prabu R prabu R - 2 months ago 11
Ajax Question

Make cross-domain ajax JSONP request with jQuery

I would like to parse JSON array data with jquery ajax with the following code:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Sample</title>
<script type="text/javascript" src="Scripts/jquery-1.7.2.min.js"></script>
<script type="text/javascript">
var result;
function jsonparser1() {
$.ajax({
type: "GET",
url: "http://10.211.2.219:8080/SampleWebService/sample.do",
dataType: "jsonp",
success: function (xml) {
alert(xml.data[0].city);
result = xml.code;
document.myform.result1.value = result;
},
});
}
</script>
</head>
<body>
<p id="details"></p>
<form name="myform">
<input type="button" name="clickme" value="Click here to show the first name" onclick=jsonparser1() />
<input type="text" name="result1" readonly="true"/>
</form>
</body>
</html>


My JSON data is:

{"Data": [{"Address":"chetpet","FirstName":"arulmani","Id":1,"LastName":"sathish","City":"chennai"},{"Address":"ramapuram","FirstName":"raj","Id":2,"LastName":"nagu","City":"chennai"},{"Address":"ramapuram","FirstName":"raj","Id":2,"LastName":"nagu","City":"chennai"},{"Address":"ramapuram","FirstName":"ramaraj","Id":3,"LastName":"rajesh","City":"chennai"},{"Address":"ramapuram","FirstName":"yendran","Id":3,"LastName":"sathi","City":"chennai"}],"Code":true}


But i am not getting any output...anybody please help out...

Answer

Concept explained

Are you trying do a cross-domain AJAX call? Meaning, your service is not hosted in your same web application path? Your web-service must support method injection in order to do JSONP.

Your code seems fine and it should work if your web services and your web application hosted in the same domain.

When you do a $.ajax with dataType: 'jsonp' meaning that jQuery is actually adding a new parameter to the query URL.

For instance, if your URL is http://10.211.2.219:8080/SampleWebService/sample.do then jQuery will add ?callback={some_random_dynamically_generated_method}.

This method is more kind of a proxy actually attached in window object. This is nothing specific but does look something like this:

window.some_random_dynamically_generated_method = function(actualJsonpData) {
    //here actually has reference to the success function mentioned with $.ajax
    //so it just calls the success method like this: 
    successCallback(actualJsonData);
}

Summary

Your client code seems just fine. However, you have to modify your server-code to wrap your JSON data with a function name that passed with query string. i.e.

If you have reqested with query string

?callback=my_callback_method

then, your server must response data wrapped like this:

my_callback_method({your json serialized data});
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