How to fix "Cannot use object of type stdClass as array"

Fatal error: Uncaught Error: Cannot use object of type stdClass as array in /home/user/public_html/api.php:23

Common causes

• json_decode($json) without the second argument returns stdClass objects, not arrays
• Database results fetched as objects ($wpdb->get_results() default OBJECT, PDO::FETCH_OBJ, mysqli fetch_object())
• WordPress functions returning objects such as WP_Post, WP_User or WP_Term
• API client libraries returning response objects
• Mixing code written for arrays with a library that changed to returning objects

How to fix it

1. Check what the variable is. var_dump($data) or get_debug_type($data) to confirm it is an object and see its property names.
2. Use object syntax. Change $data['name'] to $data->name, and nested $data['user']['email'] to $data->user->email.
3. Decode JSON as arrays. If the rest of the code expects arrays, use json_decode($json, true) so you get associative arrays throughout.
4. Choose the fetch mode. WordPress: $wpdb->get_results($sql, ARRAY_A). PDO: $stmt->fetch(PDO::FETCH_ASSOC). mysqli: fetch_assoc() instead of fetch_object().
5. Convert only when needed. (array) $obj works for flat stdClass objects; for nested ones use json_decode(json_encode($obj), true). Avoid this on large data in hot paths.
6. For framework objects, use their API. Laravel collections support ->toArray(), ->get('key') and array access on some types; Eloquent models expose attributes via ->name or ->toArray().

PHP

$obj = json_decode($json);        // stdClass
echo $obj->user->email;

$arr = json_decode($json, true);  // array
echo $arr['user']['email'];

$rows = $wpdb->get_results($sql, ARRAY_A); // WordPress

How to stop it happening again

• Pick arrays or objects for a dataset and stick to it
• Always pass true to json_decode() when you want arrays
• Set the database fetch mode explicitly