How to solve undefined variable - php

Question

view page:
#if(count($applications)>0)
<table class= "table table-striped">
<tr>
<th>Email</th>
<th>Date Applied</th>
<th>Leave Type</th>
<th>Leave Status</th>
<th></th>
</tr>
#foreach($applications as $application )
<tr>
<td>{{$application ->user->email}}</td>
<td>{{$application ->dateApplied}}</td>
<td>{{$application ->leaveType}}</td>
<td>{{$application ->leaveStatus}}</td>
<td>
{!!Form::open(['action'=>['ApplicationAdminController#destroy', $application ->appId], 'method'=>'DELETE'])!!}
{{Form::hidden('_method', 'DELETE')}}
{{Form::submit('Delete', ['class' => 'btn btn-danger'])}}
{!!Form::close()!!}
</td>
</tr>
#endforeach
</table>
controller:
public function destroy($appId)
{
$application = Application::find( $appId);
$application ->delete();
$this->deleteLeave($appId);
return redirect('/applicationAdminHistory')->with ('success', 'Application Removed');
}
public function deleteLeave($appId){
$user_id = Auth::id();
$req = DB::table('leave_summaries')
->where('user_id',$user_id)
->increment($leaveType,$day);
}
What I want to do is when click delete button the application will deleted and will do increments at the leave_summaries table. The increment at the leave_summaries based on the value of day and leave type in the application that has been deleted. After i run this code i got undefined variable error as shown below:

Answer 1

In this Code Please Pass $user_id , $leaveType ,$day:
public function deleteLeave($appId){
$req = DB::table('leave_summaries')
->where('user_id',$user_id)
->increment($leaveType,$day);
}

Answer 2

You didn't defined these three variables : $user_id, $leaveType, $day
You need to pass these values as parameters into the deleteLeave() method or these values had to be defined before the method called.
public function deleteLeave($user_id, $leaveType, $day){
$req = DB::table('leave_summaries')
->where('user_id',$user_id)
->increment($leaveType, $day);
}