Webmethod jquery ajax call not returning any results

Question

Hi I am building a web media gallery for which,

I've a simple webmethod to fetch tags from database.

public class Tags
        {
            public string tag_ID { get; set; }
            public string tag { get; set; }
            public string total_count { get; set; }
        }

        [WebMethod]
        public static List<Tags> GetTags()
        {
            using (SqlConnection conn = new SqlConnection())
            {
                conn.ConnectionString = ConfigurationManager.ConnectionStrings["taggerConnectionString"].ConnectionString;
                using (SqlCommand cmd = new SqlCommand())
                {
                    cmd.CommandText = "GetTagCount";
                    cmd.Connection = conn;
                    List<Tags> tag = new List<Tags>();
                    conn.Open();
                    using (SqlDataReader sdr = cmd.ExecuteReader())
                    {
                        while (sdr.Read())
                        {
                            tag.Add(new Tags
                            {
                                tag_ID = sdr["tag_ID"].ToString(),
                                tag = sdr["tag"].ToString(),
                                total_count = sdr["total_count"].ToString()
                            });
                        }
                    }
                    conn.Close();
                    return tag;
                }
            }
        }

and a javascript which I call on button click to display the result in a div. But I am not getting any result in the call. No errors are also being displayed.

 $(document).ready(function () { $('#getTags').click(myFunction); });

        function myFunction() {
            $.ajax({
                type: "POST",
                url: "/App/WebForm1.aspx/GetTags",
                data: '{}',
                contentType: "application/json; charset=utf-8",
                dataType: "json",
                success: OnSuccess,
                failure: function (response) {
                    alert(response.d);
                },
                error: function (response) {
                    alert(response.d);
                }
            });

            function OnSuccess(response) {
                var Tags = response.d;
                $(Tags).each(function () {
                    var tag = this.tag;
                    $("#results").append(" <b>" + tag + "</b>. ");
                })
            };
        }

Hi guys, I've separately tested all three suggestions given. No positive results yet. — Mashhoor Gulati, Aug 02 '17 at 18:20

score 1 · Answer 1 · answered Aug 02 '17 at 06:41

1

You are missing a line after cmd.CommandText = "GetTagCount"; it is cmd.CommandType = CommandType.StoredProcedure;

answered Aug 02 '17 at 06:41

Rahul

130
2

It didn't help. – Mashhoor Gulati Aug 02 '17 at 17:55
You were right. But that wasn't the root cause. My service was not being called at all. Thanks for help. – Mashhoor Gulati Aug 03 '17 at 01:02

score 0 · Answer 2 · answered Aug 02 '17 at 06:34

Setting this in Web.Config:

<system.web.extensions>
    <scripting>
      <webServices>
          <jsonSerialization maxJsonLength="2147483647"/>
      </webServices>
    </scripting>
</system.web.extensions>

You webservice code will be:

public class Tags
{
    public string tag_ID { get; set; }
    public string tag { get; set; }
    public string total_count { get; set; }
}

[WebMethod]
public static void GetTags()
{
    using (SqlConnection conn = new SqlConnection())
    {
        conn.ConnectionString = ConfigurationManager.ConnectionStrings["taggerConnectionString"].ConnectionString;
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.CommandText = "GetTagCount";
            cmd.Connection = conn;
            List<Tags> tag = new List<Tags>();
            conn.Open();
            using (SqlDataReader sdr = cmd.ExecuteReader())
            {
                while (sdr.Read())
                {
                    tag.Add(new Tags
                    {
                        tag_ID = sdr["tag_ID"].ToString(),
                        tag = sdr["tag"].ToString(),
                        total_count = sdr["total_count"].ToString()
                    });
                }
            }
            conn.Close();

            System.Web.Script.Serialization.JavaScriptSerializer jSearializer = new System.Web.Script.Serialization.JavaScriptSerializer();

            string result = jSearializer.Serialize(tag);
            System.Web.HttpContext.Current.Response.ContentType = "application/json";
            System.Web.HttpContext.Current.Response.Write(result);
            System.Web.HttpContext.Current.Response.End();                    
        }
    }
}

No result. No change. – Mashhoor Gulati Aug 02 '17 at 18:05 — Mashhoor Gulati, Aug 02 '17 at 18:05

score 0 · Answer 3 · answered Aug 03 '17 at 01:00

I guess I found the solution.

When I tried to troubleshoot using chrome's network tab..I got this result.

{"Message":"Authentication failed.","StackTrace":null,"ExceptionType":"System.InvalidOperationException"}

From which I understood that its because of configuration in template

in App_Start/RouteConfig.cs this line:

settings.AutoRedirectMode = RedirectMode.Permanent;

In one of the post on SO (Authentication failed during call webmethod from jquery.ajx with AspNet.FriendlyUrls and AspNet.Identity)

it was suggested to comment it.

Now since this is done. Can any one suggest pros & cons of commenting out this line. If its not a good idea from security point of view, any workaround.?

Webmethod jquery ajax call not returning any results

3 Answers3