Force json_encode to return array instead objects

Question

I've been wondering if it's possible to force json_encode into returning Array instead an Object while still keeping the "integer" index.

What am I trying to achieve if you're asking is an array of usernames ( with their userID's as keys in the array ).

So if I have a list of mutual friends like this in PHP:

1 => 'John Doe',
2 => 'Jane Doe',
5 => 'Oliver Natefield',
11 => 'Chris Cole'

I'd like to use json_encode and I tried two methods.

First one is by simply adding into an empty PHP Array, values to their respective index ( userID ).

<?php
    $list = array( );

    foreach ( $friends as $userID => $name )
        $list[ $userID ] = $name;

    echo json_encode( $list );
?>

That creates me an Object sadly. Ok, then I tried something else...

<?php
    $list = array( );

    foreach ( $users as $userID => $name )
        array_splice( $list, $userID, 0, $name );

    echo json_encode( $list );
?>

Again, failed, this time, it's an Array, but the indexes are not taken into consideration.

I know that.. the array should be like :

undefined, // userID 0
'John Doe', // userID 1
'Jane Doe', // userID 2
undefined, // userID 3
undefined,  // userID 4
'Oliver Natefield', // userID 5
undefined, //userID 6
undefined, // etc

But... if I have a friend with userID with the index 1504 .. shouldn't there be a memory downside ?

And while we're at it, can I see how much memory does an array of 1000 undefined elements use ? It's relevant because if it consumes too much memory, I'll just have to search through an array of objects for a username after a specific userID.

this list that you have.. it looks like a PHP array. Is that what it is? You are calling it "list", just be specific. — CodeGodie
– CodeGodie, Commented Mar 10, 2015 at 21:15

Marc B · Accepted Answer · 2015-03-10 20:52:54Z

5

This is not really possible. It's a restriction of Javascript syntax, which is basically what JSON is. You can't specify array keys in a Javascript "shortcut" array definition, like you can with PHP. e.g.

$foo = array(1 => 'a', 10 => 'b');

There's no such notation in JS, the only shortcut allowed is

foo = ['a', 'b'];

which would give you the PHP equivalent 0 => 'a', 1 => 'b'. To use non-sequential array keys, you MUST use an Object:

foo = {1: 'a', 10: 'b'};

answered Mar 10, 2015 at 20:52

Marc B

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1 Comment

Eduard Over a year ago

Yes.. I knew that but still there was hope ! Thanks anyway !

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