Laravel 5.3 - Pull data of polymorphic table in one query? - php

Question

Using the polymorphic relationship likeable, I have setup authors and books as likeable_type in likeable_items table.
Here are the models:
class Like extends Model {
public function likeable(){
return $this->morphTo();
}
}
class Author extends Model {
public function likes(){
return $this->morphMany('App\Like', 'likeable');
}
}
class Book extends Model {
public function likes(){
return $this->morphMany('App\Like', 'likeable');
}
}
I want to use one efficient query to pull them both in with their respective data, paginated by 10, something like this does not work (I commented the code to show what is needed in each step).
$likeableData =
DB::table('likeable_items')
// We want to fetch additional data depending on likeable_type
->select(['books.title', 'books.author_name', 'book_counts.like_count']) // when likeable_type = 'book'
->select(['authors.name', 'authors.country', 'authors.age', 'author_counts.like_count']) // when likeable_type = 'author'
->leftJoin('books', 'books.id', '=', 'likeable_items.likeable_id') // when likeable_type = 'book'
->leftJoin('book_counts', 'book_counts.book_id', '=', 'likeable_items.likeable_id') // when likeable_type = 'book'
->leftJoin('author_counts', 'author_counts.author_id', '=', 'likeable_items.likeable_id') // when likeable_type = 'author'
// We want to have distinct results, based on unique id of book/author
->distinct()
// We want to order by the highest like_count, regardlress of likeable_type
->orderBy('book_counts.like_count', 'desc') // order by highest like_count when likeable_type = 'book'
->orderBy('author_counts.like_count', 'desc') // order by highest like_count when likeable_type = 'author_counts'
// We want to paginate the mixed results
->paginate(10);
return $likeableData;
How can I get the mixed results back of the highest liked author/book by likes_count, with their respective data, paginated by 10?
UPDATE:
Here is the table schema:
Table: likeable_items
- id
- likeable_id (book_id or author_id)
- likeable_type (book or author)
Table: books
- id
- title
- author_name
Table: book_counts
- book_id
- like_count
Table: authors
- id
- name
- country
- age
Table: author_counts
- author_id
- like_count

Answer 1

You could do it from your Like model without the need for the counts tables with some sub selects and grouping like:
$likes = Like::select('*')
->selectSub('COUNT(*)', 'total_likes')
->with('likeable')
->whereIn('likeable_type', [Book::class, Author::class])
->groupBy('likeable_type', 'likeable_id')
->orderBy('total_likes', 'desc')
->paginate(10);
Then to access the values:
foreach($likes as $likedItem) {
$likedItem->total_likes;
if($likedItem->likeable_type === Book::class) {
// Your book logic here
$likedItem->likeable->title;
$likedItem->likeable->author_name;
} else {
// Your author logic here
$likedItem->likeable->name;
$likedItem->likeable->country;
$likedItem->likeable->age;
}
}

Answer 2

If you are willing to change the schema and have more than one query a possible solution would be:
Update Schema:
Table: likeable_items
- id
- likeable_id (book_id or author_id)
- likeable_type (book or author)
- like_count
Table: books
- id
- title
- author_name
Table: authors
- id
- name
- country
- age
Update Model:
class Like extends Model
{
/**
* #return bool
*/
public function isBook()
{
return ($this->likeable_type === Book::class);
}
/**
* #return bool
*/
public function isAuthor()
{
return ($this->likeable_type === Author::class);
}
}
Except you need book_counts and author_counts for a special piece of logic on your system, I would just remove them and move like_count to likeable_items.
like_count is a property common to books and authors so I think that it's reasonable to place it on likeable_items.
Querires:
$likes = Like::orderBy('like_count', 'desc')
->paginate(10);
$likeable_id = $likes->pluck('likeable_id');
$books = Book::whereIn('id', $likeable_id)->get()->groupBy('id');
$authors = Author::whereIn('id', $likeable_id)->get()->groupBy('id');
So, at this point get the best 10 is trivial.
To fetch the data instead we use pluck and then groupBy with whereIn.
About this point, please consider that if you are using likeable_items to dispatch the id for books and authors the two whereIn will return just the data you need.
Instead, if you use likeable_items just to cache books and authors ids, you will potentially have some data you don't need.
How to display the content:
#forelse ($likes as $item)
#if ($item->isBook())
$books[$item->likeable_id][0]->title;
$books[$item->likeable_id][0]->author_name;
#else
$authors[$item->likeable_id][0]->name;
$authors[$item->likeable_id][0]->country;
$authors[$item->likeable_id][0]->age;
#endif
#empty
#endforelse
Final Considerations:
Using this approach you will:
- change your schema and update your model
- you won't use morphTo,
- you do 3 queries instead of 1 but are not complex
- you can directly use paginate
- you always use id for the secondary queries (which is good for performance)
The only "dark side" as I said is that you may have some content you don't need in $books and $authors in case you are not dispatching the ids from likeable_items but I think is a reasonable trade-off.