Develop Reference

How to get a json response from yaler

I create an account with yaler, to comunicate with my arduino yun. It works fine, and i'm able to switch on and off my leds.
Then i created a web page, with a button that calls an ajax function with GET method to yaler (yaler web server accept REST style on the URL)
$.ajax({
url: "http://RELAY_DOMAIN.try.yaler.net/arduino/digital/13/1",
dataType: "json",
success: function(msg){
var jsonStr = msg;
},
error: function(err){
alert(err.responseText);
}
});
This code seem to work fine, infact the led switches off and on, but i expect a json response in success function (msg) like this:
{
"command":"digital",
"pin":13,
"value":1,
"action":"write"
}
But i get an error (error function). I also tried to alert the err.responseText, but it is undefined....
How could i solve the issue? Any suggestions???
Thanks in advance....

If the Web page containing the above Ajax request is served from a different origin, you'll have to work around the same origin policy of your Web browser.
There are two ways to do this (based on http://forum.arduino.cc/index.php?topic=304804):
CORS, i.e. adding the header Access-Control-Allow-Origin: * to the Yun Web service
JSONP, i.e. getting the Yun to serve an additional JS function if requested by the Ajax call with a query parameter ?callback=?
CORS can probably be configured in the OpenWRT part of the Yun, while JSONP could be added to the Brige.ino code (which you seem to be using).

I had the same problem. I used JSONP to solve it. JSONP is JSON with padding. Basically means you send the JSON data with a sort of wrapper.
Instead of just the data you have to send a Java Script function and this is allowed by the internet.
So instead of your response being :
{"command":"digital","pin":13,"value":0,"action":"write"}
It should be:
showResult({command:"analog",pin:13,value:0,action:"write"});
I changed the yunYaler.ino to do this.
So for the html :
var url = 'http://try.yaler.net/realy-domain/analog/13/210';
$.ajax({
type: 'GET',
url: url,
async: false,
jsonpCallback: 'showResult',
contentType: "application/json",
dataType: 'jsonp',
success: function(json) {
console.dir(json.action);
},
error: function(e) {
console.log(e.message);
}
});
};
function showResult(show)
{
var str = "command = "+show.command;// you can do the others the same way.
alert (str);
}
My JSON is wrapped with a showResult() so its made JSONP and its the function I called in the callback.
Hope this helps. If CORS worked for you. Could you please put up how it worked here.

Get prayer time JSON data using JQUERY and Ajax

I want to READ JSON data using Jquery ana Ajax from this link
http://praytime.info/getprayertimes.php?lat=31.950001&lon=35.9333&gmt=180&m=3&y=2013&school=0&format=json&callback=?
and this is my code:
$(document).ready(function() {
var strUser ="http://praytime.info/getprayertimes.php?lat=31.950001&lon=35.9333&gmt=180&m=3&y=2013&school=0&format=json&callback=?";
$.ajax({
url: strUser ,
dataType: 'jsonp',
success: function(data){
jQuery.each(data, function(){
alert("yes");
});
}
});
});
I tried this code with other links , and it's correct, but from the specified link I don't get any out put, can you help me??

The url you are trying to access with JSONP doesnot support it. The server will need to return the response as JSON, but also wrap the response in the requested call back. So a way to solve this problem is using a server side proxy, which fetches the response from the specified url and passes it on to your client side js, like:
$.ajax({
type: "GET",
url: url_to_yourserverside_proxy,
dataType: "json",
success: function( data ) {
console.log(data);
}
});
where
url_to_yourserverside_proxy is a server side file that fetches response from the url specified

URL is outputting json but for cross domain need jsonp.
Not all API's provide jsonp. If cross domain API doesn't provide jsonp and isn't CORS enabled you will need to use a proxy to retrieve data due to same origin policy

Calling a web service in JQuery and assign returned Json to JS variable

This is my first time attempting working with JQuery, Json AND calling a web service.. So please bear with me here.
I need to call a webserivce using JQuery, that then returns a Json object that I then want to save to a javascript variable. I've attempted writing a little something. I just need someone to confirm that this is indeed how you do it. Before I instantiate it and potentially mess up something on my company's servers. Anyways, here it is:
var returnedJson = $.ajax({
type: 'Get',
url: 'http://172.16.2.45:8080/Auth/login?n=dean&p=hello'
});
So there it is, calling a webservice with JQuery and assigning the returned jsonObject to a javascript variable. Can anyone confirm this is correct?
Thanks in advance!

var returnedJson = $.ajax({
type: 'Get',
url: 'http://172.16.2.45:8080/Auth/login?n=dean&p=hello'
});
If you do it like this returnedJson would be an XHR object, and not the json that youre after. You want to handle it in the success callback. Something like this:
$.ajax({
// GET is the default type, no need to specify it
url: 'http://172.16.2.45:8080/Auth/login',
data: { n: 'dean', p: 'hello' },
success: function(data) {
//data is the object that youre after, handle it here
}
});

The jQuery ajax function does not return the data, it returns a jQuery jqHXR object.
You need to use the success callback to handle the data, and also deal with the same origin policy as Darin mentions.

Can anyone confirm this is correct?
It will depend on which domain you stored this script. Due to the same origin policy restriction that's built into browsers you cannot send cross domain AJAX requests. This means that if the page serving this script is not hosted on http://172.16.2.45:8080 this query won't work. The best way to ensure that you are not violating this policy is to use relative urls:
$.ajax({
type: 'Get',
url: '/Auth/login?n=dean&p=hello'
});
There are several workarounds to the same origin policy restriction but might require you modifying the service that you are trying to consume. Here's a nice guide which covers some of the possible workarounds if you need to perform cross domain AJAX calls.
Also there's another issue with your code. You have assigned the result of the $.ajax call to some returnedJson variable. But that's not how AJAX works. AJAX is asynchronous. This means that the $.ajax function will return immediately while the request continues to be executed in the background. Once the server has finished processing the request and returned a response the results will be available in the success callback that you need to subscribe to and which will be automatically invoked:
$.ajax({
type: 'Get',
url: '/Auth/login?n=dean&p=hello',
success: function(returnedJson) {
// use returnedJson here
}
});
And yet another remark about your code: it seems that you are calling a web service that performs authentication and sending a username and password. To avoid transmitting this information in clear text over the wire it is highly recommended to use SSL.

jQuery $.getJSON not working

I am try to get a URL from a one server and using that URL to get contents of another server.
$.ajax({url : 'http://localhost:8080/geturl.jsp?A=1&B=2,C=3',
success : function (data)
{
alert(data);
$.getJSON(data, function (mydata)
{
alert(mydata);
});
},
error : function (data, status, xhr)
{
}
});
I know that we cannot make cross-domain requests in through ajax call, thats why i am using getJSON, i have the following problems
When i simply pass the data to the url part of getJSON (as shown in the code), the alert-box show the correct URL but no get request is being performed ( get requests were monitored from FireBug).
When a hard-code the data to be "http://www.google.com" then the get request is being performed but the no response comes, although the response headers comes and response code is 200 (but it was marked as RED in the Firebug (Dont know why :( )
When I tries to fetch a webpage host in localhost domain, then it is fetched correctly although the response was not JSON.
I have the following doubts
If the getJSON function accecpts only JSON objects as reponse then why no error came when perform above 3.
Whats the correct code to perform my the required functionality.
Suggestions to what happened in each case
Thanks in advance for the answers :)

The getJSON function can only be used across domains to fetch JSONP.
It does not magically evade any security restrictions.

http://api.jquery.com/jQuery.ajax/
This should be a working example for jsonp:
var request = jQuery.ajax(
{
url: "http://Your url",
success: function (data) { console.log('success!'); console.log(data); },
error: function (data) { console.log('error!'); console.log(data); },
dataType: "jsonp",
type: "GET",
data: { key: 'value' }
});

jQuery JSONP, only works with same site URLs

I need to make a request to an API which returns json formatted data. This API is on a sub-domain of the domain this script will run off (although at the moment it's on a totally different domain for dev, localhost)
For some reason I thought that jsonp was supposed to enable this behavior, what am I missing?
Using jQuery 1.4.2
$.ajax({
url:'http://another.example.com/returnsJSON.php',
data: data,
dataType:'jsonp',
type: "POST",
error: function(r,error) {
console.log(r);
console.log(error);
},
success:function(r){
console.log(r);
}
});

Change your type from "POST" to "GET".
That is, only if you intend to retrieve data.

You'll need a combination of Arnaud's answer (don't use POST) and R. Bemrose's answer (make sure server-side returns JSONP), with the added specification of a callback function.
In other words, here's your modified request code:
function dosomething(data) {
console.log(data);
}
$.ajax({
url: 'http://another.example.com/returnsJSON.php',
data: data,
dataType: 'jsonp'
});
Helpful to note that in the generated code you'll see that when the dataType is "jsonp", jQuery outputs a script tag pointing at the url; it's not a typical XHR. You could also use jQuery's getJSON() here.
Then your response will have to be formatted as such:
dosomething({
test: 'foo'
});
When the call is complete, your specified callback will fire.

Did you modify the server-side component to use JSONP?
You can't just tell the client to use JSONP and suddenly expect a JSON script on the server-side to return the correct result.
Specifically, JSONP requires the server to return a JavaScript string that calls a specific function (whose name is passed in with the other arguments) with the return results, which the client then evals.