How to get data values from collection using group by on laravel eloquent?

To get data values from a collection using group by on Laravel Eloquent, you can use the groupBy() method followed by the pluck() method. Here's a step-by-step guide on how to do it:

Define the relationship between your models, if necessary. For example, if you have two models Post and Comment, and a Post has many Comments, you can define the relationship in Post model as follows:

public function comments()
{
    return $this->hasMany(Comment::class);
}

Use Eloquent query builder to get the data you need with group by. For example, if you want to get the total number of comments for each post, you can do:

$query = Post::withCount('comments');
$results = $query->get();

If you want to get specific data from the related model, you can use the pluck() method to get a collection of the data. For example, if you want to get the average comment length for each post, you can do:

$query = Post::with(['comments' => function ($query) {
    $query->select(DB::raw('AVG(LENGTH(comments.content) + LENGTH(comments.content) / 2) as avg_length'));
}]);
$results = $query->groupBy('posts.id')->get();

$data = $results->map(function ($item) {
    return [
        'post_id' => $item->id,
        'avg_comment_length' => $item->comments->avg('avg_length')
    ];
});

In the above example, we are using the with() method to eager load the related comments model, and then we are using a closure to select the average length of the comments for each post. We are also using the pluck() method to get a collection of the avg_length data from the related comments model for each post. Finally, we are using the map() method to transform the results into an array with the desired keys.

The $data variable will now be an array of results with the keys post_id and avg_comment_length.