在Laravel 5上获得三级关系

Question

I'm trying to obtain a three level relationship data, but I'm lost about it using laravel 5.1

I'll try to explain my scenario, hope you can help me.

I've got two models called Host and User. This models are grouped by Hostgroup and Usergroup models, using a Many To Many relationship.

Then I've got a table called usergroup_hostgroup_permissions which relation an Usergroup with a Hostgroup:

+--------------+----------------------+------+-----+---------------------+----------------+
| Field        | Type                 | Null | Key | Default             | Extra          |
+--------------+----------------------+------+-----+---------------------+----------------+
| id           | int(10) unsigned     | NO   | PRI | NULL                | auto_increment |
| usergroup_id | int(10) unsigned     | NO   | MUL | NULL                |                |
| hostgroup_id | int(10) unsigned     | NO   | MUL | NULL                |                |
| action       | enum('allow','deny') | NO   |     | allow               |                |
| enabled      | tinyint(1)           | NO   |     | 1                   |                |
+--------------+----------------------+------+-----+---------------------+----------------+

I'd like to obtain a list of users that belongs to an usergroup with a relation in this table with a hostgroup where my host belongs to.

For example:

My host_1 belongs to DEV_servers. On usergroup_hostgroup_permissions table, there's an entry that allows developers to access to DEV_servers. The usergroup developer has 3 users user_1, user_2 and user_3.

Any hint? Thanks in advance!

Answer 1

In order to obtain a list of users in a particular host, you need to nest all the underlying relationships (via .) using a whereHas method on the User model. i.e.

$users = User::whereHas('usergroup.hostgroups.hosts', function($q) use ($hostID){
    $q->where('id', $hostID);
})->get();

Moreover, if you want to check against whether the user is allowed to access that particular host, then you may chain another where() to the above as such:

$users = User::whereHas('usergroup.hostgroups.hosts', function($q) use ($hostID){
    $q->where('id', $hostID)->where('usergroup_hostgroup_permissions.action', 'allow');
})->get();

Note: If you are warned on an ambiguous id field, try including the table hosts to which the id belongs to as well, i.e. hosts.id.

I am assuming that you have defined the relations for those models as follows:

class HostGroup extends Eloquent {

    /** ...
    */

    public function hosts(){
        return $this->hasMany('App\Host');
    }

    public function usergroups(){
        return $this->belongsToMany('App\UserGroup', 'usergroup_hostgroup_permissions');
    }
}

---

class Host extends Eloquent {
    /** ...
    */

    public function hostgroup() {
        return $this->belongsTo('App\HostGroup');
    }
}

---

class UserGroup extends Eloquent {
    /** ...
    */    

    public function users(){
        return $this->hasMany('App\User');
    }

    public function hostgroups(){
        return $this->belongsToMany('App\HostGroup', 'usergroup_hostgroup_permissions');
    }
}

---

class User extends Eloquent {
    /** ...
    */

    public function usergroup(){
        return $this->belongsTo('App\UserGroup');
    }
}

Hope it turns out to be helpful.