Fetching has many relationship data Laravel and using avg function - php

Question

I am using Laravel 5 with vue js. Basically i am fetching data using axios and trying to display on the webpage using vue js v-for directive.
i have tables in database like this:
ratings Table
id review_id rating
Then i have a
reviews table
id review
They have one to many relationship between. so here in my Review Model i have method
public function ratings()
{
return $this->hasMany('App\Rating')
->selectRaw('review_id,AVG(rating) AS average_rating')
->groupBy('review_id');
}
so here i want to fetch list of reviews with their average ratings. so in my controller i am doing this:
public function getAllReviews(Request $request)
{
$reviews = Review::with('ratings')->get();
return $reviews;
}
So i am getting result but the problem is every review doesnt have ratings record so it is returning null? maybe...
when i try to render in vue template it throws an error undefined because in our collection some reviews do not have ratings.
Now my question is: Can i do something like if there is no record in the ratings for a particular review is it possible to add an array with value 0?? so in my frontend it wont see as undefined.
I hope i am successful to explain i am trying.
Thank you.

Answer 1

You may do it this way:
public function getAllReviews(Request $request)
{
$reviews = Review::selectRaw('*, IFNULL((SELECT AVG(rating) FROM ratings where ratings.review_id = reviews.id), 0) as avg_rating')->get();
return $reviews;
}

Answer 2

I would suggest using the basic relationship and a modified withCount():
public function ratings() {
return $this->hasMany('App\Rating');
}
$reviews = Review::withCount(['ratings as average_rating' => function($query) {
$query->select(DB::raw('coalesce(avg(rating),0)'));
}])->get();

Answer 3

public function showProduct($id)
{
$data = Product::where('category_id',$id)
->selectRaw('*, IFNULL((SELECT AVG(value) FROM ratings where ratings.product_id = products.id), 0) as avg_rating')
->get();
return view('ecommerce.web.productsOfcategory',compact('data'));
}

Answer 4

$avgQuery = "IFNULL((SELECT AVG(ratings.rating) FROM ratings WHERE ratings.review_id = reviews.id),'No Ratings') as avg_rating";
$reviews = Review::query()->selectRaw("reviews.*, $avgQuery")->get();
//SQL Query
$sqlQuery = "select reviews.*, IFNULL((SELECT AVG(ratings.rating) FROM ratings where ratings.review_id= ratings.id), 'No ratings') as avg_rating FROM reviews";