how to make join query between three tables in laravel - laravel

Question

I want to build a query in laravel between three tables (regions, countries, packages) such that table are related together.
regions table contains (id, name, description)
countries table contains (id, region_id, name, description)
packages table contains (id, county_id, pkg_title, pkg_description, price)
I want to select all packages where region_id=1
how can I make query for this situation in laravel query builder. please help me about this question

Answer 1

Set your models as follows.
class Region extends Model
{
}
class Country extends Model
{
public function region()
{
return $this->belongsTo(Region::class);
}
}
class Package extends Model
{
public function country()
{
return $this->belongsTo(Country::class);
}
}
And state following query inside your method.
$region_id = 1;
$PackageWithRegions = Package::with([
'country' => function ($county) use ($region_id) {
return $county->with([
'region' => function ($region) use ($region_id) {
return $region->where('id', $region_id);
}
]);
}
])->get();
// $PackageWithRegions is a collection of packeges with regions where regiion_id = 1
More on eloquent relationships

Answer 2

You can use Eloquent model relationship to prform this, like below
In region controller file
$region = Region::where(['id'=>1])->with(['country'])->get(); ///fetch region with country calls relation declared in region model
In Region.php model
<?php namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Region extends Model {
protected $table = 'regions';
public function country(){
return $this->hasOne('App\Models\Country','region_id')->with(['packages']); ///this will fetch country with all pacckages on matching region_id, join of package with country is declared in country model.
}
}
In Country.php model
<?php namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Country extends Model {
protected $table = 'countries';
public function packages(){
return $this->hasMany('App\Models\Package','county_id'); //join of country with packages on county_id
}
}
In Package.php model
<?php namespace App\Models;
use Illuminate\Database\Eloquent\Model;
class Package extends Model {
protected $table = 'packages';
}

Answer 3

You can see in Laravel doc (https://laravel.com/docs/4.2/eloquent) in section Has Many Through that if you have a model like:
countries
id - integer
name - string
users
id - integer
country_id - integer
name - string
posts
id - integer
user_id - integer
title - string
Then you can access to last relation in this way:
class Country extends Eloquent {
public function posts()
{
return $this->hasManyThrough('Post', 'User');
}
}
Or using customs relations IDs:
class Country extends Eloquent {
public function posts()
{
return $this->hasManyThrough('Post', 'User', 'country_id', 'user_id');
}
}
So, you can access to the posts of a country:
$posts = Country::get(2)->posts;
// with where:
$posts = Country::where('name', '=', 'USA')->get()->posts;