Laravel eloquent query not working with sub query - php

Question

so we have a page where we have to filter a list of students based on filters selected by the user in the front end.
Filters in the front end
Filter by Subjects (students who have opted for subjects)
Filter by location (students who are part of a location)
Filter by Gender (self explanatory)
Now Location & Gender are part of student table, so it is very easy to use these filters with simple query but subjects is a totally different table
Check the attached table
Query current we have
$student = Student::select('*')
->where(function ($query) use ($request) {
if (!empty($request->location)) {
$query->whereIn('location', $request->location);
} else if (!empty($request->gender)) {
$query->where('gender', $request->gender);
} else if (!empty($request->subjects)) {
// selecting students by id who enrolled for a particular subject
// end user can select multiple subjects
$query->whereIn('id', function($subjectQuery) use ($request) {
$subjectQuery->select('student_id')
->whereIn('subject_id', [$request->subjects])
->from('student_subjects')
->get();
});
})->get();
when passing {"subject": [201, 205]}
getting following error
Nested arrays may not be passed to whereIn method
But when passing {"subject": [201]}
This return empty result,
What are we doing wrong? or what we can do to improve this query?

Answer 1

In this case I usually use when() and whereHas() (assuming you have model StudentSubject and have the relationship). It will look like this:
$student = Student::select('*')
->when(!empty($request->location), function ($query) use($request) {
$query->whereIn('location', $request->location);
})
->when(!empty($request->gender), function ($query) use($request) {
$query->whereIn('gender', $request->gender);
})
->when(!empty($request->subjects), function ($query) use($request){
$query->whereHas('StudentSubject',function($sub) use($request) {
return $sub->whereIn('subject_id',$request->subjects);
});
})
->get();
I don't know your $request->subjects format so I assuming it's just the usual array like [1,2,3].