Why is the array index is undefined undefined? - php

Question

I'm having trouble finding out why is the following code not working.
I've a JSON answer from a remote server, containting the following data:
...., "UserId":{"50423":"Free Kkludkjta","54379":"Sjkllyu\u00e9lkj Nolla","67103":"Tswt\u00f3 BLLA","64469":"Uz\u00e1h G","46699":"RT\u00e1sdt UTSF","46873":"Tam\u00e1s XXXX"}, ...
(names are swapped, but since there are some special chars in the aswer I've kept those)
And I have the following code sniplet, which gives 'array index undefined for idx 64469':
$proj_schema = json_decode($proj_schema);
var_dump($proj_schema->UserId);
$avail_users = (array)$proj_schema->UserId;
var_dump($avail_users);
var_dump($avail_users[64469]);
The output is the following:
C:\wamp\www\j34\administrator\components\com_mycomponent\views\myview\view.html.php:113:
object(stdClass)[309]
public '50423' => string 'Name1' (length=14)
public '54379' => string 'Name2' (length=18)
public '67103' => string 'Name3' (length=12)
public '64469' => string 'Name4' (length=15)
public '46699' => string 'Name5' (length=11)
public '46873' => string 'Name6' (length=12)
C:\wamp\www\j34\administrator\components\com_mycomponent\views\myview\view.html.php:115:
array (size=6)
'50423' => string 'Name1' (length=14)
'54379' => string 'Name2' (length=18)
'67103' => string 'Name3' (length=12)
'64469' => string 'Name4' (length=15)
'46699' => string 'Name5' (length=11)
'46873' => string 'Name6' (length=12)
Notice: Undefined offset: 64469 in C:\wamp\www\j34\administrator\components\com_mycomponent\views\myview\view.html.php on line 116
If I walk through the array with foreach and write out the element based on 'if ($key == 64469)' it echos the name, but I cannot access the name by array key.
Results are same with PHP 5.6.32 (I know) and PHP 7.1.0. Result is the same if I put the id in "" or '';
What am I missing with the casting?

Answer 1

You are using the JSON as an object and not as an array. Therefore, the key does not exist, because it is a property.
Decode with true as 2nd argument to get an array instead of an object.
$proj_schema = json_decode($proj_schema, true);