PHP: Conditionally add array members

Question

$headers=array(
     $requestMethod." /rest/obj HTTP/1.1",
     "listable-meta: ".$listablemeta,
     "meta: ".$nonlistmeta,
     'accept: */*',
      );

In the above example, I'd like to omit the whole line if $listablemeta or $nonlistmeta is blank. Assume $listablemeta is blank. Then the array would be:

$headers=array(
     $requestMethod." /rest/obj HTTP/1.1",
     "meta: ".$nonlistmeta,
     'accept: */*',
      );

Now I can setup a conditional isempty() and set the array accordingly, but what if I want to construct an array with say 20 different values each only setting if the variable on each line is not empty, is there another way to set a conditional -within- an array declaration? If not, what is another way to approach this problem?

Thanks!

Answer 1

Loop through your options array, and if the value isn't empty, add it to your headers array:

$headers = array(
  $requestMethod." /rest/obj HTTP/1.1",
  "meta: ".$nonlistmeta,
  'accept: */*'
);

$items = array(
  "item1" => "",
  "item2" => "foo"
);

foreach ($items as $key => $val) {
  if ($val != "") {
    $headers[] = $val; // only 'foo' will be passed
  }
}

Answer 2

I don't know about doing it in the declaration, but a simple helper function would propably do the trick:

function array_not_empty($values){
  $array = array();
  foreach($values as $key=>$value){
    if(!empty($value)) $array[$key] = $value;
  }
  return $array;
}

Answer 3

You can't do any conditionals inside the array clause that would help you with this, but this should suit your needs:

If the headers you want to pass to the array are as follows:

$requestMethod = 'GET';
$listablemeta = ''; // This shouldn't be in the final result
$nonlistmeta = 'non-listable-meta';

Build a key/value array of these variables:

$headers = array(
               0 => $requestMethod." /rest/obj HTTP/1.1",
               'listable-meta' => $listablemeta,
               'meta' => $nonlistmeta,
               'accept', '*/*'
           );

Note that if the value doesn't have a key as in requestMethod, just put a numeric value there. Then loop them through and build the final array:

function buildHeaders($headers) {
    $new = array();

    foreach($headers as $key => $value) {
        // If value is empty, skip it
        if(empty($value)) continue;
        // If the key is numerical, don't print it
        $new[] = (is_numeric($key) ? '' : $key.': ').$value;
    }

    return $new;
}

$headers = buildHeaders($headers);

$headers should now contain something like this:

$headers = array(
               'GET /rest/obj HTTP/1.1',
               'meta: non-listable-meta-here',
               'accept: */*'
           );