Eloquent on two tables Laravel - php

Question

I have three tables:
Brand
-----------------
id | name | wheel
-----------------
Wheel
-----------------------------
id |no_of_wheel | brand_wheel
-----------------------------
Brand_Wheel
------------------------
id | brand_id | wheel_id
------------------------
I have the following models defined:
class brand
{
public function brandWheel(){
return $this->hasMany(BrandWheel::class);
}
}
class BrandWheel
{
public function brand(){
return $this->belongsTo(Brand::class);
}
}
I want to get those brands whose wheel_id is 2.
I tired:
$brands = Brand::with(['brandWheel' => function($query){
$query->where('wheel_id','=',2);
}])->get();
This code gives me all the brands I have in the table. Is there something I am missing?

Answer 1

You should use the whereHas statement. The with method will eager load the given relationships. You can find more documentation here.
$brands = Brand::with('brandWheel')->whereHas('brandWheel', function($query) {
$query->where('wheel_id', 2);
})->get();
In case you only want Brands that has a brandWheel relationship use has. Checkout documentation for more about this.

Answer 2

Your code get all brands and append to them only brandWheels where wheel_id = 2. You need to use whereHas() method.
$brands = Brand::with('brandWheel')
->whereHas('brandWheel', function($query){
$query->where('wheel_id', 2)
})
->get();

Answer 3

You need to use the Many to Many eloquent relationship described here https://laravel.com/docs/5.7/eloquent-relationships#many-to-many
So your models should look like:
class Brand
{
public function brandWheels()
{
return $this->belongsToMany(BrandWheel::class);
}
}
class BrandWheel
{
public function brands()
{
return $this->belongsToMany(Brand::class);
}
}
Notice how I have capitalized your model names since this is the naming convention as defined here https://www.php-fig.org/psr/psr-1/#3-namespace-and-class-names.
I've also made your relationship names plural, since they are many-to-many, they could return multiple results.
You can now do your query doing something along this line (not tested, might not be 100% accurate):
$brands = BrandWheel::find(2)->brands();