发布于 2015-08-27 16:43:25 | 160 次阅读 | 评论: 0 | 来源: 网络整理
The PropertyAccess component provides function to read and write from/to an object or array using a simple string notation.
You can install the component in two different ways:
symfony/property-access on Packagist);The entry point of this component is the PropertyAccess::createPropertyAccessor factory. This factory will create a new instance of the PropertyAccessor class with the default configuration:
use SymfonyComponentPropertyAccessPropertyAccess; $accessor = PropertyAccess::createPropertyAccessor();
2.3 新版功能: The createPropertyAccessor() method was introduced in Symfony 2.3. Previously, it was called getPropertyAccessor().
You can read an array with the PropertyAccessor::getValue method. This is done using the index notation that is used in PHP:
// ...
$person = array(
'first_name' => 'Wouter',
);
echo $accessor->getValue($person, '[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'
The getValue method is a very robust method, and you can see all of its features when working with objects.
To read from properties, use the “dot” notation:
// ... $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'
警告
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.
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'
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:
// ...
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
__get() Method¶The getValue method can also use the magic __get method:
// ...
class Person
{
private $children = array(
'Wouter' => array(...),
);
public function __get($id)
{
return $this->children[$id];
}
}
$person = new Person();
echo $accessor->getValue($person, 'Wouter'); // array(...)
__call() Method¶At last, getValue can use the magic __call method, but you need to enable this feature by using PropertyAccessorBuilder:
// ...
class Person
{
private $children = array(
'wouter' => array(...),
);
public function __call($name, $args)
{
$property = lcfirst(substr($name, 3));
if ('get' === substr($name, 0, 3)) {
return isset($this->children[$property])
? $this->children[$property]
: null;
} elseif ('set' === substr($name, 0, 3)) {
$value = 1 == count($args) ? $args[0] : null;
$this->children[$property] = $value;
}
}
}
$person = new Person();
// Enable magic __call
$accessor = PropertyAccess::createPropertyAccessorBuilder()
->enableMagicCall()
->getPropertyAccessor();
echo $accessor->getValue($person, 'wouter'); // array(...)
2.3 新版功能: The use of magic __call() method was introduced in Symfony 2.3.
警告
The __call feature is disabled by default, you can enable it by calling PropertyAccessorBuilder::enableMagicCallEnabled see Enable other Features.
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:
// ... $person = array(); $accessor->setValue($person, '[first_name]', 'Wouter'); echo $accessor->getValue($person, '[first_name]'); // 'Wouter' // or // echo $person['first_name']; // 'Wouter'
The setValue method has the same features as the getValue method. You can use setters, the magic __set method 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());
You can also use __call to set values but you need to enable the feature, see Enable other Features.
// ...
class Person
{
private $children = array();
public function __call($name, $args)
{
$property = lcfirst(substr($name, 3));
if ('get' === substr($name, 0, 3)) {
return isset($this->children[$property])
? $this->children[$property]
: null;
} elseif ('set' === substr($name, 0, 3)) {
$value = 1 == count($args) ? $args[0] : null;
$this->children[$property] = $value;
}
}
}
$person = new Person();
// Enable magic __call
$accessor = PropertyAccess::createPropertyAccessorBuilder()
->enableMagicCall()
->getPropertyAccessor();
$accessor->setValue($person, 'wouter', array(...));
echo $person->getWouter(); // array(...)
When you want to check whether PropertyAccessor::getValue can safely be called without actually calling that method, you can use PropertyAccessor::isReadable instead:
$person = new Person();
if ($accessor->isReadable($person, 'firstName')) {
// ...
}
The same is possible for PropertyAccessor::setValue: Call the PropertyAccessor::isWritable method to find out whether a property path can be updated:
$person = new Person();
if ($accessor->isWritable($person, 'firstName')) {
// ...
}
You can also mix objects and arrays:
// ...
class Person
{
public $firstName;
private $children = array();
public function setChildren($children)
{
$this->children = $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
The PropertyAccessor can be configured to enable extra features. To do that you could use the PropertyAccessorBuilder:
// ...
$accessorBuilder = PropertyAccess::createPropertyAccessorBuilder();
// Enable magic __call
$accessorBuilder->enableMagicCall();
// Disable magic __call
$accessorBuilder->disableMagicCall();
// Check if magic __call handling is enabled
$accessorBuilder->isMagicCallEnabled(); // true or false
// At the end get the configured property accessor
$accessor = $accessorBuilder->getPropertyAccessor();
// Or all in one
$accessor = PropertyAccess::createPropertyAccessorBuilder()
->enableMagicCall()
->getPropertyAccessor();
Or you can pass parameters directly to the constructor (not the recommended way):
// ... $accessor = new PropertyAccessor(true); // this enables handling of magic __call