I would like json_encode in PHP to return a JSON array even if the indices are not in order

Question

but according to this: http://www.php.net/manual/en/function.json-encode.php#94157 it won't.

I'm using flot so I need to have an array with numeric indexes returned but what I'm getting is this:

jsonp1282668482872 ( {"label":"Hits 2010-08-20","data":{"1281830400":34910,"1281916800":45385,"1282003200":56928,"1282089600":53884,"1282176000":50262,"1281657600":45446,"1281744000":34998}} );

so flot is choking. If I var_dump the array right before I call json_encode it looks like this:

array(7) {
  [1281830400]=>
  int(34910)
  [1281916800]=>
  int(45385)
  [1282003200]=>
  int(56928)
  [1282089600]=>
  int(53884)
  [1282176000]=>
  int(50262)
  [1281657600]=>
  int(45446)
  [1281744000]=>
  int(34998)
}

any ideas?

Answer 1

As zneak says, Javascript (and thus JSON) arrays cannot have out-of-order array keys. Thus, you either need to accept that you'll be working with JSON objects, not arrays, or call array_values before json_encode:

json_encode(array_values($data));

However, it looks like you're looking to display time series data with flot. As you can see on the flot time series example, it should be a two element array like so:

$.plot(
  $('#placeholder'),
  [[
    [1281830400, 34910],
    [1281916800, 45385],
    [1282003200, 56928],
    [1282089600, 53884],
    [1282176000, 50262],
    [1281657600, 45446],
    [1281744000, 34998]
  ]],
  {
    label: 'Hits 2010-08-20',
    xaxis: {mode: 'time'}
  }
)

Given your array (let's call it $data) we can get the proper JSON like so:

json_encode(
  array_map(
    function($key, $value) { return array($key, $value); },
    array_keys($data),
    array_values($data)
  )
);

Answer 2

It's conceptually impossible. You cannot encode an array with fixed indices in JSON.

As a reminder, a JSON array looks like this:

[1, 2, 3, 4, 5]

There's no room to put indices there.

You should work on the Javascript side. Accepting that json_encode will return an object, you can convert this object into an array. That shouldn't be too hard.

function toArray(object)
{
    var result = [];
    for (var key in object)
    {
        if (!key.match(/^[0-9]+$/)) throw new Error("Key must be all numeric");
        result[parseInt(key)] = object[key];
    }
    return result;
}

Answer 3

You can force json_decode() to produce arrays by passing TRUE as the second parameter, but you can't force json_encode() to produce arrays in the first place:

json_decode($json, TRUE); // force array creation

Answer 4

You can use array_merge to reindex a numerically indexed array, like this:

$a = array(2 => 3, 4 => 5);
$a = array_merge($a);
var_dump($a);

Answer 5

For flot, what you're asking for isn't actually what you want. You want an array of arrays, not an array of numbers. That is, you want something that looks like this:

  [[1281830400, 34910],
   [1281916800, 45385],
   [1282003200, 56928],
   [1282089600, 53884],
   [1282176000, 50262],
   [1281657600, 45446],
   [1281744000, 34998]]

As for how to do that in PHP, I'm not sure.