Question

I have a Web page within my application that needs to call a web service I have set up to return a list of objects. This call is set up like so

$(document).ready(function() {
    var response = $.ajax({
        type: 'POST',
        contentType: 'application/json; charset=utf-8',
        url: '/Ajax/service.asmx/GetObjects'
    });

    response.success(function(data) {
       $('#bodyText').html(data);
    });

    response.complete(function() {
       alert('ajax complete');
    });

});

My service looks like this

namespace AjaxTest.Ajax
{
    #region
using System.ComponentModel;
using System.Web.Script.Serialization;
using System.Web.Script.Services;
using System.Web.Services;

#endregion

/// <summary>
/// Summary for boat
/// </summary>
[WebService(Namespace = "http://quality/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.Web.Script.Services.ScriptService]
public class Boat : WebService
{
    #region Public Methods and Operators

    /// <summary>
    /// The Get Models method.
    /// </summary>
    [WebMethod]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
    public void GetModels()
    {
        var models = Com.somedll.GetModels();
        var serializer = new JavaScriptSerializer();
        var response = models.Count != 0
                ? serializer.Serialize(models)
                : serializer.Serialize(new Error { Code = "500", Message = "Model Retrieval Failed" });
        this.Context.Response.Clear();
        this.Context.Response.ContentType = "application/json";
        this.Context.Response.Flush();
        this.Context.Response.Write(response);
    }

    #endregion
    }
}

I am getting the following errors Server cannot append header after HTTP headers have been sent.
and looking at Firebug the request seems to be being sent multiple times at least 4 for each request, can anyone help. Please let me know if you need any more information

Answer 1

Move your Response.Write call before your call to Flush.

    this.Context.Response.Write(response);
    this.Context.Response.Flush();

UPDATE: You can also try removing the ContentType setter, since you’re already stating that your response type is JSON.