Using Query Builder to execute multiple WhereExists - laravel

Question

Here is the relevant part of the ERD:
Post is an ad of a computer or laptop.
A computer or laptop contains several parts (processor, memory, storage etc). A Postpart represents one such part.
A component is particular model of hardware, e.g. Intel Core i9 (9th gen) or Samsung 970 Evo Plus.
Since each component has their own set of attributes, we have created a polymorphic relation between processors, memories, (storage, keyboard and several other components types not shown in the diagram)
Now I need to search for all the posts that comply with the following conditions.
Have one or more of the specified words in title or description
Have got a processor with core_clock between 1.8 and 2.4 GHz.
Have got a total memory of 32 GB or more. (i.e. we need to sum up memories of each post)
In the good old SQL world, we could probably do something like:
SELECT * FROM posts p WHERE title LIKE `%Acer Aspire%` AND description LIKE `%something else%`
WHERE EXISTS
(
SELECT id FROM components c
INNER JOIN processors pr ON c.componentable_id = pr.id
INNER JOIN postparts pp ON p.id = pp.post_id
WHERE pr.core_clock BETWEEN 1.8 AND 2.4
)
AND
(
(SELECT SUM(total) FROM components c
INNER JOIN memories m ON c.componentable_id = m.id
INNER JOIN postparts pp ON p.id = pp.post_id) >= 32
)
...
and continue like that for all other components. Now I'm trying to achieve that using Eloquent or Query Builder. Here is what I have written so far:
$query = Post::where('title', 'LIKE', '%' . $searchText . '%')->
orWhere('description', 'LIKE', '%' . $searchText . '%');
$query = $query->whereExists(
function ($query) {
$query->select("1")->from('postparts')->
join('components', 'postparts.component_id', '=', 'component.id')->
join('processors', 'processors.id', '=', 'component.componentable_id')->
where('postparts.post_id', 'posts.id')->
where('processors.core_clock', '>=', 1.8)->
where('processors.core_clock', '<=', 2.4);
});
$query = $query->where(
function ($query) {
$query->join('postparts', 'postparts.post_id', '=', 'posts.id')->
join('components', 'postparts.component_id', '=', 'component.id')->
join('memories', 'memories.id', '=', 'component.componentable_id')->
sum('total') >= 32;
});
This doesn't work and complains about access violation or syntax error in the query. What am I doing wrong here?
N.B. I also have setup polymorphic relationship between the Laravel models and can successfully fetch all (polymorphic) components of a single Post using Post::with('Postparts.Component')->find($post_id). However I'm not sure if Eloquent will really be as efficient as Query Builder or a raw query. If it is, how can I filter Posts based on polymorphic child models without actually fetching them into a collection?

Answer 1

With the right relation declared being belongToMany between Post::class and Component::class, and mophTo between component and memory/processor
$posts = Post::whereHas('components', function(Builder $compQB) {
$comQB->whereHasMorph(
'componentable',
[Processor::class],
function (Builder $query) {
$query->whereBetween('core_clock', [1.8, 2.4]);
}
)
})->whereHas('components', function(Builder $compQB) {
$comQB->whereHasMorph(
'componentable',
[Memory::class],
function (Builder $query) {
$query->where('capacity', '>=', 32);
}
)
})
->where('description',....)
->where('title', .....)
->get();
I dont know how the sum memory part works, but i hope this gives you at least a good hint on the structure of the query builder.

Answer 2

I don't think you can use ->select('1') directly.
you should use raw expression:
->select(DB::raw(1))
see whereExists example.