Запись данных в json php

                    elseif ($body[0] == '/баланс'){
                    $json = file_get_contents('users.json');
                    $UserData = json_decode($json, true);
                    $new_user = [
                        'id' => $this->from_id,
                        'balance' => 1500
                        ];
                    if($UserData['id'] != $this->from_id) {
                        file_put_contents('users.json', json_encode($new_user).PHP_EOL, FILE_APPEND);
                    }
                    $self = ($this->random(['