Question

Please be gentle, as I’m still new to web programming and -very- new to Ajax!

I’ve created a C# function which extracts data from an mssql database, formats it to a json string and returns that. Now I need to make a call from my javascript (jQuery) slider through an aspx page that is related to the C# code file.

I have actually never done anything like this before, from what I could tell by googling I need to use xmlHttpRequest, but how exactly do I make the function get hold of this string?

It would be awesome if someone had some example code that shows how this works.

Answer 1

It’s relatively easy with jQuery if you mark the C# function as a [WebMethod] or make it part of a ASP.NET webservice. Both these techniques make it easy to have the response automatically converted into a JSON object by ASP.NET, which makes processing on the client easier (IMHO).

The example below is if the page has a WebMethod named GetData, but it’s trivial to change the URL if you create a service.

$.ajax({ url: "somepage.aspx/GetData", 
         method: "POST", // post is safer, but could also be GET
         data: {}, // any data (as a JSON object) you want to pass to the method
         success: function() { alert('We did it!'); }
});

On the server:

[WebMethod]
public static object GetData() {
    // query the data...
    // return as an anonymous object, which ASP.NET converts to JSON
    return new { result = ... };
}