i have array of strings in JavaScript passed on the button click, here on button click the dataArray stores string value of first elements from the table in which some of the rows has been selected after that i stringify as JSON and call a Ajax function to send the data to my code behind function DeleteStudent.
my JavaScript function that i call on button click:

$('#deleteStudent').click(function () {
            var dataArr = [];
            $.each($("#StudentTable tr.selected"), function () {
                dataArr.push($(this).find('td').eq(0).text()); 
            });
            var StudentList = JSON.stringify(dataArr);
            $.ajax({
                type: "POST",
                url: "ViewStudents.aspx/DeleteStudent",
                contentType: "application/json; charset=utf-8",
                data: { Students: dataArr },
                dataType: "json",
                traditional: true,
                success: function (result) {
                    alert('Yay! It worked!');
                },
                error: function (result) {
                    alert('Oh no :(  : '+result);
                }
            });
            console.log(StudentList);
    });

the dataArray looks like this

["10363","10364","10366"]

the code behind function:

[WebMethod]
public static void DeleteStudent(string[] Students)
{
    Console.WriteLine("Reached CS");
    string[] a =Students;
    for (int i = 0; i < a.Length; i++)
    {
        string admissionNumber=a[i];
        using (MySqlConnection conn = new MySqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString))
        {
            using (MySqlCommand deleteStudent = new MySqlCommand())
            {
                deleteStudent.CommandType = CommandType.Text;
                deleteStudent.Connection = conn;
                deleteStudent.CommandText = "DELETE FROM validstudents WHERE admissionNumber = @admissionNumber ";

                deleteStudent.Parameters.AddWithValue("@admissionNumber", admissionNumber);

                conn.Open();
                deleteStudent.ExecuteNonQuery();
                conn.Close();
            }
        }
    }
}

it gives a 500 internal server

i have array of strings in JavaScript passed on the button click, here on button click the dataArray stores string value of first elements from the table in which some of the rows has been selected after that i stringify as JSON and call a Ajax function to send the data to my code behind function DeleteStudent.
my JavaScript function that i call on button click:

$('#deleteStudent').click(function () {
            var dataArr = [];
            $.each($("#StudentTable tr.selected"), function () {
                dataArr.push($(this).find('td').eq(0).text()); 
            });
            var StudentList = JSON.stringify(dataArr);
            $.ajax({
                type: "POST",
                url: "ViewStudents.aspx/DeleteStudent",
                contentType: "application/json; charset=utf-8",
                data: { Students: dataArr },
                dataType: "json",
                traditional: true,
                success: function (result) {
                    alert('Yay! It worked!');
                },
                error: function (result) {
                    alert('Oh no :(  : '+result);
                }
            });
            console.log(StudentList);
    });

the dataArray looks like this

["10363","10364","10366"]

the code behind function:

[WebMethod]
public static void DeleteStudent(string[] Students)
{
    Console.WriteLine("Reached CS");
    string[] a =Students;
    for (int i = 0; i < a.Length; i++)
    {
        string admissionNumber=a[i];
        using (MySqlConnection conn = new MySqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ConnectionString))
        {
            using (MySqlCommand deleteStudent = new MySqlCommand())
            {
                deleteStudent.CommandType = CommandType.Text;
                deleteStudent.Connection = conn;
                deleteStudent.CommandText = "DELETE FROM validstudents WHERE admissionNumber = @admissionNumber ";

                deleteStudent.Parameters.AddWithValue("@admissionNumber", admissionNumber);

                conn.Open();
                deleteStudent.ExecuteNonQuery();
                conn.Close();
            }
        }
    }
}

it gives a 500 internal server

• javascript
• c#
• jquery
• asp
• ajax

• Set traditional: true in your ajax request options. – AhmadReza Payan Commented Jul 3, 2016 at 4:20
• not working added that line – aashishkr Commented Jul 3, 2016 at 4:32

3 Answers 3

Always stringify JSON before sending it to a WebMethod

data: JSON.stringify({ Students: dataArr })

This will work(In javascript)

       var optionSelected ="me"
                    var id = { id: optionSelected };

                    $.ajax({
                        url: '@Url.Action("GetConnectionProvider", "Customers")',
                        contentType: "application/json;charset=utf-8",
                        data: JSON.stringify(id),
                        type: 'POST',
                        dataType: 'json',
                        success: function(datas) {


                        }
                    });
In Action

 public ActionResult GetConnectionProvider(int id)
{
   //write your code
}

Try by List<string> data

[WebMethod]
public static void DeleteStudent(string[] data)
{

else

 [WebMethod]
public static void DeleteStudent(List<string> data)
{   

   data: { data : dataArr },