How To Sort Empty key & value in lower order if its null in php

Question

What I need

• i Need when [comment]='' Field is Null Then it Should be sort & it would result in lower order.

• Array Structure

  [0] => Array
  (
      [type] => CACDA
      [metadata] => Array
          (
              [0] => Array
                  (
                      [amount] => 320
                      [comment] => 
                  )
  
          )
  
  )
  
   [1] => Array
  (
      [type] => CVMA
      [metadata] => Array
          (
              [0] => Array
                  (
                      [amount] => 320
                      [comment] => Onsite After February 20
                  )
  
          )
  
  )
  

source code

              unset($data[0]);
            //store types and the arrays the belong to    
                foreach($data as $k=>$v){
                $type[$v['type']][]=$k;
                }

                //loop types, creating result array
                foreach($type as $k=>$v){
                $tmp=array(
                'type'=>$k,
                'metadata'=>array()
                );
                //loop all the arrays of this type
                foreach($v as $w){
                //store in TMP
                $t=array(
                'amount' => $data[$w]['amount'],
                'comment' => $data[$w]['comment']
                );

               $t array structure

                                                                                 Array
                                    (
                                    [amount] => 320
                                    [comment] => 
                                    )
                                    Array
                                    (
                                    [amount] => 320
                                    [comment] => Onsite After February 20
                                    )
                                    Onsite After February 20Array
                                    (
                                    [amount] => 320
                                    [comment] => Onsite After February 20
                                    )
                                    Onsite After February 20Array
                                    (
                                    [amount] => 370
                                    [comment] => Onsite After February 20
                                    )
                                    Onsite After February 20Array
                                    (
                                    [amount] => 170
                                    [comment] => Onsite After February 20
                                    )
                //sort TMP on EMPTY value
                //usort($t,function ($a, $b) {
                //if($a == '' && $b != '') return 1;
                //if($b == '' && $a != '') return -1;
                //if($b == 0){return 1;}
                //return 0; 
                //});
                arsort($t['comment']);
                //store 
                $tmp['metadata'][]=$t;
                }
                $result[]=$tmp;
                }

output of array after sorting Should come Like ex

      [1] => Array
    (
        [type] => CVMA
        [metadata] => Array
            (
                [0] => Array
                    (
                        [amount] => 320
                        [comment] => Onsite After February 20
                    )

            )

    )
   [0] => Array
    (
        [type] => CACDA
        [metadata] => Array
            (
                [0] => Array
                    (
                        [amount] => 320
                        [comment] => 
                    )

            )

    )

• problem i having i have also tried with usort .

• i have tried with arsort function but nothing is working for sorting .

• please suggest where i have done wrong .

• which sorting function i should use for key & value in php.

Answer 1

You can use uasort.

uasort($array, function($a) {
     return ( is_null($a['metadata'][0]['comment']) OR $a['metadata'][0]['comment'] == "") ? 1 : -1;
});

https://eval.in/207091