How to access object properties with names like integers or invalid property names?
PhpObjectPropertiesPhp Problem Overview
I am using json_decode() something like:
$myVar = json_decode($data)
Which gives me output like this:
[highlighting] => stdClass Object
(
[448364] => stdClass Object
(
[Data] => Array
(
[0] => Tax amount liability is .......
I want to access the string value in the key [0]. When I try to do something like:
print $myVar->highlighting->448364->Data->0;
I get this error:
> Parse error: syntax error, unexpected T_DNUMBER
The two numerals/integers there seems to be problem.
Php Solutions
Solution 1 - Php
Updated for PHP 7.2
PHP 7.2 introduced a behavioral change to converting numeric keys in object and array casts, which fixes this particular inconsistency and makes all the following examples behave as expected.
One less thing to be confused about!
Original answer (applies to versions earlier than 7.2.0)
PHP has its share of dark alleys that you really don't want to find yourself inside. Object properties with names that are numbers is one of them...
What they never told you
Fact #1: You cannot access properties with names that are not legal variable names easily
$a = array('123' => '123', '123foo' => '123foo');
$o = (object)$a;
echo $o->123foo; // error
Fact #2: You can access such properties with curly brace syntax
$a = array('123' => '123', '123foo' => '123foo');
$o = (object)$a;
echo $o->{'123foo'}; // OK!
Fact #3: But not if the property name is all digits!
$a = array('123' => '123', '123foo' => '123foo');
$o = (object)$a;
echo $o->{'123foo'}; // OK!
echo $o->{'123'}; // error!
Fact #4: Well, unless the object didn't come from an array in the first place.
$a = array('123' => '123');
$o1 = (object)$a;
$o2 = new stdClass;
$o2->{'123'} = '123'; // setting property is OK
echo $o1->{'123'}; // error!
echo $o2->{'123'}; // works... WTF?
Pretty intuitive, don't you agree?
What you can do
Option #1: do it manually
The most practical approach is simply to cast the object you are interested in back into an array, which will allow you to access the properties:
$a = array('123' => '123', '123foo' => '123foo');
$o = (object)$a;
$a = (array)$o;
echo $o->{'123'}; // error!
echo $a['123']; // OK!
Unfortunately, this does not work recursively. So in your case you 'd need to do something like:
$highlighting = (array)$myVar->highlighting;
$data = (array)$highlighting['448364']->Data;
$value = $data['0']; // at last!
Option #2: the nuclear option
An alternative approach would be to write a function that converts objects to arrays recursively:
function recursive_cast_to_array($o) {
$a = (array)$o;
foreach ($a as &$value) {
if (is_object($value)) {
$value = recursive_cast_to_array($value);
}
}
return $a;
}
$arr = recursive_cast_to_array($myVar);
$value = $arr['highlighting']['448364']['Data']['0'];
However, I 'm not convinced that this is a better option across the board because it will needlessly cast to arrays all of the properties that you are not interested in as well as those you are.
Option #3: playing it clever
An alternative of the previous option is to use the built-in JSON functions:
$arr = json_decode(json_encode($myVar), true);
$value = $arr['highlighting']['448364']['Data']['0'];
The JSON functions helpfully perform a recursive conversion to array without the need to define any external functions. However desirable this looks, it has the "nuke" disadvantage of option #2 and additionally the disadvantage that if there is any strings inside your object, those strings must be encoded in UTF-8 (this is a requirement of json_encode).
Solution 2 - Php
Just wanted to add to Jon's eloquent explanation the reason why this fails. It's all because when creating an array, php converts keys to integers — if it can — which causes lookup problems on arrays which have been cast to objects, simply because the numeric key is preserved. This is problematic because all property access options expect or convert to strings. You can confirm this by doing the following:
$arr = array('123' => 'abc');
$obj = (object) $arr;
$obj->{'123'} = 'abc';
print_r( $obj );
Which would output:
stdClass Object (
[123] => 'abc',
[123] => 'abc'
)
So the object has two property keys, one numeric (which can't be accessed) and one string based. This is the reason why Jon's #Fact 4 works, because by setting the property using curly braces means you always define a string-based key, rather than numeric.
Taking Jon's solution, but turning it on its head, you can generate an object from your array that always has string-based keys by doing the following:
$obj = json_decode(json_encode($arr));
From now on you can use either of the following because access in this manner always converts the value inside the curly brace to a string:
$obj->{123};
$obj->{'123'};
Good old illogical PHP...
Solution 3 - Php
>For PHP 7
Accessing Object properties having numbers as property name. Mostly needed after casting array to object.
$arr = [2,3,7];
$o = (object) $arr;
$t = "1";
$t2 = 1;
$t3 = (1);
echo $o->{1}; // 3
echo $o->{'1'}; // 3
echo $o->$t; // 3
echo $o->$t2; // 3
echo $o->$t3; // 3
echo $o->1; // error
echo $o->(1); // error
Solution 4 - Php
I had copied this function from the net. If it works as it says ("Function to Convert stdClass Objects to Multidimensional Arrays"), try the following:
<?php
function objectToArray($d) {
if (is_object($d)) {
// Gets the properties of the given object
// with get_object_vars function
$d = get_object_vars($d);
}
if (is_array($d)) {
/*
* Return array converted to object
* Using __FUNCTION__ (Magic constant)
* for recursive call
*/
return array_map(__FUNCTION__, $d);
}
else {
// Return array
return $d;
}
}
?>
- first pass your array to
objectToArrayfunction - then take the return value
- echo
[highlighting][448364][Data][0]
Solution 5 - Php
If an object begins with @ like:
SimpleXMLElement Object (
[@attributes] => Array (
[href] => qwertyuiop.html
[id] => html21
[media-type] => application/xhtml+xml
)
)
You have to use:
print_r($parent_object->attributes());
because $parent_object->{'@attributes'} or $parent_object['@attributes'] won't work.
Solution 6 - Php
A final alternative to Jon's comprehensive answer:
Simply use json_decode() with the second parameter set to true.
$array = json_decode($url, true);
This then returns an associative array rather than an object so no need to convert after the fact.
This may not be suitable to every application but it really helped me to easily reference a property of the oroginal object.
Solution was found in this tutorial - http://nitschinger.at/Handling-JSON-like-a-boss-in-PHP/
Regards
Solution 7 - Php
I'm afraid you aren't allowed to name objects starting with numerics. Rename the first one "448364" starting with a letter.
The second one is an array, those are to be accessed by brackets like so:
print myVar->highlighting->test_448364->Data[0]
instead