How to to use laravel WhereIn with two tables? - php

Question

I have two tables (cards and composed_card).
The first table is the cards table, which contains multiple cards with IDs(1, 2, 3, 4, 5, 6, ....).
The second table is card_compositions, which contains three columns (composed_card and used_card).
In the second table both composed_card and used_card are foreign keys to cards table.
I'm trying to write a query in Laravel to get all cards that has at least one composed_card in card_compositions table.
I'm trying to create this query in Laravel Eloquent.
select * from `cards` where `id` in (select `composed_card` from `card_compositions` where `composed_card` = cards.id) and `cards`.`deleted_at` is null
The above SQL query works fine and returns the required results.
When I try to execute the same query in Laravel, it's not returning any results:
return Card::whereIn('id', function ($query) {
$query->select('composed_card')
->from('card_compositions')
->where('composed_card', '=', 'cards.id');
});
I wrote the above code to simulate the SQL query, but the above code is not working.
What I'm possibly doing wrong in the php code?

Answer 1

You have to use a WhereRaw. Explanation and code:
Your code is currently trying to find a match for the string 'cards.id', not join on the table cards.id. If you do
DB::enableQueryLog(); // Enable query log
\\Run your query with ->get()
dd(DB::getQueryLog());
Then you will see:
array:1 [
0 => array:3 [
"query" => "select * from `cards` where `id` in (select `composed_card` from `card_compositions` where `composed_card` = ?)"
"bindings" => array:1 [
0 => "cards.id"
]
"time" => 4.48
]
]
Note your query now has a binding, your raw query takes no parameters. Your id column is integer, and its trying to find the string "cards.id" inside it, which it never will, which explains why you get no results. So replace with:
return Card::whereIn('id', function ($query) {
$query->select('composed_card')
->from('card_compositions')
->whereRaw('composed_card = cards.id'); \\new WhereRaw clause
});
If you dump that, you will get the raw query you're expecting, and running it will get the results back.