sort & display array with most values first in response (php)

Question

I have the below:

        $myData = array();

        while ($list = oci_fetch_array($stid, OCI_ASSOC)) {
            array_push($myData, $list);
        }
    
        header('Content-Type: application/json');
        // echo json_encode($myData); 
        echo "{\"data\":" .json_encode($myData). "}"; // contains multiple arrays

In which via a sql query the contents populate a kendo grid table.. problem is first array is used by kendo to create the columns and first outputted array is smaller then most arrays thereafter...

How could I sort my output above to include/output my longest array first so my kendo will get all header data to populate max columns

Answer 1

To sort by the length of the inner arrays descending, you need to compare the length of the second parameter to the first in your callback; you need to return a positive, negative or zero value dependent on whether the length is greater than, less than or equal to the other. You can do this simply by subtraction. For example:

$myData = array(
    array('key2' => 'value1', 'key3' => 'value1', 'key4' => 'value4'),
    array('key4' => 'value4'),
    array('key1' => 'value1', 'key4' => 'value4'),
    array('key1' => 'value1', 'key2' => 'value1', 'key3' => 'value1', 'key4' => 'value4')
);

usort($myData, function ($a, $b) { return count($b) - count($a); });

print_r($myData);

Output:

Array
(
    [0] => Array
        (
            [key1] => value1
            [key2] => value1
            [key3] => value1
            [key4] => value4
        )
    [1] => Array
        (
            [key2] => value1
            [key3] => value1
            [key4] => value4
        )
    [2] => Array
        (
            [key1] => value1
            [key4] => value4
        )
    [3] => Array
        (
            [key4] => value4
        )
)

Demo on 3v4l.org

Note that rather than create JSON yourself, which can be error-prone, you can generate your desired output by json encoding a new array:

echo json_encode(array('data' => $myData));

Output (for my sample data):

{
    "data": [
        {
            "key1": "value1",
            "key2": "value1",
            "key3": "value1",
            "key4": "value4"
        },
        {
            "key2": "value1",
            "key3": "value1",
            "key4": "value4"
        },
        {
            "key1": "value1",
            "key4": "value4"
        },
        {
            "key4": "value4"
        }
    ]
}