laravel belongsto relationship code example

Example 1: how to use where relationship laravel

Event::with(["owner", "participants" => function($q) use($someId){
    $q->where('participants.IdUser', '=', 1);
    //$q->where('some other field', $someId);
}])

Example 2: where query from relation table in laravel

UserModel::whereHas('attachments', function ($attachmentQuery) {
    $attachmentQuery->where('level', 'profile_level');
})->get();
If you want from already queried model get specific attachments then write

$userModel->attachments()->where('level', 'profile_level')->get();

it is impossible to query both UserModel and AttachementModel in single query,
it must be at least two queries. Even fancy 
  UserModel::with('attachments')->get();, 
which returns user with all attachments, do internally two queries.

OR:

I noticed that you can define relation constraints within with method

UserModel::with(['attachments' => function ($attachmentQuery) {
    $attachmentQuery->where('level', 'profile_level');
}])->get();

Example 3: laravel belongs to

public function user()
    {
        return $this->belongsTo(User::class);
    }

Example 4: laravel belongs to

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Phone extends Model
{
    /**
     * Get the user that owns the phone.
     */
    public function user()
    {
        return $this->belongsTo('App\Models\User');
    }
}

Example 5: laravel how to query belongsTo relationship

$movies = Movie::whereHas('director', function($q) {
    $q->where('name', 'great');
})->get();

Example 6: eloquent relationships

$roles = App\User::find(1)->roles()->orderBy('name')->get();