CODEWITHSUNDEEP
javascriptjson
Darwin Tech
Darwin Tech

Reputation: 18919

get value from json in javascript

Hi I have a simple JSON output:

"{
   \"max_output_watts\": 150, 
   \"frame_length_inches\": \"62.20\",
   \"frame_width_inches\": \"31.81\"
 }"

which I use in a function like so:

...
$.getJSON(pop_model_dims_url, {model_id: selected}, function(data, jqXHR){
              alert(data.max_output_watts);
          });
...

The alert is just a placeholder for now, but I don't understand why the alert value is 'undefined'. If I do:

...
$.getJSON(pop_model_dims_url, {model_id: selected}, function(data, jqXHR){
              alert(data);
          });
...

I get the full json dump as expected.

Any help much appreciated.

Upvotes: 4

Views: 552

Answers (4)

iMoses
iMoses

Reputation: 4348

jQuery getJSON should parse the JSON by himself. If the JSON comes like that:

"{
   \"max_output_watts\": 150, 
   \"frame_length_inches\": \"62.20\",
   \"frame_width_inches\": \"31.81\"
 }"

The parser mistaken it for a string.

It should come out as plain text like this:

{
   "max_output_watts": 150, 
   "frame_length_inches": "62.20",
   "frame_width_inches": "31.81"
 }

Upvotes: 1

felipeclopes
felipeclopes

Reputation: 4070

You have to parse to JSON, because it looks like not a json, since the method is undefined:

Here is the notation with jQuery:

data = $.parseJSON(data);

data.max_output_watts;

And here is how you should do without:

data = JSON.parse(data);

data.max_output_watts;

Regards!

Upvotes: 0

I Hate Lazy
I Hate Lazy

Reputation: 48761

Since your alert(data); gives you the full JSON dump, this likely means that the JSON has been double encoded on the server.

jQuery will have parsed it once for you, but you'd need to parse it again.

$.getJSON(pop_model_dims_url, {model_id: selected}, function(data, jqXHR){
    data = $.parseJSON(data);
    alert(data.max_output_watts);
});

Of course this is not a proper fix. The proper solution is to fix it on the server.

Once you've done that, you won't need $.parseJSON anymore.

Upvotes: 5

Lukas_Skywalker
Lukas_Skywalker

Reputation: 2060

Your JSON is probably a string. You have to parse it first. Use

var obj = JSON.parse(data);
alert(obj.max_output_watts);

Upvotes: 3

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