Laravel Eloquent HasManyThrough returning empty array

Question

I am having trouble getting a query from HasManyThrough relation in Eloquent.

These are my tables

PAGES

• id
• columns
• slideshow_fk

SLIDESHOWS

• id
• columns

SLIDES

• id
• columns
• slideshow_id

My Page model:

class Page extends Model
{
    public function slideshow_id(){
        return $this->belongsTo(Slideshow::class);
    }
    public function slides(){
        return $this->hasManyThrough('App\Slide','App\Slideshow','id','slideshow_id','slideshow_fk');
    }
}

Controller

$page=Page::where("slug","=",$slug)->with('slides')->first();

Query log: I am not Page ID:3 with slideshow_fk:1, [? = 1]

select `slides`.*, `slideshows`.`id` from `slides` inner join `slideshows` on `slideshows`.`id` = `slides`.`slideshow_id` where `slideshows`.`id` in (?)

page->slides array:

[]

PhpMyAdmin SQL copy/paste:

http://prntscr.com/e0hy4e

Which are the correct 3 slides I need for my page.

Why do I get an empty array ?

Answer 1

You cannot you hasManyThrough() here as your implementation doesn't support the need for one.

Say you have three models A , B and C and A want to connect to C via B .

Then if you want to use hasManyThrough()

• B needs to have A 's primary key as a foreign key
• C needs to have B 's primary key as a foreign key

That is A <- B <- C

If I put this to your example, what you have is

• A have B 's primary key as a foreign key
• C have B 's primary key as a foreign key

Which is A -> B <- C .

What you can do here is define models like this.

class Pages extends Model
{
    public function slideshow()
    {
        return $this->belongsTo(Slideshow::class);
    }
}

class Slideshow extends Model
{
    public function slides()
    {
        return $this->hasMany(Slides::class);
    }

}

class Slides extends Model
{

}

And query like

$pags = Pages::with('slideshow.slides')->where('slug', $slug)->first();

I suggest using proper naming conventions.