAnnotationClass> */
    public $arrayOfAnnotations;
}

/**
 * @Annotation
 * @Target({"METHOD","PROPERTY"})
 * @Attributes({
 *   @Attribute("stringProperty", type = "string"),
 *   @Attribute("annotProperty",  type = "SomeAnnotationClass"),
 * })
 */
class Foo
{
    public function __construct(array $values)
    {
        $this->stringProperty = $values['stringProperty'];
        $this->annotProperty = $values['annotProperty'];
    }

    // some code
}

Annotation Required

@Required indicates that the field must be specified when the annotation is used. If it is not used you get an AnnotationException stating that this value can not be null.

Declaring a required field:

/**
 * @Annotation
 * @Target("ALL")
 */
class Foo
{
    /** @Required */
    public $requiredField;
}

Usage:

/** @Foo(requiredField="value") */
public $direction;                  // Valid

 /** @Foo */
public $direction;                  // Required field missing, throws an AnnotationException

Enumerated values

• An annotation property marked with @Enum is a field that accept a fixed set of scalar values.
• You should use @Enum fields any time you need to represent fixed values.
• The annotation parser check the given value and throws an AnnotationException if the value not match.

Declaring an enumerated property:

/**
 * @Annotation
 * @Target("ALL")
 */
class Direction
{
    /**
     * @Enum({"NORTH", "SOUTH", "EAST", "WEST"})
     */
    public $value;
}

Annotation usage:

/** @Direction("NORTH") */
public $direction;                  // Valid value

 /** @Direction("NORTHEAST") */
public $direction;                  // Invalid value, throws an AnnotationException

Constants

The use of constants and class constants are available on the annotations parser.

The following usage are allowed:

namespace MyCompany\Entity;

use MyCompany\Annotations\Foo;
use MyCompany\Annotations\Bar;
use MyCompany\Entity\SomeClass;

/**
 * @Foo(PHP_EOL)
 * @Bar(Bar::FOO)
 * @Foo({SomeClass::FOO, SomeClass::BAR})
 * @Bar({SomeClass::FOO_KEY = SomeClass::BAR_VALUE})
 */
class User
{
}

Be careful with constants and the cache !

Usage

Using the library API is simple. Using the annotations described in the previous section you can now annotate other classes with your annotations:

namespace MyCompany\Entity;

use MyCompany\Annotations\Foo;
use MyCompany\Annotations\Bar;

/**
 * @Foo(bar="foo")
 * @Bar(foo="bar")
 */
class User
{
}

Now we can write a script to get the annotations above:

$reflClass = new ReflectionClass('MyCompany\Entity\User');
$classAnnotations = $reader->getClassAnnotations($reflClass);

foreach ($classAnnotations AS $annot) {
    if ($annot instanceof \MyCompany\Annotations\Foo) {
        echo $annot->bar; // prints "foo";
    } else if ($annot instanceof \MyCompany\Annotations\Bar) {
        echo $annot->foo; // prints "bar";
    }
}

You have a complete API for retrieving annotation class instances from a class, property or method docblock:

Reader API

Access all annotations of a class

public function getClassAnnotations(\ReflectionClass $class);

Access one annotation of a class

public function getClassAnnotation(\ReflectionClass $class, $annotationName);

Access all annotations of a method

public function getMethodAnnotations(\ReflectionMethod $method);

Access one annotation of a method

public function getMethodAnnotation(\ReflectionMethod $method, $annotationName);

Access all annotations of a property

public function getPropertyAnnotations(\ReflectionProperty $property);

Access one annotation of a property

public function getPropertyAnnotation(\ReflectionProperty $property, $annotationName);