从 Laravel 中预先加载的第一个表中选择特定列

Question

I have checked many solutions to get specific columns from first model with eager loading but nothing works in my case.

for example: I want specific columns from model User and want to get relationship data with eager loading without any join.

$users= User::select('name') // get one column from user table
->with(array('role_user' => function($query){
    $query->select('role_name'); // and select one column from pivot table
}))
->paginate(3);

when I don't use User::select('name) , it returns relationship data with eager load when I use select, it returns empty array.

How I can get specific columns from both tables using eager loading

Answer 1

I don't exactly know, how you defined your relationship but Laravel has some weird behavior : You should always also select the primary and foreign keys:

$users= User::select(['id', 'name']) // get one column from user table
->with(array('role_user' => function($query){
    $query->select(['id', 'role_name']); // and select one column from pivot table
}))
->paginate(3);

You can simplify it to this:

$users= User::select(['id', 'name']) // get one column from user table
->with(['role_user:id,user_id,role_name']) // and select one column from pivot table
->paginate(3);

Answer 2

We Never Know the schemas and the relationships of your project.. But I assume You This Should Work

$users = User::select('id','name') 
               ->with(['role_user:id,user_id,role_name'])
               ->paginate(3);

In your User Model Relationships must be

public function role_user(){
return $this->belongsToMany(Role::class, 'role_user'); // pivot table name
}

In your Role Model

 public function users(){
return $this->belongsToMany(User::class, 'role_user'); // pivot table name
}