I'm trying to understand this object but i can't figure out a simple fact. If count method shows public properties and the result is the number of keys in an array that was passed. In the case of an associative array when i try to access a key like a public property is not found. Maybe i misunderstood the interface.
//example
$currentDate = getdate();
//applying print_r() we can see the content
$objectDate = new ArrayObject();
//verifying the public properties- result is 11
$objectDate->count();
//but can't access keys like public properties
$objectDate->hours;
You can access array entries as properties (->) by passing the ArrayObject::ARRAY_AS_PROPS flag to the ArrayObject constructor:
//example
$currentDate = getdate();
print_r($currentDate);
// create ArrayObject from array, make entries accessible as properties (read and write).
$objectDate = new ArrayObject($currentDate, ArrayObject::ARRAY_AS_PROPS);
// verifying the public methods - result is 11
print_r($objectDate->count());
print "\n";
// accessing entries like public properties
print_r($objectDate->hours);
Such class implements ArrayAccess interface, so you can write:
$objectDate['hours']
With brackets notation, but not with arrow [->] one.
Related
When you implement the _toString method on a class, you are able to convert the object in string
$string =(string) $object
Is there an equivalent for converting in array
$array=(array) $object
From what I have tested, with this code, the attributes of the objet are transformed in index of the array, even if this object implement ArrayAccess.
I expected that casting an object with array access, I would obtain an array thith the same values I could access with the object
public class MyObject implements ArrayAccess{
private $values;
public function __construct(array $values){
$this->values=$values;
}
public function offsetSet($name,$value){
$this->values[$name]=$value;
}
//etc...
}
$myObject=new MyObject(array('foo'=>'bar');
$asArray=(array)$myObject;
print_r($asArray);
// expect array('foo'=>'bar')
// but get array('MyObjectvalues'=>array('foo'=>'bar'));
I also Notice that the native ArrayObject class has a the behavior I expected
No, there is no magic function to cast object as array.
ArrayObject is implemented with C and has weird specific behaviors.
Implement custom method asArray and use it.
Actually, it's impossible to write a general function:
/*
* #return array ArrayAccess object converted into an array
*/
function (ArrayAccess $arrayAccessObject): array { /* ... */ }
Why? Because ArrayAccess interface just gives a way to use $aa[/*argument*/] syntax, but does not give a way to iterate over all possible arguments.
We used to think that array has a finite number of keys. However ArrayAccess let us create objects having an infinite set of keys (note, the same concerns Traversable: i.e. prime numbers are "traversable").
For example, one can write a class, implementing ArrayAccess, that acts like a HTTP client with a cache (I'm not saying that it's a good idea; it's just an example). Then offsetExists($url) tells if a URL gives 200 or not, offsetGet($url) returns a content of a URL, offsetUnset($url) clears cached content, offsetSet throws a LogicException, 'cause setting a value makes no sense in this context.
// ...
if (empty($client['https://example.com/file.csv'])) {
throw new RuntimeException('Cannot download the file');
}
$content = $client['https://example.com/file.csv'];
// ...
Or maybe one wants to read/write/unset (delete) files with ArrayAccess.
Or maybe something like (set of even numbers is infinite):
$even = new EvenNumberChecker(); // EvenNumberChecker implements ArrayAccess
$even[2]; // true
$even[3]; // false
$even[5.6]; // throws UnexpectedValueException
isset($even[7.8]); // false
$even[0] = $value; // throws LogicException
ArrayAccess objects from academic examples above cannot be converted into finite arrays.
You can use json_decode and json_encode to get the most generic function for it:
public static function toArray(ArrayAccess $array): array
{
return json_decode(
json_encode($array),
true
);
}
I have the following class with several properties and a method in PHP (This is simplified code).
class Member{
public $Name;
public $Family;
public function Fetch_Name(){
for($i=0;$i<10;$i++){
$this[$i]->$Name = I find the name using RegExp and return the value to be stored here;
$this[$i]->Family = I find the family using RegExp and return the value to be stored here;
}
}//function
}//class
In the function Fetch_Name(), I want to find all the names and families that is in a text file using RegExp and store them as properties of object in the form of an array. But I don't know how should I define an array of the Member. Is it logical or I should define StdClass or 2-dimension array instead of class?
I found slightly similar discussion here, but a 2 dimensional array is used instead of storing data in the object using class properties.
I think my problem is in defining the following lines of code.
$Member = new Member();
$Member->Fetch_name();
The member that I have defined is not an array. If I do define it array, still it does not work. I did this
$Member[]= new Member();
But it gives error
Fatal error: Call to a member function Fetch_name() on a non-object in
if I give $Member[0]= new Member() then I don't know how to make $Member1 or Member[2] or so forth in the Fetch_Name function. I hope my question is not complex and illogical.
Many thanks in advance
A Member object represents one member. You're trying to overload it to represent or handle many members, which doesn't really make sense. In the end you'll want to end up with an array that holds many Member instances, not the other way around:
$members = array();
for (...) {
$members[] = new Member($name, $family);
}
Most likely you don't really need your Member class to do anything really; the extraction logic should reside outside of the Member class, perhaps in an Extractor class or something similar. From the outside, your code should likely look like this:
$parser = new TextFileParser('my_file.txt');
$members = $parser->extractMembers();
I think you should have two classes :
The first one, Fetcher (or call it as you like), with your function.
The second one, Member, with the properties Name and Family.
It is not the job of a Member to fetch in your text, that's why I would make another class.
In your function, do your job, and in the loop, do this :
for($i = 0; $i < 10; ++$i){
$member = new Member();
$member->setName($name);
$member->setFamily($family);
// The following is an example, do what you want with the generated Member
$this->members[$i] = $member;
}
The problem here is that you are not using the object of type Member as array correctly. The correct format of your code would be:
class Member{
public $Name;
public $Family;
public function Fetch_Name(){
for($i=0;$i<10;$i++){
$this->Name[$i] = 'I find the name using RegExp and return the value to be stored here';
$this->Family[$i] = 'I find the family using RegExp and return the value to be stored here';
}
}
}
First, $this->Name not $this->$Name because Name is already declared as a member variable and $this->Name[$i] is the correct syntax because $this reference to the current object, it cannot be converted to array, as itself. The array must be contained in the member variable.
L.E: I might add that You are not writing your code according to PHP naming standards. This does not affect your functionality, but it is good practice to write your code in the standard way. After all, there is a purpose of having a standard.
Here you have a guide on how to do that.
And I would write your code like this:
class Member{
public $name;
public $family;
public function fetchName(){
for($i=0;$i<10;$i++){
$this->name[$i] = 'I find the name using RegExp and return the value to be stored here';
$this->family[$i] = 'I find the family using RegExp and return the value to be stored here';
}
}
}
L.E2: Seeing what you comented above, I will modify my answer like this:
So you are saying that you have an object of which values must be stored into an array, after the call. Well, after is the key word here:
Initialize your object var:
$member = new Memeber();
$memebr->fechNames();
Initialize and array in foreach
$Member = new Member();
foreach ($Member->Name as $member_name){
$array['names'][] = $member_name;
}
foreach ($Member->Family as $member_family) {
$array['family'][] = $member_family;
}
var_dump($array);
Is this more of what you wanted?
Hope it helps!
Keep on coding!
Ares.
I've created a class that keeps some information in its attributes. It contains add() method that adds a new set of information to all of the present in this class attributes.
I'd like its objects to behave like array offsets. For example, calling:
$obj = new Class[0];
would create the object containing the first set of information.
I'd also like to use foreach() loop on that class.
The changes of attributes should be denied from outside of the class, but I should have access to them.
Is that possible?
What you need is ArrayObject it implements IteratorAggregate , Traversable , ArrayAccess , Serializable , Countable altogether
Example
echo "<pre>";
$obj = new Foo(["A","B","C"]);
foreach ( $obj as $data ) {
echo $data, PHP_EOL;
}
echo reset($obj) . end($obj), PHP_EOL; // Use array functions on object
echo count($obj), PHP_EOL; // get total element
echo $obj[1] ; // you can get element
$obj[0] = "D"; // Notice: Sorry array can not be modified
Output
A
B
C
AC
3
B
Class Used
class Foo extends ArrayObject {
public function offsetSet($offset, $value) {
trigger_error("Sorry array can not be modified");
}
}
This is how you can create multiple instance with different constructor values.
$objConfig = array(
array('id'=>1 , 'name'=>'waqar') ,
array('id'=>2 , 'name'=>'alex')
);
$objects = array();
for($i=0; $i<count($objConfig) ; $i++)
{
$objects[$i] = new ClassName($objConfig[$i]);
}
You need to implement ArrayAccess interface, examples are pretty straightforward.
Anyway I really discourage you from mixing classes and array behaviour for bad design purposes: array-wise accessing should be used just to keep syntax more concise.
Take full advantage of classes, magic methods, reflection: there's a bright and happy world out there, beyond associative arrays.
In this case, why do you not just have an array of your class instances? A very simple example:
/**
* #var MyClass[]
*/
$myClasses = array();
$myClasses[] = new myClass();
Or alternatively use one of the more specialised SPL classes, here: http://php.net/manual/en/book.spl.php, such as SplObjectStorage (I haven't had a need for this, but it looks like it might be what you need)
Finally, you could roll your own, by simply creating a class that extends ArrayAccess and enforces you class type?
It really depends on what you need, for the vast majority of cases I would rely on storing classes in an array and enforcing any business logic in my model (so that array values are always the same class). This may be less performant, but assuming you're making a web app it is highly unlikely to be an issue.
Is it possible to check properties from a PHP stdClass? I have some models which are being generated as an stdClass. When using them I would like to check if the properties I'm calling exist in some kind of Core-class. I've noticed __get is ignored by the stdClass...
How can properties from a stdClass be checked if they exist in the object?
StdClass objects contain only porperties, not code. So you can't code anything from "within" them. So you need to work around this "shortcomming". Depending on what generates these classes this can be done by "overloading" the data (e.g. with a Decorator) providing the functionality you've looking for:
class MyClass
{
private $subject;
public function __construct(object $stdClass)
{
$this->subject = $stdClass;
}
public function __get($name)
{
$exists = isset($this->subject->$name);
#...
}
}
$myModel = new MyClass($model);
Use get_object_vars() to iterate through the stdClass object, then use the property_exists() function to see if the current property exists in the parent class.
Just cast it to an array
$x = (array) $myStdClassObject;
Then you can use all the common array functions
Problem: I am trying to extend PHP's ArrayObject as shown below. Unfortunately I can't get it to work properly when setting multi-dimensional objects and instead an error thrown as I have the strict settings enabled in PHP. (Error: Strict standards: Creating default object from empty value)
Question: How can I modify my class to automatically create non-existing levels for me?
The code:
$config = new Config;
$config->lvl1_0 = true; // Works
$config->lvl1_1->lvl2 = true; // Throws error as "lvl1" isn't set already
class Config extends ArrayObject
{
function __construct() {
parent::__construct(array(), self::ARRAY_AS_PROPS);
}
public function offsetSet($k, $v) {
$v = is_array($v) ? new self($v) : $v;
return parent::offsetSet($k, $v);
}
}
Taking a more oop view of your issue, you can create a class that models the concept of an multi-dimensional object.
The solution im posting doesn't extends from ArrayObject to achieve the goals you mention. As you tagged your question as oop, i think it´s important to reinforce the separation the way you store an object's state from how do you access it.
Hope this will help you achieve what you need!
From what you said, an multi-dimensional object is one that:
handles multiple levels of nested information
it does so by providing reading/writing access to the information via properties
behaves nicely when undefined properties are accessed. This means that, for example, you do the following on an empty instance: $config->database->host = 'localhost' the database and host levels are initialized automatically, and host will return 'localhost' when queried.
ideally, would be initialized from an associative arrays (because you can already parse config files into them)
Proposed Solution
So, how can those features be implemented?
The second one is easy: using PHP's __get and __set methods. Those will get called whenever an read/write is beign done on an inaccessible property (one that's not defined in an object).
The trick will be then not to declare any property and handle propertie's operations through those methods and map the property name being accessed as a key to an associative array used as storage. They'll provide basically an interface for accessing information stored internally.
For the third one, we need a way to create a new nesting level when a undeclared property is read.
The key point here is realizing that the returned value for the property must be an multi-dimensional object so further levels of nesting can be created from it also: whenever we´re asked for a property whose name is not present in the internal array, we´ll associate that name with a new instance of MultiDimensionalObject and return it. The returned object will be able to handle defined or undefined properties too.
When an undeclared property is written, all we have to do is assign it's name with the value provided in the internal array.
The fourth one is easy (see it on __construct implementation). We just have to make sure that we create an MultiDimensionalObject when a property's value is an array.
Finally, the fist one: the way we handle the second and third features allows us to read and write properties (declared and undeclared) in any level of nesting.
You can do things like $config->foo->bar->baz = 'hello' on an empty instance and then query for $config->foo->bar->baz successfully.
Important
Notice that MultiDimensionalObject instead of beign itself an array is it composed with an array, letting you change the way you store the object's state as needed.
Implementation
/* Provides an easy to use interface for reading/writing associative array based information */
/* by exposing properties that represents each key of the array */
class MultiDimensionalObject {
/* Keeps the state of each property */
private $properties;
/* Creates a new MultiDimensionalObject instance initialized with $properties */
public function __construct($properties = array()) {
$this->properties = array();
$this->populate($properties);
}
/* Creates properties for this instance whose names/contents are defined by the keys/values in the $properties associative array */
private function populate($properties) {
foreach($properties as $name => $value) {
$this->create_property($name, $value);
}
}
/* Creates a new property or overrides an existing one using $name as property name and $value as its value */
private function create_property($name, $value) {
$this->properties[$name] = is_array($value) ? $this->create_complex_property($value)
: $this->create_simple_property($value);
}
/* Creates a new complex property. Complex properties are created from arrays and are represented by instances of MultiDimensionalObject */
private function create_complex_property($value = array()){
return new MultiDimensionalObject($value);
}
/* Creates a simple property. Simple properties are the ones that are not arrays: they can be strings, bools, objects, etc. */
private function create_simple_property($value) {
return $value;
}
/* Gets the value of the property named $name */
/* If $name does not exists, it is initilialized with an empty instance of MultiDimensionalObject before returning it */
/* By using this technique, we can initialize nested properties even if the path to them don't exist */
/* I.e.: $config->foo
- property doesn't exists, it is initialized to an instance of MultiDimensionalObject and returned
$config->foo->bar = "hello";
- as explained before, doesn't exists, it is initialized to an instance of MultiDimensionalObject and returned.
- when set to "hello"; bar becomes a string (it is no longer an MultiDimensionalObject instance) */
public function __get($name) {
$this->create_property_if_not_exists($name);
return $this->properties[$name];
}
private function create_property_if_not_exists($name) {
if (array_key_exists($name, $this->properties)) return;
$this->create_property($name, array());
}
public function __set($name, $value) {
$this->create_property($name, $value);
}
}
Demo
Code:
var_dump(new MultiDimensionalObject());
Result:
object(MultiDimensionalObject)[1]
private 'properties' =>
array
empty
Code:
$data = array( 'database' => array ( 'host' => 'localhost' ) );
$config = new MultiDimensionalObject($data);
var_dump($config->database);
Result:
object(MultiDimensionalObject)[2]
private 'properties' =>
array
'host' => string 'localhost' (length=9)
Code:
$config->database->credentials->username = "admin";
$config->database->credentials->password = "pass";
var_dump($config->database->credentials);
Result:
object(MultiDimensionalObject)[3]
private 'properties' =>
array
'username' => string 'admin' (length=5)
'password' => string 'pass' (length=4)
Code:
$config->database->credentials->username;
Result:
admin
Implement the offsetGet method. If you are accessing a non exist property, you can create one as you like.
As you are extend ArrayObject, you should use the array way [] to set or get.
Copied pasted your code and it works fine on my PHP test box (running PHP 5.3.6). It does mention the Strict Standards warning, but it still works as expected. Here's the output from print_r:
Config Object
(
[storage:ArrayObject:private] => Array
(
[lvl1_0] => 1
[lvl1_1] => stdClass Object
(
[lvl2] => 1
)
)
)
It is worth noting that on the PHP docs there is a comment with guidance related to what you're trying to do:
sfinktah at php dot spamtrak dot org 17-Apr-2011 07:27
If you plan to derive your own class from ArrayObject, and wish to maintain complete ArrayObject functionality (such as being able to cast to an array), it is necessary to use ArrayObject's own private property "storage".
Detailed explanation is linked above but, in addition to offsetSet which you have and offsetGet which xdazz mentions, you also must implement offsetExists and offsetUnset. This shouldn't have anything to do with your current error but it is something you should be mindful of.
Update: xdazz' second-half has the answer to your problem. If you access your Config object as an array, it works without any errors:
$config = new Config;
$config[ 'lvl1_0' ] = true;
$config[ 'lvl1_1' ][ 'lvl2' ] = true;
Can you do that or are you restricted to the Object syntax for some reason?