Laravel example code with wherehas

wherehas-example.php

<?php
/*
*  example code gist,  
*/

Model_A::whereHas('Model_B',
  function (\Illuminate\Database\Eloquent\Builder $builder) {
            $builder->upcoming()->where('cancel_reason', Model_B::REASON_NOT_AVAILABLE);
  })->active();

/* 
* The raw query for above statement converts as:

select * from `table_a` 
where exists (
   select * from `table_b` 
   where   `table_a`.`table_b_id` = `table_b`.`id` 
and `cancel_reason` = 'not_available' and `table_b`.`datetime` > now() and `table_b`.`deleted_at` is null) 
and `table_a`.`status` = 1 
*/