Wsrtjtyk

I am getting phone contacts into a list<> and saving it in a database.
Below is my code.

This is my method to get the contacts-List

protected override void OnCreate(Bundle bundle) {

    base.OnCreate(bundle);

    try {

        SetContentView(Resource.Layout.Main);

        TextView txtcount = this.FindViewById<TextView>(Resource.Id.textView1);



        List<PersonContact> a1 = GetPhoneContacts();



        Phone gp = new Phone();



        gp.insertContact(a1);

    } catch (System.Exception ex) {

        alert(ex.Message);

    }

}

Via the following method I am trying to store contacts in database

[WebMethod]

public string insertContact<T>(List<PersonContact> a) {

    OpenConnection();

    if (a.Count > 0) {

        for (int i = 0; i < a.Count; i++) {

            string str = "insert into phone_contact (FirstName,LastName,PhoneNumber)values('" + a[i].FirstName + "','" + a[i].LastName + "','" + a[i].PhoneNumber + "')";

            SqlCommand cmd = new SqlCommand(str, con);

            cmd.ExecuteNonQuery();

        }

        return "1";

    } else {

        return "1";

    }

}



public class PersonContact {

    public string FirstName { get; set; }

    public string LastName { get; set; }

    public string PhoneNumber { get; set; }

}

I am getting an error while passing parameter

 gp.insertContact(a1);

Your method is generic, as it introduces a new type parameter T. That's what the <T> at the end of the method name means.

However, you don't use T anywhere - so just make it a non-generic method:

public string InsertContact(List<PersonContact> a)

At the same time, I would very strongly urge you to change the way you're doing database access: it's currently vulnerable to SQL injection attacks. Instead, you should use parameterized SQL: have one parameter for each of FirstName, LastName and PhoneNumber.

You're also returning "1" regardless of the input. Your method could be written more simply as:

// Consider renaming to InsertContacts, as it's not just dealing with a single

// contact

public string InsertContact(List<PersonContact> contacts)

{

    // You should almost certainly use a using statement here, to

    // dispose of the connection afterwards

    OpenConnection();

    foreach (var contact in contacts)

    {

        // Insert the contact. Use a using statement for the SqlCommand too.

    }

    return "1";

}

That's assuming you need the value returned at all - if you're always returning the same value, why not just make it a void method?