Laravel Eloquent Eager Loading : Join same table twice

问题

I have a users table and an appointments table. In appointment table I have two user ID's (customer_id, staff_id). I want to retrieve all the appointments with customer name and the staff name.

users table
id
name

appointments table
id
staff_id(user_id)
customer_id(user_id)
datetime

As you can see, I have to join the users table twice with the appointments table. Usually I do this with inner joins.

Can we do the same thing with Laravel eloquent eager loading using with()?

Can we do something like:

appointments::with('users' * )->get();?
* Do something here to inner join users table twice, and read user1.name as staff_name,   user2.name as customer_name.

This is the final output I need:

appointment_id
staff_id
staff_name
customer_id
customer_name
datetime

I have another question, what is the second parameter in the following query?

User::with(array(
    'post'=> function() use $region {
          //what is use $region means? Can you give me an example?
     }
));

Thanks!

回答1:

class T1 extends Eloquent {

    protected $table = 't1';


}

class T2 extends Eloquent {

    protected $table = 't2';

    public function customer()
    {
        return $this->belongsTo('T1','c_id');//c_id - customer id
    }
    public function staff()
    {
        return $this->belongsTo('T1','s_id');//s_id - staff id
    }
}

1) With use "with":

    $list = \T2::with('customer')->with('staff')->get();
    foreach ($list as $row) {
        echo 'ID: '.$row->id.', customer: '.$row->customer->name.', staff: '.$row->staff->name.'<br>';
    }

2) With joins:

$list = \T2::leftJoin('t1 as customer_table', 'customer_table.id','=','t2.c_id')
        ->leftJoin('t1 as staff_table', 'staff_table.id','=','t2.s_id')
        ->select('staff_table.name as staff_name','customer_table.name as customer_name')
        ->get();
foreach ($list as $row) {
    echo 'customer: '.$row->customer_name.', staff: '.$row->staff_name.'<br>';
}

About second question - This is for subqueries. Look documentation: http://laravel.com/docs/eloquent#eager-loading

来源：https://stackoverflow.com/questions/21834379/laravel-eloquent-eager-loading-join-same-table-twice

标签

php

database

join

laravel

eloquent