Laravel: Querying based on Input. If input is empty, get all - mysql

Question

I have a calendar (FullCalendar) where the user can filter down results based on a few params (Tutor Secondary Tutor, Lesson, Location). When the user makes a change to the query it hits the following code.
The issue I am having is the 'OR'. What I really want is an IF input is null then get all.
If User { Get all lessons where lead_tutor_id = 1 and secondary_tutors_id = 1 }
If User and Location { Get lessons where the user is as above, but have location_id = 3 }
etc, etc.
So, is there a way I can fall back to get ALL the results IF only one or two filters are set?
$current_events = Calendar::Where(function($query) use ($start_time, $end_time, $tutor, $location, $lesson)
{
$query->whereBetween('date_from', [$start_time, $end_time])->orderBy('date_from')
->whereRaw('lead_tutor_id = ?
OR secondary_tutors_id = ?
OR location_id = ?
OR lesson_id = ?',
[
$tutor, // Input get() for user
$tutor, // Input get() for user
$location, // Input get() for location
$lesson, // Input get() for lesson
]
);
})->with('lessons', 'leadtutor', 'secondarytutor')->get();
I've been playing with Query Scopes, but this seems to fail if passing a NULL value through to it.
Any help is very much appreciated. Thanks in advance.

Answer 1

You can build the query on forehand, store it in a variable and use it once its build.
$query = isset($var) ? $var : '';
$query .= isset($othervar) ? $othervar : '';
whereBetween(*)->orderBy(*)->whereRaw($query)
Only thing you need to keep in mind is to insert the 'OR's in the right place . So have like a check for wether it is the first thing to be inserted or not, if not then put 'OR' in front of it.
Hope that is enough info to help you.

Answer 2

After the advice from Saint Genius, I have got this working:
$built_query = [];
isset($lead_tutor) ? $built_query['lead_tutor'] = 'lead_tutor_id = ' . $lead_tutor . ' ' : null;
isset($secondary_tutor) ? $built_query['secondary_tutor'] = 'secondary_tutors_id = ' . $secondary_tutor . ' ' : null;
isset($location_id) ? $built_query['location'] = 'location_id = ' . $location_id : null;
isset($lesson_id) ? $built_query['lesson'] = 'lesson_id = ' . $lesson_id : null;
// Flatten the array so we can create a query and add the word ADD in between each element.
$built_query = implode(" AND ", $built_query);
// Run the query
$current_events = Calendar::whereBetween('date_from', [$start_time, $end_time])->orderBy('date_from')->whereRaw($built_query)->with('lessons', 'leadtutor', 'secondarytutor')->get();