Eloquent: Composite WhereIn condition - php

Question

Is there a clean way to do a composite WHERE ... IN () condition with Eloquent/laravel.
The query result would be :
SELECT * FROM `table` WHERE (relation_type, relation_id) IN (('App\\Model', 1),('App\\Model', 3))
As you can see, that would be helpful for a single query fetch of an entity with polymorphic relation linked to 5 other models.
My current solution would be pure MySQL:
//Example :array of array with Model name & id
$couples = [
['relation_type' => 'App\\Model', 'relation_id' => 1],
['relation_type' => 'App\\ModelTwo', 'relation_id' => 2],
['relation_type' => 'App\\ModelThree', 'relation_id' => 5],
['relation_type' => 'App\\ModelTwo', 'relation_id' => 20],
//...
['relation_type' => 'App\\Model', 'relation_id' => 999],
];
$query = "SELECT * FROM table WHERE ('relation_type', 'relation_id') IN (("
.implode('),(', array_map(function ($entry) {
return "'".$entry['relation_type']."',".$entry['relation_id']; //I know , in relation_type the '\' needs to be escaped.
}, $couples))
."))";
$results = \DB::select($query);
}

Answer 1

Firstly you are able to put in DB::raw in both column and value, this will solve the problem of getting the SQL query correct, i tested the following on MySql 5.7 and it works. Db::raw just adds raw strings to the query, can be dangerous with injections.
->whereIn(DB::raw('(relation_type, relation_id)'), [DB::raw("('App\\Model', '2')")])
Now we just need to convert your array into that structure, my approach was a array_map foreach can also do the trick.
$couples = array_map(function ($item) {
$type = $item['relation_type'];
$id = $item['relation_id'];
return DB::raw("('$type', '$id')");
}, $couples);
Then call it with a simple Laravel query and you should be good to go.
$models = Model::whereIn(DB::raw('(relation_type, relation_id)'), $couples)->get()