Hello,

Searching without a relation to your model sounds for me a little bit strange to implement. (Unless you have some validation in your request) Now it is possible to add a search on a not existing column to your query. That will result in an error.

But your question about searching on your relation. You can use the whereHas functions ( see: https://laravel.com/docs/9.x/eloquent-relationships#querying-relationship-existence )

It is possible to search the existing of a relation with $builder->has('relation'); or you can search on the existing of a relation with a specific value.

$builder->whereHas('relation', static function (Builder $relationQuery) use ($value) {
    $relationQuery->where('column_on_the_relation',  'LIKE', '%'. strtolower($value) . '%');
});

Small note: I have updated your post to make the code more readable

Hello tvbeek,

Thank you for your reply.

$builder->whereHas('relation', static function (Builder $relationQuery) use ($value) {
    $relationQuery->where('column_on_the_relation',  'LIKE', '%'. strtolower($value) . '%');
});

that was the right keyword for my problem

EDIT: But now I have the problem, if I want to filter by semester, for example, I get the following error Call to undefined method App\Models\Document::semester().

my code is as follows

if($builder->whereHas($column)) {
    $builder->whereHas($column, static function (Builder $relationQuery) use ($column, $value) {
        $relationQuery->where($column,  'LIKE', '%'. strtolower($value) . '%');
    });
} else {
    array_push($where, [$column, 'LIKE', Str::lower("%{$value}%")]);
}