Created PropertyAccess component docs

Author: wouterj

components/map.rst.inc

@@ -71,6 +71,10 @@
 
   * :doc:`/components/process`
 
+* :doc:`/components/property_access/index
+
+  * :doc:`/components/property_access/introduction`
+
 * :doc:`/components/routing/index`
 
   * :doc:`/components/routing/introduction`

components/property_access/index.rst

@@ -0,0 +1,7 @@
+Property Access
+===============
+
+.. toctree::
+    :maxdepth: 2
+
+    introduction

components/property_access/introduction.rst

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+.. index::
+    single: PropertyAccess
+    single: Components; PropertyAccess
+
+The PropertyAccess Component
+============================
+
+    PropertyAccess component provides function to read and write from/to an
+    object or array using a simple string notation.
+
+.. versionadded:: 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:
+
+* Use the official Git repository (https://github.com/symfony/PropertyAccess);
+* :doc:`Install it via Composer</components/using_components>` * (``symfony/property-access`` on `Packagist`_).
+
+Usage
+-----
+
+The entry point of this component is the
+:method:`Symfony\\Component\\PropertyAccess\\PropertyAccess::getPropertyAccessor`
+factory. This factory will create a new instance of the
+:class:`Symfony\\Component\\PropertyAccess\PropertyAccessor` class with the
+default configuration::
+
+    use Symfony\Component\PropertyAccess\PropertyAccess;
+
+    $accessor = PropertyAccess:getPropertyAccessor();
+
+Reading from arrays
+-------------------
+
+You can read an array with the
+:method:`Symfony\\Component\\PropertyAccess\PropertyAccessor::getValue`
+method. This is done using the index notation that is used in PHP::
+
+    // ...
+    $person = array(
+        'first_name' => 'Wouter',
+    );
+
+    echo $accessor->getValue($persons, '[first_name]'); // 'Wouter'
+    echo $accessor->getValue($person, '[age]'); // null
+
+As you can see, the method will return ``null`` if the index does not exists.
+
+You can also use multi dimensional arrays::
+
+    // ...
+    $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. You can see all features if
+you are working with objects.
+
+Using properties
+~~~~~~~~~~~~~~~~
+
+We can read properties without the index notation, instead we use the dot
+notation::
+
+    // ...
+    $person = new Person();
+    $person->firstName = 'Wouter';
+
+    echo $accessor->getValue($person, 'first_name'); // 'Wouter'
+
+    $child = new Person();
+    $child->firstName = 'Bar';
+    $person->children = array($child);
+
+    echo $accessor->getValue($person, 'children[0].first_name'); // 'Bar'
+
+.. caution::
+
+    This option is the last option used by the ``PropertyAccessor``. It tries
+    to find the other options before using the property. If you have a public
+    property that have a getter to, 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``::
+
+    // ...
+    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 a isser or hasser. This method is created using the same way as
+getters, this means that you can do something like this::
+
+    // ...
+    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, the ``getValue`` can use the magic ``__get`` too::
+
+    // ...
+    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 reading an array, it can
+also write to an array. This can be achieved using the
+:method:`Symfony\\Component\\PropertyAccess\\PropertyAccessor::setValue`
+method::
+
+    // ...
+    $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`` or properties to set values::
+
+    // ...
+    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::
+
+    // ...
+    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
+
+.. _Packagist: https://packagist.org/packages/symfony/property-access