jQuery JSON parse - "Object not defined" - php

Question

Currently working for the first time with JSON and with little experience of jQuery.
I have this function that gets triggered on "success" of $.ajax request:
function(data) {
$.each(data.notifications, function(notifications) {
alert('New Notification!');
});
}
However I get an error in the firebug console stating "object is undefined" "length = object.length".
The JSON response is:
["notifications",[["test would like to connect with you",{"Accept":"\/events\/index.php\/user\/connection?userId=20625101&action=accept","Decline":"\/events\/index.php\/user\/connection?userId=20625101&action=decline"}]]]
I guess it has something to do with the number of []s but the JSON was encoded by PHP using json_encode()
Any help would be appreciated!
Thanks :)

Answer 1

What you have is a JSON Array. I'm guessing you were looking for something like this:
{
"notifications": [
["test would like to connect with you",
{
"Accept": "\/events\/index.php\/user\/connection?userId=20625101&action=accept",
"Decline": "\/events\/index.php\/user\/connection?userId=20625101&action=decline"
}]
]
}
Although I think a better structure would be:
{
"notifications": [
{
"message": "test would like to connect with you",
"Accept": "\/events\/index.php\/user\/connection?userId=20625101&action=accept",
"Decline": "\/events\/index.php\/user\/connection?userId=20625101&action=decline"
}
]
}
This way notification becomes a property of the object, which means you can access it via data.notifications. Otherwise you'd have to access the notifications via data[1] (data[0] would contain the string "notifications" which essentially becomes meaningless).
The following example should give you an idea as far as setting up your data in PHP:
<?php
$array = array(
"notifications" => array(
array(
"message" => "Test would like to connect with you",
"Accept" => "/events/index.php/user/connection?userId=20625101&action=accept",
"Decline" => "/events/index.php/user/connection?userId=20625101&action=decline"
)
)
);
echo json_encode($array);
?>

Answer 2

Your PHP response should actually be:
{
"notifications": [
["test would like to connect with you",
{
"Accept":"\/events\/index.php\/user\/connection?userId=20625101&action=accept",
"Decline":"\/events\/index.php\/user\/connection?userId=20625101&action=decline"
}
]
]
}
Note that with the above, notification is a field inside the object that the string represents. That will allow you to iterate, the way you are doing it with $.each(..).
The way you are doing is it by having an array (note the initial [ and the last ] in the response). The error is because $.each invokes data.notification.length where .length is an operation on undefined.
PHP side code should be somewhat like below:
echo json_encode(array("notifications" => $notifications));
instead of (my guess):
echo json_encode(array("notification", $notifications));