There is a bug that says that if you use fetch_object('classname') it will call the _set method before the _construct. So how do you get the object instantiated before it calls the __set method.
this Bug/Feature is an interesting PHP Flaw. It is handy in cases like this:
class MyModel {
public $id;
public $column2;
public $column3;
public function __construct() {
//work with prefilled properties from database here
}
}
$model = $mysqli->query()->fetch_object('MyModel');
and it even works in this case:
class MyModel {
public $data;
public function __construct() {
//work with $this->data here
}
public function __set($name, $value) {
$this->data[$name] = $value;
}
}
$model = $mysqli->query()->fetch_object('MyModel');
but it bites you in cases like this:
class MyModel {
public $data;
public function __construct($someOtherService) {
$this->service = $someOtherService;
}
public function __set($name, $value) {
$this->service->workWith($name, $value);
$this->data[$name] = $value;
}
}
$model = $mysqli->query()->fetch_object('MyModel');
Related
I have a class that extends from Yii2's Model and I need to declare a class public property in the constructor, but I'm hitting a problem.
When I call
class Test extends \yii\base\Model {
public function __constructor() {
$test = "test_prop";
$this->{$test} = null; // create $this->test_prop;
}
}
Yii tries to call, from what I understand, the getter method of this property, which of course doesn't exist, so I hit this exception.
Also, when I actually do $this->{$test} = null;, this method gets called.
My question is: Is there a way to declare a class public property in another way? Maybe some Reflexion trick?
You could override getter/setter, e.g. :
class Test extends \yii\base\Model
{
private $_attributes = ['test_prop' => null];
public function __get($name)
{
if (array_key_exists($name, $this->_attributes))
return $this->_attributes[$name];
return parent::__get($name);
}
public function __set($name, $value)
{
if (array_key_exists($name, $this->_attributes))
$this->_attributes[$name] = $value;
else parent::__set($name, $value);
}
}
You could also create a behavior...
Ok, I received help from one of Yii's devs. Here is the answer:
class Test extends Model {
private $dynamicFields;
public function __construct() {
$this->dynamicFields = generate_array_of_dynamic_values();
}
public function __set($name, $value) {
if (in_array($name, $this->dynamicFields)) {
$this->dynamicFields[$name] = $value;
} else {
parent::__set($name, $value);
}
}
public function __get($name) {
if (in_array($name, $this->dynamicFields)) {
return $this->dynamicFields[$name];
} else {
return parent::__get($name);
}
}
}
Note that I'm using in_array instead of array_key_exists because the dynamicFields array is a plain array, not an associative one.
EDIT: This is actually wrong. See my accepted answer.
Try to set variable in init method.
Like this:
public function init() {
$test = "test_prop";
$this->{$test} = null; // create $this->test_prop;
parent::init();
}
I'm getting value form Form class by creating object.It's working fine.But I wanna do it using static method.I tried but did not succeed.
public function display()
{
$newform=new Form();
echo "<pre>";
var_dump($newform->getAll());
var_dump($newform->get('name'));
}
<?php
class Form
{
private $value = array();
function __construct() {
// here you can use some validation or escapes
foreach($_POST as $key=>$value)
$this->value[$key] = $value;
}
public function getAll() {
return $this->value;
}
public function get($value) {
$this->value = $_POST[$value];
return $this->value;
}
}
Maybe You should just try to read PHP documentation about static keyword?
Example:
class Form {
private static $value = array();
public static function factory() {
// here you can use some validation or escapes
foreach($_POST as $key => $value) {
static::$value[$key] = $value;
}
}
public static function getAll() {
return static::$value;
}
public static function get($key) {
return static::$value[$key];
}
}
Use:
public function display() {
Form::factory();
echo "<pre>";
var_dump(Form::getAll());
var_dump(Form::get('name'));
echo "</pre>";
}
you do not declare a function as public/private/protected outside of the class
you you want to call this method statically, you may try it
<?php
function display()
{
$newform=new Form($_POST);
echo "<pre>";
var_dump(Form::getAll());
var_dump(Form::get('name'));
}
class Form
{
private static $value = array();
function __construct(){
// here you can use some validation or escapes
function __constract($array){
foreach($array as $key=>$value)
self::$value[$key] = $value;
}
}
public static function getAll(){
return self::$value;
}
public static function get($value){
self::$value = self::$value[$value];
return self::$value;
}
}
Here is an example for getAll method. For get method the same idea:
public function display()
{
var_dump(Form::getAll());
}
class Form
{
private static $value = array();
public static function initPost()
{
foreach($_POST as $key=>$value)
self::$value[$key] = $value;
}
public static function getAll()
{
return self::$value;
}
}
In PHP, I have a product object that contains a collection of attributes. json_encode produces this:
{"id":"123","name":"abc","attributes":{"attributes":[{"key":"sku","value":"xyz"}]}}
"attributes" listed twice is redundant. What's the best way of structuring object collections so that the json is clean?
class Product {
public $id;
public $name;
public $attributes;
public function __construct()
{
$this->attributes = new Attributes();
}
public function get($id)
{
$this->id = "123";
$this->name = "abc";
$attribute = new Attribute("sku", "xyz");
$this->attributes->add($attribute);
}
}
class Attributes
{
public $attributes;
public function __construct()
{
$this->attributes = array();
}
public function add($attribute)
{
array_push($this->attributes, $attribute);
}
}
class Attribute
{
public $key;
public $value;
public function __construct($key, $value)
{
$this->set($key, $value);
}
}
I would just use an associative array.
class Product {
...
public $attributes=array();
...
public function get($id)
{
...
$this->attributes["sku"]="xyz";
$this->attributes["foo"]="bar";
}
}
json_encode() should produce something like this:
{"id":"123","name":"abc","attributes":{"sku":"xyz","foo":"bar"}}
OR using variable variables:
class Attributes
{
public function add($key,$value)
{
$this->{$key}=$value;
}
public function drop($key)
{
unset($this->{$key});
}
}
$a=new Attributes();
$a->add('sku','xyz');
$a->add('foo','bar');
echo json_encode($a).'<br>';
$a->drop('sku');
echo json_encode($a).'<br>';
Output:
{"sku":"xyz","foo":"bar"}
{"foo":"bar"}
You can give your classes a custom json encoding format by implementing JsonSerializable.
In your case you'll just need to have Attributes implement that and give it a jsonSerialize method which returns $this->attributes.
Bellow is a PHP script.
I tried to implement the Observer pattern (without MVC structure)... only basic.
The error which is encountered has been specified in a comment.
First I tried to add User objects to the UsersLibrary repository. There was a error such as User::update() does not exists or something.
Why is that error encountered? What fix should be applied and how?
interface IObserver {
public function update(IObservable $sender);
}
interface IObservable {
public function addObserver(IObserver $obj);
public function notify();
}
class UsersLibrary implements IObservable {
private $container;
private $contor;
//private $z;
public function __construct() {//IObserver $a) {
$this->container = array();
$this->contor = 0;
echo "<div>[constructing UsersLibrary...]</div>";
$this->addObserver(new Logger());
//$this->z = $a;
}
public function add($obj) {
echo "<div>[adding a new user...]</div>";
$this->container[$this->contor] = $obj;
$this->contor++;
$this->notify();
}
public function get($index) {
return $this->container[$index];
}
public function addObserver(IObserver $obj) {
$this->container[] = $obj;
}
public function notify() {
echo "<div>[notification in progress...]</div>";
foreach($this->container as $temp) {
//echo $temp;
#################################################################
$temp->update(); //--------ERROR
//Fatal Error: Call to a member function update() on a non-object.
#################################################################
}
//$this->container[0]->update();
//$this->z->update($this);
}
}
class User {
private $id;
private $name;
public function __construct($id, $name) {
$this->id = $id;
$this->name = $name;
}
public function getId() {
return $this->id;
}
public function getName() {
return $this->name;
}
}
class Logger implements IObserver {
public function __construct() {
echo "<div>[constructing Logger...]</div>";
}
public function update(IObservable $sender) {
echo "<div>A new user has been added.</div>";
}
}
$a = new UsersLibrary(); //new Logger());
//$a->add(new User(1, "DemoUser1"));
//$a->add(new User(2, "DemoUser2"));
$a->add("Demo");
echo $a->get(0);
//echo $a->get(0)->getName();
Your User class is not implementing interface IObserver and therefore is not forced to have the method update().
You have to instantiate a new User() in order to add it to the UsersLibrary:
$library = new UsersLibrary();
$user = new User(1, "Demo");
$library->add($user);
Also, you are mixing Users and Loggers into your UsersLibrary container. Maybe think about separating the containers for them?
You are passing a string instead of an object in your $a->add() call. You should either pass in an object, or alter the code in UserLibrary::add() to wrap it's argument in an appropriate object (or do an object lookup of it sees a string, for instance find a user with that name).
$user = new User(1, "Demo");
$a = new UsersLibrary();
$a->add($user);
We have a class that holds a public array called $saved that contains lots of data required to share between methods (example below)...
class Common {
public $saved = array();
public function setUser($data) {
$this->saved['user_data'] = $data;
}
public function getUserID() {
return $this->saved['user_data']['id'];
}
}
There are literally thousands of lines of code that work like this.
The problem is that new instance of classes that extend Common are being made within some methods so when they access $saved it does not hold the same data.
The solution is to make $saved a static variable, however I can't change all of the references to $this->saved so I want to try and keep the code identical but make it act static.
Here is my attempt to make $this->saved calls static...
class PropertyTest {
private $data = array();
public function __set($name, $value) {
$this->data[$name] = $value;
}
public function __get($name) {
if (array_key_exists($name, $this->data)) {
return $this->data[$name];
}
return null;
}
public function __isset($name) {
return isset($this->data[$name]);
}
public function __unset($name) {
unset($this->data[$name]);
}
}
class Common {
public $saved;
private static $_instance;
public function __construct() {
$this->saved = self::getInstance();
}
public static function getInstance() {
if (self::$_instance === null) {
self::$_instance = new PropertyTest();
self::$_instance->foo = array();
}
return self::$_instance->foo;
}
}
This doesn't quite work when setting a variable it doesn't seem to stay static (test case below)...
class Template extends Common {
public function __construct() {
parent::__construct();
$this->saved['user_data'] = array('name' => 'bob');
$user = new User();
}
}
class User extends Common {
public function __construct() {
parent::__construct();
$this->saved['user_data']['name'] .= " rocks!";
$this->saved['user_data']['id'] = array(400, 10, 20);
}
}
$tpl = new Template();
print_r($tpl->saved['user_data']);
$this->saved is empty when User gets initialized and doesn't seem to be the same variable, the final print_r only shows an array of name => bob.
Any ideas?
First of all, I have to say that, IMO, it is not that good to use an instance's property as a class's property ($saved is not declared as static but its value is shared with all instance).
Here is a working version http://codepad.org/8hj1MOCT, and here is the commented code. Basically, the trick is located in using both ArrayAccess interface and the singleton pattern.
class Accumulator implements ArrayAccess {
private $container = array();
private static $instance = null;
private function __construct() {
}
public function getInstance() {
if( self::$instance === null ) {
self::$instance = new self();
}
return self::$instance;
}
public function offsetSet($offset, $value) {
if (is_null($offset)) {
$this->container[] = $value;
} else {
$this->container[$offset] = $value;
}
}
public function offsetExists($offset) {
return isset($this->container[$offset]);
}
public function offsetUnset($offset) {
unset($this->container[$offset]);
}
public function offsetGet($offset) {
return isset($this->container[$offset]) ? $this->container[$offset] : null;
}
}
class Common {
public $saved = null;
public function __construct() {
// initialize the "saved" object's property with the singleton
// that variable can be used with the array syntax thanks to the ArrayAccess interface
// so you won't have to modify your actual code
// but also, since it's an object, this local "$this->saved" is a reference to the singleton object
// so any change made to "$this->saved" is in reality made into the Accumulator::$instance variable
$this->saved = Accumulator::getInstance();
}
public function setUser($data) {
$this->saved['user_data'] = $data;
}
public function getUser() {
return $this->saved['user_data'];
}
}
class Template extends Common {
// you can redeclare the variable or not. Since the property is inherited, IMO you should not redeclare it, but it works in both cases
// public $saved = null;
public function __construct() {
// maybe we can move this initialization in a method in the parent class and call that method here
$this->saved = Accumulator::getInstance();
}
}
I think there are a number of issues with this implementation that could well come back to bite you. However, in your current implementation your contructing a new instance (albeit through a static call) every time.
Instead use getInstance() as your singleton hook, and make your __construct private, as you'll only be accessing it from with the context of the Common class.
Like so:
class Common {
public $saved;
private static $_instance;
private function __construct() {
}
public static function getInstance() {
if (self::$_instance === null) {
self::$_instance = new self();
... any other modifications you want to make ....
}
return self::$_instance;
}
}
And don't ever run parent::_construct(), instead always use the getInstance() method.
You might also want to ditch the idea of extending this singleton class. This is really a bad antipattern and could cost you a number of issues in the long run. Instead just maintain a Common class that other classes can read / write to. As its a singleton you don't need to worry about injection.
I seem to have solved the problem, by making $this->saved a reference to a static variable it works...
class Common {
private static $savedData = array();
public $saved;
public function __construct() {
$this->saved =& self::$savedData;
}
}