create permissions throw a QueryException in Connection.php

[lizhongqiu09]

I copy

$permission = new Permission();
$permUser = $permission->create([ 
    'name'        => 'user',
    'slug'        => [          // pass an array of permissions.
        'create'     => true,
        'view'       => true,
        'update'     => true,
        'delete'     => true,
        'view.phone' => true
    ],
    'description' => 'manage user permissions'
]);

to create permission but it no work well,thow

QueryException in Connection.php line 647:
Array to string conversion (SQL: insert into `permissions` (`name`, `slug`, `description`, `updated_at`, `created_at`) values (user, 1, manage user permissions, 2017-02-22 06:32:41, 2017-02-22 06:32:41))