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I have a PHP array that I want to pass to the jQuery function that called it. However when I tried to retrieve the value of 'lat' the way i did below, I get the error Cannot read property 'lat' of null, obviously because I dont know how to access a multidimensional JSON array. Can anyone show me how?

PHP Array

Array
(
[0] => Array
    (
        [price] => 1600
        [bedroom] => 1
        [lat] => -71.119385
        [lng] => 42.373917
        [distance] => 6.65195429565453
    )

[1] => Array
    (
        [price] => 1800
        [bedroom] => 1
        [lat] => -71.104248
        [lng] => 42.368172
        [distance] => 4.957829810472103
    )
}

This gets encoded into

JSON

[{"price":"1600","bedroom":"1","lat":"-71.119385","lng":"42.373917","distance":"6.65195429565453"},{"price":"1800","bedroom":"1","lat":"-71.104248","lng":"42.368172","distance":"4.957829810472103"}]

jQuery

$(function() {
    $("#search_button").click(function(e){
        e.preventDefault();
        var search_location = $("#search_location").val();
        $.getJSON('index.php/main/get_places', {search_location: search_location}, function(json){
            $("#result").html(json.lat);
            console.log(json.lat);
        });
    });
});
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5 Answers

up vote 2 down vote accepted

json is an array, so it won't have the property lat.

Try:

json[0].lat

To get the first object's lat property, for example.

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console.log(json[0].lat); did not cause anything to be logged in the javascript console... –  Nyxynyx Oct 18 '11 at 2:33
    
Then the JSON is not what you say it is :) –  Hamish Oct 18 '11 at 2:34
    
I checked the JSON string returned without using AJAX. That's really the JSON lol... Does this have to do with the JSON string not having any index numbers like 1:, 2: –  Nyxynyx Oct 18 '11 at 2:35
    
Nope. see: jsfiddle.net/9TNSA –  Hamish Oct 18 '11 at 2:41
    
oh no.. I get the error Cannot read property '0' of null when using json[0].lat. Is there a way to check what is the json string received by the jquery function? –  Nyxynyx Oct 18 '11 at 2:47
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up vote 0 down vote 
$.getJSON('index.php/main/get_places', {search_location: search_location}, function(json){
  $.each(json, function(key, val) {
      console.log(val.lat);
  });
});
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up vote 0 down vote

Your json is returning as an array of objects, so you need to reference the scalar first. Change your references to json.lat into json[0].lat.

Then, if you need to you can write a for loop and reference it as json[i].lat, assuming that i is your iterator variable.

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up vote 0 down vote

json is an array of objects, just as it is in your php code.

So there are two lat values:

json[0].lat  // and
json[1].lat
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up vote 0 down vote

The json variable itself is null, as stated by the error message. All the answers about accessing subindexes of json or iterating over it like an array will fail because of this.

Look at the documentation for jQuery's getJSON and parseJSON. getJSON passes the server's response through parseJSON to convert it to a Javascript object. parseJSON returns null "if you pass in nothing, an empty string, null, or undefined."

I would use your browser's debugger to look at the raw http response from the server, because that is likely the culprit.

http://api.jquery.com/jQuery.getJSON/

http://api.jquery.com/jQuery.parseJSON/

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