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Oh the treasure of a client coming to you with a site they have removed the previous dev on... treasure hunt.  Not.

Anyway, gaining access to an old site, working through the errors I came across this deprecated code

Deprecated function: array_key_exists(): Using array_key_exists() on objects is deprecated. Use isset() or property_exists() instead in common_check_language() (line 306 of /path/to/file).


What has happened and options available

array_key_exists() became deprecated in PHP 7.4.

Options recommended are isset() and property_exists().



Checks if the object or class has a property.  Note, property_exists() returns true even if the property has the value null.


Determine if a variable is declared and is different than null.  Note, isset() will return false when checking a variable that has been assigned to null. 


So how do these two options apply to the current code?  Well looking at the code:

 * @param type $obj
 * Object of the page content
 * @param type $field
 * String of a specific field
 * @return type
 * Return as an array
function common_check_language($obj, $field)
  $lookup = $obj->$field;
  $language = (array_key_exists(LANGUAGE_NONE, $obj)) ? LANGUAGE_NONE : key($obj->$field);
  return (isset($lookup[$language][0])) ? $lookup[$language][0] : $lookup[$language][1];


In this instance property_exists) better suits.  So the code now appears as

function common_check_language($obj, $field)
  $lookup = $obj->$field;
  $language = (property_exists($obj, LANGUAGE_NONE)) ? LANGUAGE_NONE : key($obj->$field);

  return (isset($lookup[$language][0])) ? $lookup[$language][0] : $lookup[$language][1];


While there are other areas to clean-up in this code, for now I'm focusing on replacing deprecated array_key_exists() with property_exists() function.

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