Calling ASMX Web Service from Javascript

Question

I want to call a webservice from javascript.

This is my code:

 var method="GetStock";
 var url = "http://www.mywebsite.ro/ServiceGetStock.asmx";
 $.ajax({
 type: "POST",
 url: url + "/GetStock",
 data: "{variant_id='1'}",
 contentType: "application/json; charset=utf-8",
 dataType: "json",
 success: OnSuccessCall,
 error: OnErrorCall
 });
 function OnSuccessCall(response) {
 alert(response.d);
 }
 function OnErrorCall(response) {
 alert(response.status + " " + response.statusText);
 }

My ServiceGetStock.asmx code:

 [WebMethod]
 public string GetStock(int variant_id)
 {
 try
 {
 ProductVariant variant = ProductVariantManager.GetProductVariantByID(variant_id);
 return variant.Stock.ToString();
 }
 catch (Exception ex)
 {
 return ex.Message;
 }
 }

I got the error message:

POST http://www.mywebsite.ro/ServiceGetStock.asmx/GetStock 500 (Internal Server Error)

[UPDATE]

I forgot to mention that I added in webconfig of project(with webservice) because I got the error:

XMLHttpRequest cannot load http://www.mywebsite.ro/ServiceGetStock.asmx/HelloWorld. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http:// localhost:11300' is therefore not allowed access.

 <httpProtocol>
 <customHeaders>
 <add name="Access-Control-Allow-Origin" value="*" />
 <add name="Access-Control-Allow-Headers" value="Content-Type" />
 </customHeaders>
 </httpProtocol>

• Habib: What is the method signature for your GetStock
• Mike Marks: Use Fiddler (fiddler2.com) to emulate the POST request (using the Composer tab) and take a look at your response - this will tell you specifically the detailed error message you're actually receiving.
• Jason P: 500 is a server-side error. Have you debugged the server-side code? Also, "{id='1'}" isn't valid json, and id != variant_id. I'd imagine that matters.
• Mike Marks: Try {"variant_id":"1"}
• POIR: Ok. I changed id into variant_id. It was my mistake. But I got the same error.

Answer 1

Ok guys. I found the problem. When an ASMX file is created, you must read all comments lines. To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.

 //[System.Web.Script.Services.ScriptService]

So the GetStock function is:

 [WebMethod]
 [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
 public string GetStock(string variant_id)
 {
 SendEmail.SendErrorMail("in"+ variant_id);
 try
 {
 ProductVariant variant = ProductVariantManager.GetProductVariantByID(Convert.ToInt32(variant_id));
 return variant.Stock.ToString();
 }
 catch (Exception ex)
 {
 return ex.Message;
 }
 }

and the Ajax code is:

 var url = "http://www.mywebsite.ro/ServiceGetStock.asmx";
 $.ajax({
 type: "POST",
 url: url + "/GetStock",
 data: "{variant_id:'1'}",
 contentType: "application/json; charset=utf-8",
 dataType: "json",
 success: OnSuccessCall,
 error: OnErrorCall
 });
 function OnSuccessCall(response) {
 alert(response.d);
 }
 function OnErrorCall(response) {
 alert(response.status + " " + response.statusText);
 }

Problem solved! Thanks all for tips.......

• Si8: Going directly to this: http://myserver:123/WServ/EDt.asmx/HelloWorld displays the xml. But when I do the above I already get a 0 error. Any idea why?
• POIR: @Si8 what error do you get? Show us the error message.
• Si8: Here is my question: stackoverflow.com/questions/41752213/…
• FrenkyB: Do you have to use absolute url? Relative link is not working out for you?

Answer 2

use dataType: "jsonp", instead of dataType: "json", jsonp is for cross domian webservice. hope it will help.