scrub nulls from php array

Question

i am having problems with a function that is supposed to return all the childern of a certian object and encode the whole thing into JSON. Currently it is working but there are a bunch of nulls in the JSON encode and i have tried array_filter() and a foreach loop to scrub them out, both didn't work.

findChildren($conn, $topic);

$data = array();
function findChildren($conn, $topic) {
   $rst = $conn->query("SELECT topicID, topicTitle, topicParentID, topicDeleted FROM tbl_topics WHERE topicParentID = $topic");
   while ($row = $rst->fetch_assoc()) {
      if ($row['topicDeleted'] == 0) {
         //$data[] = htmlentities($row, UTF-8);
         if($row != '') {
            $data[] = $row;   
         }

         findChildren($conn, $row['topicID']);
      }              
   }
   echo json_encode( $data );
}

any help would be awesome. Thanks.

please provide a sample json output, and a sample query result. — , Oct 12 '12 at 21:47
you're worried about NULLs in the individual columns of $row, correct? — blackcatweb, Oct 12 '12 at 21:49
Seems that doing this solution on $row would work out. http://stackoverflow.com/questions/3654295/remove-empty-array-elements , although you said you tried array_filter() already. Why didn't that work? — blackcatweb, Oct 12 '12 at 21:55
`if ($row != '')` doesn't make sense. `$row` is an array, not a string. — Barmar, Oct 12 '12 at 21:55
You shouldn't have `echo json_encode($data)` in the function, because it's recursive. Each time it recurses, it echoes the accumulated rows. You shouldn't do that until the outermost call returns. — Barmar, Oct 12 '12 at 22:02

score 0 · Accepted Answer · answered Oct 12 '12 at 22:00

<?php

$data = findChildren($conn, $topic);
echo json_encode($data);

function findChildren($conn, $topic) {
    $data = array();
    $rst  = $conn->query(
        "
            SELECT topicID, topicTitle, topicParentID, topicDeleted
            FROM tbl_topics
            WHERE topicParentID = ${topic} and topicDeleted = 0
        "
    );

    while ($row = $rst->fetch_assoc()) {
        $data[] = array_filter($row);

        if(!empty($row['topicID'])) {
            $data = array_merge(
                $data,
                findChildren($conn, $row['topicID'])
            );
        }
    }

    return $data;
}

Changed the function to return an array, rather then echo directly, or use variable as if it was global
Moved the 'topicDeleted' checking to the query

scrub nulls from php array

1 Answers1