How to parse JSON array in jQuery?
Solution 1
No, with eval
is not safe, you can use JSON parser that is much safer: var myObject = JSON.parse(data);
For this use the lib https://github.com/douglascrockford/JSON-js
Solution 2
I know this is pretty long after your post, but wanted to post for others who might be experiencing this issue and stumble across this post as I did.
It seems there's something about jquery's $.each
that changes the nature of the elements in the array.
I wanted to do the following:
$.getJSON('/ajax/get_messages.php', function(data) {
/* data:
[{"title":"Failure","details":"Unsuccessful. Please try again.","type":"error"},
{"title":"Information Message","details":"A basic informational message - Please be aware","type":"info"}]
*/
console.log ("Data0Title: " + data[0].title);
// prints "Data0Title: Failure"
console.log ("Data0Type: " + data[0].type);
// prints "Data0Type: error"
console.log ("Data0Details: " + data[0].details);
// prints "Data0Details: Unsuccessful. Please try again"
/* Loop through data array and print messages to console */
});
To accomplish the loop, I first tried using a jquery $.each
to loop through the data array. However, as the OP notes, this doesn't work right:
$.each(data, function(nextMsg) {
console.log (nextMsg.title + " (" + nextMsg.type + "): " + nextMsg.details);
// prints
// "undefined (undefined): undefined
// "undefined (undefined): undefined
});
This didn't exactly make sense since I am able to access the data[0]
elements when using a numeric key on the data array. So since using a numerical index worked, I tried (successfully) replacing the $.each
block with a for loop:
var i=0;
for (i=0;i<data.length;i++){
console.log (data[i].title + " (" + data[i].type + "): " + data[i].details);
// prints
// "Failure (error): Unsuccessful. Please try again"
// "Information Message (info): A basic informational message - Please be aware"
}
So I don't know the underlying problem, a basic, old fashioned javascript for loop seems to be a functional alternative to jquery's $.each
Solution 3
Using .NET 3.5 FIX
All of you are slightly wrong, but the combination of all of your efforts has paid off!
Instead of eval('([' + jsonData + '])'); do
success: function(msg){
var data = eval(msg.d);
var i=0;
for(i=0;i<data.length;i++){
data[i].parametername /// do whatever you want here.
};
I don't know anything about the whole "don't use eval," but what I do know is that by doing the '([' + msg + '])' you are nesting those objects deeper, instead of up a level.
Solution 4
I am trying to parse JSON data returned from an ajax call, and the following is working for me:
Sample PHP code
$portfolio_array= Array('desc'=>'This is test description1','item1'=>'1.jpg','item2'=>'2.jpg');
echo json_encode($portfolio_array);
And in the .js, i am parsing like this:
var req=$.post("json.php", { id: "" + id + ""},
function(data) {
data=$.parseJSON(data);
alert(data.desc);
$.each(data, function(i,item){
alert(item);
});
})
.success(function(){})
.error(function(){alert('There was problem loading portfolio details.');})
.complete(function(){});
If you have multidimensional array like below
$portfolio_array= Array('desc'=>'This is test description 1','items'=> array('item1'=>'1.jpg','item2'=>'2.jpg'));
echo json_encode($portfolio_array);
Then the code below should work:
var req=$.post("json.php", { id: "" + id +
function(data) {
data=$.parseJSON(data);
alert(data.desc);
$.each(data.items, function(i,item){
alert(item);
});
})
.success(function(){})
.error(function(){alert('There was problem loading portfolio details.');})
.complete(function(){});
Please note the sub array key here is items, and suppose if you have xyz
then in place of data.items
use data.xyz
Solution 5
Careful with the eval, the JSON specs http://json.org/js.html recommend something like
var myObject = eval('(' + myJSONtext + ')');
And there may be some more gotchas. There is a plugin for jQuery that will take care of it, i guess:
user97410
Updated on July 05, 2022Comments
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user97410 almost 2 years
EDIT I checked the jQuery documentation and using $.ajax with the json datatype specified returns an evaluated javascript object, so eval() isn't the answer here. I knew that anyway, since I am able to parse single JSON objects, just not arrays. The problem is the $.each-ing my way through them :)
I have followed the syntax for parsing a JSON array in jQuery to the letter, but it doesn't work for some reason. I am fetching the array using $.ajax, have specified the correct datatype, and in Firebug can see that the response from my PHP script is []. Yet when I try to use $.each to iterate through the array, all I get is undefined values when I try to console.log various parts of the array. Here is where my php script makes and encodes the array:
if(mysqli_num_rows($new_res) > 0) { $messages = array(); while($message_data = mysqli_fetch_assoc($query_res)) { $message = array( 'poster' => $message_data['poster'], 'message' => $message_data['message'], 'time' => $message_data['time'] ); $messages[] = $message; } echo json_encode($messages); } else if(mysqli_num_rows($new_res) == 0) { $message = array( 'poster' => '', 'message' => 'No messages!', 'time' => 1 ); echo json_encode($message); }
And here is my attempt to parse it:
var logged_in = '<?php echo $logged_in; ?>'; var poster = '<?php echo $_SESSION["poster"];?>'; $.ajax({ url: 'do_chat.php5', type: 'post', data: ({'poster':poster,'logged_in':logged_in}), dataType: 'json', success: function(data) { $.each(data, function(messageIndex, message) { console.log(parseInt($('#chatWindow :last-child > span').html())+' '+message['time']); if((parseInt(message['time']) > parseInt($('#chatWindow :last-child > span').html()))) { $('#chatWindow').append('<div class="poster">'+message['poster']+'</div><div class="message"><span>'+message['time']+'</span>'+message['message']+'</div>'); } }); } });
Without the $.each function I am able to successfully parse single JSON objects, but not an array. This is my first outing with JSON and $.each, and I'm pretty new to jQuery, so go easy if my code has ugly bits!
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user97410 over 14 yearsDoes this not only work if the array that php jason_encodes is a single level array? For example, see the original code that generates the JSON object. Only in the event that the database query generates no results is the array one-dimensional, otherwise it is multidimensional.
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meder omuraliev over 14 yearsoh I didn't see that part.. hm
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meder omuraliev over 14 yearsOk - you should still be evaluating it, it's now a string at that point in your code I believe.
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meder omuraliev over 14 yearsFrom the JSON page:
The eval function is very fast. However, it can compile and execute any JavaScript program, so there can be security issues