Difficulty properly joining tables in Laravel query

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I'm having difficulty properly joining tables in L9. This joins my products and additionalProducts tables. The mission is to get all the products that can be added with productId(x). I have the Product table with all the info and additonalProduct that look like this:

id product_id additionalProductId
1 1 2
2 1 4
3 2 3
4 2 5

The meaning for product_id=1 I want to get all the info of the products with id 2 and 4 from 'product' table and for product_id=2 get the info of products 3 and 5.

This query is working when productId is hard coded('1' or '2') but when I tray make it dynamic for some reason I got error $productId undefined.

$productId = $productsInfo[0]->product_id; (when i print it with dd it show id=1 or 2). but inside the query it is undefined and I cannot understand why and how to fix it.

$viewData['additionalProducts'] = DB::table('products as p')
    ->join('addtionalproducts as ap', function ($join) {
        $join->on('p.id', '=', 'ap.additionalProductId')
             ->select('p*')
             ->where('ap.product_id', '=', $productId);
    })->get();
laravel mysql php
1 Answers

It seems you're joining the wrong columns:

$join->on('p.id', '=', 'ap.additionalProductId')

And I don't really understand this part either, because the WHERE clause doesn't belong there:

->select('p*')->where('ap.product_id', '=', $productId);

Which should rather be:

$join->on('p.additionalProductId', '=', 'ap.product_id')

And watch out for spelling errors; the question had quite few before the edit.
Better first try without the WHERE clause to get any results, then start to limit.

A join doesn't need any sub-query, that why it's actually as simple as that:

DB::table('products')
    ->leftJoin('addtionalproducts', 'products.additionalProductId', '=', 'addtionalproducts.product_id')
    ->where('products.product_id', '=', $productId);
    ->get();

https://laravel.com/docs/9.x/queries#joins

user_5493720
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