I have a simple class like this:
class MyClass {
public $color = 'red';
public $width = 200;
public $height = 100;
public function getValues(array $properties) {
return array_map(function($property) {
return $this->$property;
}, $properties);
}
}
I would like to do the following:
$values = (new MyClass)->getValues(['width', 'height']);
Where $values would end up containing this array: [200, 100].
The following example above works perfectly fine, so my question is:
How can we simplify the getValues() method? Surely there is a simpler way to achieve this?
Requirements:
It should be functional (no for/while loops). <- this criteria is met in my example
It should not use a callback function. <- this criteria is not met in my example
You could store your class-variables in an array and then use array_intersect_key() and array_flip() to achieve that. Here is an example.
class MyClass {
public $values = [
'color' => 'red',
'width' => '200',
'heigth' => '100'
];
public function getValues (array $properties) {
return array_intersect_key ($this -> values, array_flip ($properties));
}
//EDIT 2
public function set_value ($key, $value) {
$this -> values[$key] = $value;
}
}
//EDIT (thanks to mae)
It is also possible to generate an array of the class properties with ReflectionClass() and getProperties().
//EDIT (thanks to Nigel Ren)
Instead of Reflection it is possible to use get_object_vars() to achieve the same output.
class MyClass {
public $color = 'red';
public $width = '200';
public $heigth = '100';
public function getValues (array $properties) {
return array_intersect_key (get_object_vars ($this), array_flip ($properties));
}
}
Consider a new approach:
class MyClass
{
public $prop = array();
public function set($key, $value)
{
$this->prop[$key] = $value;
}
public function get($key)
{
return $this->prop[$key];
}
}
$o = new MyClass();
$o->set('color', 'blue');
$o->set('pi', 3.14);
$o->get('color'); // blue
$o->get('pi'); // 3.14
I've been fooling with ArrayAccess and PHP's magic (__get, __set) for awhile now, and I'm stuck.
I'm trying to implement a class in which some properties, which are arrays, are read only. They will be set initially by the constructor, but should not be modifiable thereafter.
Using __get magic by reference, I can access array elements arbitrarily deep in the properties, and I was thinking I can throw exceptions when those properties are targeted via __set.
The problem is though, when I'm accessing the value of an array element, PHP is calling __get to return that part of the array by reference, and I have no knowledge of whether or not its a read or write action.
(The worst part is I knew this going in, but have been fooling with ArrayAccess as a possible workaround solution, given the properties were instances of an implemented object)
Simple example:
class Test{
public function &__get($key){
echo "[READ:{$key}]\n";
}
public function __set($key, $value){
echo "[WRITE:{$key}={$value}]\n";
}
}
$test = new Test;
$test->foo;
$test->foo = 'bar';
$test->foo['bar'];
$test->foo['bar'] = 'zip';
And the output:
[READ:foo]
[WRITE:foo=bar]
[READ:foo]
[READ:foo] // here's the problem
Realistically, I only need the value foo (as per my example) anyways, but I need to know it's a write action, not read.
I've already half accepted that this cannot be achieved, but I'm still hopeful. Does anyone have any idea how what I'm looking to accomplish can be done?
I was considering some possible workarounds with ArrayAccess, but so far as I can tell, I'll end up back at this spot, given I'm going to use the property notation that invokes __get.
Update: Another fun day with ArrayAccess.
(This is a different issue, but I suppose it works in. Posting just for kicks.)
class Mf_Params implements ArrayAccess{
private $_key = null;
private $_parent = null;
private $_data = array();
private $_temp = array();
public function __construct(Array $data = array(), $key = null, self $parent = null){
$this->_parent = $parent;
$this->_key = $key;
foreach($data as $key => $value){
$this->_data[$key] = is_array($value)
? new self($value, $key, $this)
: $value;
}
}
public function toArray(){
$array = array();
foreach($this->_data as $key => $value){
$array[$key] = $value instanceof self
? $value->toArray()
: $value;
}
return $array;
}
public function offsetGet($offset){
if(isset($this->_data[$offset])){
return $this->_data[$offset];
}
// if offset not exist return temp instance
return $this->_temp[$offset] = new self(array(), $offset, $this);
}
public function offsetSet($offset, $value){
$child = $this;
// copy temp instances to data after array reference chain
while(!is_null($parent = $child->_parent) && $parent->_temp[$child->_key] === $child){
$parent->_data[$child->_key] = $parent->_temp[$child->_key];
$child = $parent;
}
// drop temp
foreach($child->_temp as &$temp){
unset($temp);
}
if(is_null($offset)){
$this->_data[] = is_array($value)
? new self($value, null, $this)
: $value;
}else{
$this->_data[$offset] = is_array($value)
? new self($value, $offset, $this)
: $value;
}
}
public function offsetExists($offset){
return isset($this->_data[$offset]);
}
public function offsetUnset($offset){
unset($this->_data[$offset]);
}
}
You need to use a second class, implementing ArrayAccess, to use instead of your arrays. Then you will be able to control what is added to the array with the offsetSet() method:
class ReadOnlyArray implements ArrayAccess {
private $container = array();
public function __construct(array $array) {
$this->container = $array;
}
public function offsetSet($offset, $value) {
throw new Exception('Read-only');
}
public function offsetExists($offset) {
return isset($this->container[$offset]);
}
public function offsetUnset($offset) {
unset($this->container[$offset]);
}
public function offsetGet($offset) {
if (! array_key_exists($offset, $this->container)) {
throw new Exception('Undefined offset');
}
return $this->container[$offset];
}
}
You can then initialize your ReadOnlyArray with your original array:
$readOnlyArray = new ReadOnlyArray(array('foo', 'bar'));
You could not return by ref, which would solve the problem of changability, but would not allow changing of some values that are allowed to be changed.
Alternatively you need to wrap every returned array in ArrayAccess, too - and forbid write access there.
Is it possible to decode a json string to an object other than stdClass?
Not automatically. But you can do it the old fashioned route.
$data = json_decode($json, true);
$class = new Whatever();
foreach ($data as $key => $value) $class->{$key} = $value;
Or alternatively, you could make that more automatic:
class Whatever {
public function set($data) {
foreach ($data AS $key => $value) $this->{$key} = $value;
}
}
$class = new Whatever();
$class->set($data);
Edit: getting a little fancier:
class JSONObject {
public function __construct($json = false) {
if ($json) $this->set(json_decode($json, true));
}
public function set($data) {
foreach ($data AS $key => $value) {
if (is_array($value)) {
$sub = new JSONObject;
$sub->set($value);
$value = $sub;
}
$this->{$key} = $value;
}
}
}
// These next steps aren't necessary. I'm just prepping test data.
$data = array(
"this" => "that",
"what" => "who",
"how" => "dy",
"multi" => array(
"more" => "stuff"
)
);
$jsonString = json_encode($data);
// Here's the sweetness.
$class = new JSONObject($jsonString);
print_r($class);
We built JsonMapper to map JSON objects onto our own model classes automatically. It works fine with nested/child objects.
It only relies on docblock type information for mapping, which most class properties have anyway:
<?php
$mapper = new JsonMapper();
$contactObject = $mapper->map(
json_decode(file_get_contents('http://example.org/contact.json')),
new Contact()
);
?>
You can do it - it's a kludge but totally possible. We had to do when we started storing things in couchbase.
$stdobj = json_decode($json_encoded_myClassInstance); //JSON to stdClass
$temp = serialize($stdobj); //stdClass to serialized
// Now we reach in and change the class of the serialized object
$temp = preg_replace('#^O:8:"stdClass":#','O:7:"MyClass":',$temp);
// Unserialize and walk away like nothing happend
$myClassInstance = unserialize($temp); // Presto a php Class
In our benchmarks this was way faster than trying to iterate through all the class variables.
Caveat: Won't work for nested objects other than stdClass
Edit: keep in mind the data source, it's strongly recommended that you don't do this withe untrusted data from users without a very carful analysis of the risks.
You could use Johannes Schmitt's Serializer library.
$serializer = JMS\Serializer\SerializerBuilder::create()->build();
$object = $serializer->deserialize($jsonData, 'MyNamespace\MyObject', 'json');
In the latest version of the JMS serializer the syntax is:
$serializer = SerializerBuilder::create()->build();
$object = $serializer->deserialize($jsonData, MyObject::class, 'json');
I'm surprised no one mentioned this, yet.
Use the Symfony Serializer component: https://symfony.com/doc/current/components/serializer.html
Serializing from Object to JSON:
use App\Model\Person;
$person = new Person();
$person->setName('foo');
$person->setAge(99);
$person->setSportsperson(false);
$jsonContent = $serializer->serialize($person, 'json');
// $jsonContent contains {"name":"foo","age":99,"sportsperson":false,"createdAt":null}
echo $jsonContent; // or return it in a Response
Deserializing from JSON to Object: (this example uses XML just to demonstrate the flexibility of formats)
use App\Model\Person;
$data = <<<EOF
<person>
<name>foo</name>
<age>99</age>
<sportsperson>false</sportsperson>
</person>
EOF;
$person = $serializer->deserialize($data, Person::class, 'xml');
You can do it in below way ..
<?php
class CatalogProduct
{
public $product_id;
public $sku;
public $name;
public $set;
public $type;
public $category_ids;
public $website_ids;
function __construct(array $data)
{
foreach($data as $key => $val)
{
if(property_exists(__CLASS__,$key))
{
$this->$key = $val;
}
}
}
}
?>
For more details visit
create-custom-class-in-php-from-json-or-array
You can make a wrapper for your object and make the wrapper look like it is the object itself. And it will work with multilevel objects.
<?php
class Obj
{
public $slave;
public function __get($key) {
return property_exists ( $this->slave , $key ) ? $this->slave->{$key} : null;
}
public function __construct(stdClass $slave)
{
$this->slave = $slave;
}
}
$std = json_decode('{"s3":{"s2":{"s1":777}}}');
$o = new Obj($std);
echo $o->s3->s2->s1; // you will have 777
No, this is not possible as of PHP 5.5.1.
The only thing possible is to have json_decode return associate arrays instead of the StdClass objects.
Use Reflection:
function json_decode_object(string $json, string $class)
{
$reflection = new ReflectionClass($class);
$instance = $reflection->newInstanceWithoutConstructor();
$json = json_decode($json, true);
$properties = $reflection->getProperties();
foreach ($properties as $key => $property) {
$property->setAccessible(true);
$property->setValue($instance, $json[$property->getName()]);
}
return $instance;
}
As Gordon says is not possible. But if you are looking for a way to obtain a string that can be decoded as an instance of a give class you can use serialize and unserialize instead.
class Foo
{
protected $bar = 'Hello World';
function getBar() {
return $this->bar;
}
}
$string = serialize(new Foo);
$foo = unserialize($string);
echo $foo->getBar();
I once created an abstract base class for this purpose. Let's call it JsonConvertible. It should serialize and deserialize the public members. This is possible using Reflection and late static binding.
abstract class JsonConvertible {
static function fromJson($json) {
$result = new static();
$objJson = json_decode($json);
$class = new \ReflectionClass($result);
$publicProps = $class->getProperties(\ReflectionProperty::IS_PUBLIC);
foreach ($publicProps as $prop) {
$propName = $prop->name;
if (isset($objJson->$propName) {
$prop->setValue($result, $objJson->$propName);
}
else {
$prop->setValue($result, null);
}
}
return $result;
}
function toJson() {
return json_encode($this);
}
}
class MyClass extends JsonConvertible {
public $name;
public $whatever;
}
$mine = MyClass::fromJson('{"name": "My Name", "whatever": "Whatever"}');
echo $mine->toJson();
Just from memory, so probably not flawless. You will also have to exclude static properties and may give derived classes the chance to make some properties ignored when serialized to/from json. I hope you get the idea, nonetheless.
JSON is a simple protocol to transfer data between various programming languages (and it's also a subset of JavaScript) which supports just certain types: numbers, strings, arrays/lists, objects/dicts. Objects are just key=value maps and Arrays are ordered lists.
So there is no way to express custom objects in a generic way. The solution is defining a structure where your program(s) will know that it's a custom object.
Here's an example:
{ "cls": "MyClass", fields: { "a": 123, "foo": "bar" } }
This could be used to create an instance of MyClass and set the fields a and foo to 123 and "bar".
I went ahead and implemented John Petit's answer, as a function(gist):
function json_decode_to(string $json, string $class = stdClass::class, int $depth = 512, int $options = 0)
{
$stdObj = json_decode($json, false, $depth, $options);
if ($class === stdClass::class) return $stdObj;
$count = strlen($class);
$temp = serialize($stdObj);
$temp = preg_replace("#^O:8:\"stdClass\":#", "O:$count:\"$class\":", $temp);
return unserialize($temp);
}
This worked perfectly for my use case. However Yevgeniy Afanasyev's response seems equally promising to me. It could be possible to have your class have an extra "constructor", like so:
public static function withJson(string $json) {
$instance = new static();
// Do your thing
return $instance;
}
This is also inspired by this answer.
EDIT: I have been using karriereat/json-decoder for some time now, and I have had absolutely no trouble with it. It is lightweight and very easily extensible. Here's an example of a binding I wrote to deserialize JSON into a Carbon/CarbonImmutable object.
All this here inspired me to a generic function:
function loadJSON($Obj, $json)
{
$dcod = json_decode($json);
$prop = get_object_vars ( $dcod );
foreach($prop as $key => $lock)
{
if(property_exists ( $Obj , $key ))
{
if(is_object($dcod->$key))
{
loadJSON($Obj->$key, json_encode($dcod->$key));
}
else
{
$Obj->$key = $dcod->$key;
}
}
}
}
to be called in class declaration:
class Bar{public $bar = " Boss";}
class Bas
{
public $ber ;
public $bas=" Boven";
public function __construct()
{$this->ber = new Bar;}
}
class Baz
{
public $bes ;
public $baz=" Baaz";
public function __construct()
{$this->bes = new Bas;}
}
$Bazjson = '{"bes":{"ber":{"bar":"Baas"}}}';
$Bazobj = new Baz;
loadJSON($Bazobj, $Bazjson);
var_dump($Bazobj);
This worked for me, especially for if you don't have setters or named properties in the target class
function cast($jsonstring, $class)
{
//$class is a string like 'User'
$json= json_decode($jsonstring,true); //array
$reflection = new ReflectionClass($class);
$instance = $reflection->newInstanceWithoutConstructor();
$keys = array_keys($json);
foreach ($keys as $key => $property) {
$instance->{$property} =$json[$property];
}
// print_r($instance);
return $instance;
}
Not directly, but if the class has a constructor with parameter names that match the keys in the JSON object, you can simply decode the JSON into an associative array and pass it to the constructor via the '...' (argument unpacking) operator:
<?php
class MyClass {
public function __construct(
public int $id,
public string $name,
public array $attributes,
){}
}
$json = '{"name":"foo","id":42,"attributes":{"color":"red"}}';
$object = new MyClass(...json_decode($json, true));
print_r($object);
Output:
MyClass Object
(
[id] => 42
[name] => foo
[attributes] => Array
(
[color] => red
)
)
However, in practice, there is often some additional mapping to do, especially sub-objects that need to be recursively decoded too. So usually it is better to have a static fromArray function in each class that pre-processes the json-decoded array before passing the result to the constructor:
class Part {
public function __construct(public float $weight){}
public static function fromArray(array $data): self {
return new self(...$data);
}
}
class System {
public function __construct(
public string $name,
public Part $mainPart,
public array $otherParts,
){}
public static function fromArray(array $data): self {
$data['mainPart'] = Part::fromArray($data['mainPart']);
$data['otherParts'] = array_map(Part::fromArray(...), $data['otherParts']); // php 8.1
return new self(...$data);
}
}
$json = '{"name":"foo","mainPart":{"weight":2},"otherParts":[{"weight":1}, {"weight":0.5}]}';
$object = System::fromArray(json_decode($json, true));
This question already exists:
Closed 11 years ago.
Possible Duplicate:
Any way to access array directly after method call?
In C# and other languages, I can do something like this
$value = $obj->getArray()[0];
But not in PHP. Any workarounds or am I doomed to do this all the time?
$array = $obj->getArray();
$value = $array[0];
No, you can't do it without using array_shift (Which only gets the first element). If you want to access the third or fourth, most likely you'd want to do a function like this:
function elemnt($array, $element)
{
return $array[$element];
}
$value = element($obj->getArray(), 4);
Also, see this question, as it is an exact duplicate: Any way to access array directly after method call?
I think you are doomed to do it that way :(
You can do this:
$res = array_pop(array_slice(somefunc(1), $i, 1));
If this is a one-off or occasional thing where the situation in your example holds true, and you're retrieving the first element of the return array, you can use:
$value = array_shift($obj->getArray());
If this is a pervasive need and you often need to retrieve elements other than the first (or last, for which you can use array_pop()), then I'd arrange to have a utility function available like so:
function elementOf($array, $index = 0) {
return $array[$index];
}
$value = elementOf($obj->getArray());
$otherValue = elementOf($obj->getArray(), 2);
Well, maybe this could help you, in php spl, pretty usefull, you can make you a Special Array for you:
<?php
class OArray extends ArrayObject{
public function __set($name, $val) {
$this[$name] = $val;
}
public function __get($name) {
return $this[$name];
}
}
class O{
function __construct(){
$this->array = new OArray();
$this->array[] = 1;
$this->array[] = 2;
$this->array[] = 3;
$this->array[] = 4;
}
function getArray(){
return $this->array;
}
}
$o = new O();
var_dump( $o->getArray()->{1} );
<?php
class MyArray implements Iterator ,ArrayAccess
{
private $var = array();
//-- ArrayAccess
public function offsetSet($offset, $value) {
if (is_null($offset)) {
$this->var[] = $value;
} else {
$this->var[$offset] = $value;
}
}
public function offsetExists($offset) {
return isset($this->var[$offset]);
}
public function offsetUnset($offset) {
unset($this->var[$offset]);
}
public function offsetGet($offset) {
return isset($this->var[$offset]) ? $this->var[$offset] : null;
}//-- Iterator
public function __construct($array){
if (is_array($array)) {
$this->var = $array;
}
}
public function rewind() {
reset($this->var);
}
public function current() {
return current($this->var);
}
public function key() {
return key($this->var);
}
public function next() {
return next($this->var);
}
public function valid() {
return ($this->current() !== false);
}
}
$values = array(
"one" => 1,
"two" => 2,
"three" => 3,
);
$it = new MyArray($values);
foreach ($it as $a => $b) {
print "$a: $b<br>";
}
echo $it["one"]."<br>";?>
I need to serialize a proxy class. The class uses __set and __get to store values in an array. I want the serialization to look like it is just a flat object. In other words, my class looks like:
class Proxy
{
public $data = array();
public function __get($name)
{
return $data[$name]
}
}
and I want a foreach loop to return all the keys and values in $data, when I say:
foreach($myProxy as $key)
Is this possible?
class Proxy implements IteratorAggregate
{
public $data = array();
public function __get($name)
{
return $data[$name];
}
public function getIterator()
{
$o = new ArrayObject($this->data);
return $o->getIterator();
}
}
$p = new Proxy();
$p->data = array(2, 4, 6);
foreach ($p as $v)
{
echo $v;
}
Output is: 246.
See Object Iteration in the PHP docs for more details.
You want to implement the SPL iterator interface
Something like this:
class Proxy implements Iterator
{
public $data = array();
public function __get($name)
{
return $data[$name]
}
function rewind()
{
reset($this->data);
$this->valid = true;
}
function current()
{
return current($this->data)
}
function key()
{
return key($this->data)
}
function next() {
next($this->data);
}
function valid()
{
return key($this->data) !== null;
}
}