The PropertyAccess Component
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The PropertyAccess Component
The PropertyAccess component provides function to read and write from/to an object or array using a simple string notation.
2.2
The PropertyAccess component is new to Symfony 2.2. Previously, the
PropertyPath class was located in the Form component.
Installation
You can install the component in two different ways:
- Install it via Composer (
symfony/property-accesson Packagist); - Use the official Git repository (https://github.com/symfony/PropertyAccess).
Usage
The entry point of this component is the PropertyAccess::getPropertyAccessor factory. This factory will create a new instance of the PropertyAccessor class with the default configuration:
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use Symfony\Component\PropertyAccess\PropertyAccess;
$accessor = PropertyAccess::getPropertyAccessor();Reading from Arrays
You can read an array with the PropertyAccessor::getValue method. This is done using the index notation that is used in PHP:
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// ...
$person = array(
'first_name' => 'Wouter',
);
echo $accessor->getValue($person, '[first_name]'); // 'Wouter'
echo $accessor->getValue($person, '[age]'); // nullAs you can see, the method will return null if the index does not exists.
You can also use multi dimensional arrays:
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// ...
$persons = array(
array(
'first_name' => 'Wouter',
),
array(
'first_name' => 'Ryan',
)
);
echo $accessor->getValue($persons, '[0][first_name]'); // 'Wouter'
echo $accessor->getValue($persons, '[1][first_name]'); // 'Ryan'Reading from Objects
The getValue method is a very robust method, and you can see all of its
features when working with objects.
Accessing public Properties
To read from properties, use the "dot" notation:
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// ...
$person = new Person();
$person->firstName = 'Wouter';
echo $accessor->getValue($person, 'firstName'); // 'Wouter'
$child = new Person();
$child->firstName = 'Bar';
$person->children = array($child);
echo $accessor->getValue($person, 'children[0].firstName'); // 'Bar'Caution
Accessing public properties is the last option used by PropertyAccessor.
It tries to access the value using the below methods first before using
the property directly. For example, if you have a public property that
has a getter method, it will use the getter.
Using Getters
The getValue method also supports reading using getters. The method will
be created using common naming conventions for getters. It camelizes the
property name (first_name becomes FirstName) and prefixes it with
get. So the actual method becomes getFirstName:
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// ...
class Person
{
private $firstName = 'Wouter';
public function getFirstName()
{
return $this->firstName;
}
}
$person = new Person();
echo $accessor->getValue($person, 'first_name'); // 'Wouter'Using Hassers/Issers
And it doesn't even stop there. If there is no getter found, the accessor will look for an isser or hasser. This method is created using the same way as getters, this means that you can do something like this:
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// ...
class Person
{
private $author = true;
private $children = array();
public function isAuthor()
{
return $this->author;
}
public function hasChildren()
{
return 0 !== count($this->children);
}
}
$person = new Person();
if ($accessor->getValue($person, 'author')) {
echo 'He is an author';
}
if ($accessor->getValue($person, 'children')) {
echo 'He has children';
}This will produce: He is an author
Magic Methods
At last, getValue can use the magic __get method too:
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// ...
class Person
{
private $children = array(
'Wouter' => array(...),
);
public function __get($id)
{
return $this->children[$id];
}
}
$person = new Person();
echo $accessor->getValue($person, 'Wouter'); // array(...)Writing to Arrays
The PropertyAccessor class can do more than just read an array, it can
also write to an array. This can be achieved using the
PropertyAccessor::setValue
method:
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// ...
$person = array();
$accessor->setValue($person, '[first_name]', 'Wouter');
echo $accessor->getValue($person, '[first_name]'); // 'Wouter'
// or
// echo $person['first_name']; // 'Wouter'Writing to Objects
The setValue method has the same features as the getValue method. You
can use setters, the magic __set method or properties to set values:
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// ...
class Person
{
public $firstName;
private $lastName;
private $children = array();
public function setLastName($name)
{
$this->lastName = $name;
}
public function __set($property, $value)
{
$this->$property = $value;
}
// ...
}
$person = new Person();
$accessor->setValue($person, 'firstName', 'Wouter');
$accessor->setValue($person, 'lastName', 'de Jong');
$accessor->setValue($person, 'children', array(new Person()));
echo $person->firstName; // 'Wouter'
echo $person->getLastName(); // 'de Jong'
echo $person->children; // array(Person());Mixing Objects and Arrays
You can also mix objects and arrays:
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// ...
class Person
{
public $firstName;
private $children = array();
public function setChildren($children)
{
return $this->children;
}
public function getChildren()
{
return $this->children;
}
}
$person = new Person();
$accessor->setValue($person, 'children[0]', new Person);
// equal to $person->getChildren()[0] = new Person()
$accessor->setValue($person, 'children[0].firstName', 'Wouter');
// equal to $person->getChildren()[0]->firstName = 'Wouter'
echo 'Hello '.$accessor->getValue($person, 'children[0].firstName'); // 'Wouter'
// equal to $person->getChildren()[0]->firstName
