JSON encode the first column of a 2d array

Question

I need to encode just the first column of an array with n rows.

Array (
[0] => Array
    (
        [FamilyName] => Dikkartan, Bartu
        [Balance] => -2446.91
        [Mobile] => 0444497
        [HAddress] => 2/6 Tramsway Street
        [HSuburb] => Rosebery
        [HState] => NSW
        [HPCode] => 

    )

[1] => Array
    (
        [FamilyName] => King, Alan & Luka
        [Balance] => -1676
        [Mobile] => 0433 6090
        [HAddress] => 46/12 Hayberry Street
        [HSuburb] => Crows Nest
        [HState] => NSW
        [HPCode] => 

    ) ...

How can I make an encoded string from the FamilyName column values.

Answer 1

Using array_map you can reduce the array to just that element.

$familyNames = array_map(function($object) {
    return $object['FamilyName'];
}, $objects);

json_encode($familyNames);

This uses an anonymous function available in php 5.3 otherwise you need to use create_function or a reference to an existing function you've created. See the PHP callback documentation.

create_function('$object', 'return $object["FamilyName"];')

Alternatively you could use a simple foreach loop:

$familyNames = array();
foreach($objects as $object)
    $familyNames[] = $object['FamilyName'];