Question

I’m not very good with ajax but I am trying to call a method in the code behind to cehck if a stored procedure is returning no data or returning data, and if it is returning data, then make the method return a bool evaluating to true. I am passing in a list of id’s to the method.
However my ajax call is probably wrong.

Here is my ajax:

var hasExhibitLinked = false;
            var selectedTasksList = getSelectedTaskIDs();

            $.ajax({
                type: "POST",
                url: '<%=ResolveUrl("~/Tasks/ViewTasks.aspx/HasExhibitLinked")%>',
                data: "{'taskID':['" + selectedTasksList.join(',') + "']}",
                contentType: "application/json; charset=utf-8",
                dataType: "json",
                success: function (data) {

                    arr = data.d;

                    hasExhibitLinked = arr[0];
                },
                error: function (data) {
                }
            });

            if (hasExhibitLinked) {
                showMessage("There is an Exhibit linked.");

            }
            else {
                showMessage("Not exhibits linked");

            }

here is my code behind if more information is needed:
EDIT:

[WebMethod]
public static bool[] HasExhibitLinked(String[] taskID)
{
    bool hasLink = false;
    var conn = new SqlConnection(ConfigurationManager.ConnectionStrings["OSCIDConnectionString"].ToString());
    var cmd = new SqlCommand("p_Link_List", conn);
        cmd.CommandType = CommandType.StoredProcedure;
    cmd.Parameters.Add(new SqlParameter("@Taskid", SqlDbType.Int));

    foreach (var id in taskID)
    {
        cmd.Parameters["@Taskid"].Value = taskID;
        try
        {
            conn.Open();
            String s = (String)cmd.ExecuteScalar();
            if (s != null)
                hasLink = true;
        }
        catch (SqlException sql)
        {
            ErrorLogger.Log(sql.Number, sql.Source, sql.Message);
        }
        catch (Exception ex)
        {
            ErrorLogger.Log(ex);
        }
        finally
        {
            if (conn.State == ConnectionState.Open)
                conn.Close();
        }
    }
    return new bool[] { hasLink };
}

Answer 1

taskID is an int in the code behind and an Array in the JavaScript.

data: "{'taskID':['" + selectedTasksList.join(',') + "']}",

would require a method signature like:

public static bool[] HasExhibitLinked(List<int> taskID)

---

Question Two in comments: This is a common mistake with ajax. That code is asynchronous. Therefore that variable doesn’t exist when you are trying to access it. This is why you see a lot of “callback” functions.

        var hasExhibitLinked = false;
        var selectedTasksList = getSelectedTaskIDs();

        $.ajax({
            type: "POST",
            url: '<%=ResolveUrl("~/Tasks/ViewTasks.aspx/HasExhibitLinked")%>',
            data: "{'taskID':['" + selectedTasksList.join(',') + "']}",
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: function (data) {

                arr = data.d;

                hasExhibitLinked = arr[0];
                // Now it exists and is ready
                if (hasExhibitLinked) {
                    showMessage("There is an Exhibit linked.");
                } else {
                    showMessage("Not exhibits linked");
                }
            },
            error: function (data) {
            }
        });