Laravel Eloquent Eager Loading：加入同一张表两次
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Laravel Eloquent Eager Loading : Join same table twice
提问by The Dude
I have a userstable and an appointmentstable. 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.
我有一个用户表和一个约会表。在约会表中，我有两个用户 ID（customer_id、staff_id）。我想检索所有带有客户姓名和员工姓名的约会。
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.
如您所见，我必须将 users 表与约会表连接两次。通常我用内部连接来做这件事。
Can we do the same thing with Laravel eloquent eager loading using with()?
我们可以使用 with() 对 Laravel 雄辩的预加载做同样的事情吗？
Can we do something like:
我们可以做这样的事情：
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:
这是我需要的最终输出：
appointment_id
staff_id
staff_name
customer_id
customer_name
datetime
I have another question, what is the second parameter in the following query?
我还有一个问题，以下查询中的第二个参数是什么？
User::with(array(
'post'=> function() use $region {
//what is use $region means? Can you give me an example?
}
));
Thanks!
谢谢！
回答by Nostalgie
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":
1) 使用“与”：
$list = \T2::with('customer')->with('staff')->get();
foreach ($list as $row) {
echo 'ID: '.$row->id.', customer: '.$row->customer->name.', staff: '.$row->staff->name.'<br>';
}
2) With joins:
2) 使用连接：
$list = \T2::leftJoin('t1 as customer_table', 'customer_table.id','=','t2.c_id')
->leftJoin('t1 as staff_table', 'staff_table.id','=','t2.s_id')
->select('staff_table.name as staff_name','customer_table.name as customer_name')
->get();
foreach ($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
关于第二个问题 - 这是针对子查询的。查看文档：http: //laravel.com/docs/eloquent#eager-loading
