web services return more than 1 record

im dealing with web services and i face some problem with the List<>

DAL.cs

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.Collections.Generic;

namespace Data
{
    public class DAL
    {
        public static Model.customer GetCustomer(string custID)
        {
            string cs = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
            SqlConnection conn = null;
            SqlDataReader reader = null;
            try
            {
                conn = new SqlConnection(cs);
                string sql = "SELECT * FROM member WHERE userType = '" + custID + "'";
                SqlCommand cmd = new SqlCommand(sql, conn);
                conn.Open();
                reader = cmd.ExecuteReader();

                List<Model.customer> list = new List<Model.customer>();

                while (reader.Read())
                {
                    Model.customer cust = new Model.customer();
                    cust.customerID = reader["fullName"].ToString();
                    cust.contactName = reader["handphone"].ToString();
                    cust.companyName = reader["NRIC"].ToString();
                    list.Add(cust);
                }
                //error is here
                return list;
                //end of error
            }
            catch (Exception e)
            {
                HttpContext.Current.Trace.Warn("Error", "error in getcustomer()", e);
            }

            finally
            {
                if (reader != null) reader.Close();
                if (conn != null && conn.State != ConnectionState.Closed) conn.Close();
            }
            return null;
        }
    }
}

customer.cs

using System;

namespace Model
{    
    public class customer
    {
        private string _customerID;
        private string _companyName;
        private string _contactName;

        public string customerID
        {
            get { return _customerID; }
            set { _customerID = value; }
        }

        public string companyName
        {
            get { return _companyName; }
            set { _companyName = value; }
        }

        public string contactName
        {
            get { return _contactName; }
            set { _contactName = value; }
        }
    }
}

Service.cs

using System;
using System.Web;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Collections.Generic;

[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
public class Service : System.Web.Services.WebService
{
    public Service () {

    }

    [WebMethod]
    public static List<Model.customer> GetCustomer(string custID)
    {        
        return Biz.BAL.GetCustomer(custID);
    }
}

BAL.cs

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.Collections.Generic;

namespace Biz
{
    public class BAL
    {
        public static List<Model.customer> GetCustomer(string custID)
        {
            Model.customer cust = Data.DAL.GetCustomer(custID);
            cust.companyName = cust.companyName;
            List<Model.customer> myList = new List<Model.customer>();

            myList.Add(cust);
            
            return myList;
        }
    }
}

error: CS0029: Cannot implicitly convert type 'System.Collections.Generic.List<Model.customer>' to 'Model.customer'

Re: web services return more than 1 record

Make sure that return type of this method is correct. It should be List<Model.customer> not Model.customer

Re: web services return more than 1 record

hi, i update the first thread with all the class file, please advice me :)

im new to List<>

Re: web services return more than 1 record

Change the GetCustomer function like the following:

namespace Data
{
    public class DAL
    {
        public static List<Model.customer> GetCustomer(string custID)
        {
            string cs = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
            SqlConnection conn = null;
            SqlDataReader reader = null;
            try
            {
                conn = new SqlConnection(cs);
                string sql = "SELECT * FROM member WHERE userType = '" + custID + "'";
                SqlCommand cmd = new SqlCommand(sql, conn);
                conn.Open();
                reader = cmd.ExecuteReader();
                
                List<Model.customer> list = new List<Model.customer>();
                                
                while (reader.Read())
                {
                    Model.customer cust = new Model.customer();
                    cust.customerID = reader["fullName"].ToString();
                    cust.contactName = reader["handphone"].ToString();
                    cust.companyName = reader["NRIC"].ToString();
                    list.Add(cust);
                }
                return list;
            }
            catch (Exception e)
            {
                HttpContext.Current.Trace.Warn("Error", "error in getcustomer()", e);
            }

            finally
            {
                if (reader != null) reader.Close();
                if (conn != null && conn.State != ConnectionState.Closed) conn.Close();
            }
            return null;
        }
    }
}

The above method is returning a List of customers. If you want to return one customer, then keep the function return type as Model.customer and do not use List. Because List is only used when you are dealing with multiple recrods. Here it seems custID will have only one record.

Re: web services return more than 1 record

(actually the custID is memberType, i not yet change the variable, i wanted to list down all the member Type = 'member')

thanks for the reply, i used ur code, but now the error is transfer to BAL.cs so i modifed the code as below, unfortunately still got error.

public static List<Model.customer> GetCustomer(string custID)
{
Model.customer cust = Data.DAL.GetCustomer(custID);
cust.companyName = cust.companyName;
return cust;
}

Re: web services return more than 1 record

i think i need to update the customer.cs, but i duno how to.. :(

Re: web services return more than 1 record

Pay attention to your method return types. Earlier your method expected a single customer and you returned a list. Now your method expects a list, and you are returning a single customer. You may want to consider F#, which has strong type inference so that you don't have to keep declaring the return type incorrectly.

Re: web services return more than 1 record

i never learn f# before, and new to List<> ...

or can i modified the customer.cs to something like this?

private string _customerID;
        private string _companyName;
        private string _contactName;

	List<int> list = new List<int>();
        List.Add(_customerID);
        List.Add(_companyName);
        List.Add(_contactName);


        public string customerID
        {
            get { return _customerID; }
            set { _customerID = value; }
        }

        public string companyName
        {
            get { return _companyName; }
            set { _companyName = value; }
        }

        public string contactName
        {
            get { return _contactName; }
            set { _contactName = value; }
        }

Re: web services return more than 1 record

@melvintcs

Your function is declared to return an object fo type "List<Model.customer>". It currently returns an object of type "Model.customer"

To return a list change the code:

public static List<Model.customer> GetCustomer(string custID)
{
Model.customer cust = Data.DAL.GetCustomer(custID);
cust.companyName = cust.companyName;
//return cust;

//create the list object
List<Model.customer> myList = new List<Model.customer>();

//add the customer object to the list. You can add more if you like.

myList.Add(cust);

//return the list
return myList;
}

Re: web services return more than 1 record

Thanks, i took ur advice and modified the code, but still but minor error at DAL.cs, have a look :)

Re: web services return more than 1 record

@melvintcs

You're welcome :) Please mark the topic as answered if you're satisfied with the help.

Re: web services return more than 1 record

@fred-dk

how to solve that minor error? should i modified the customer.cs to List<> also?

how can i do so?

Re: web services return more than 1 record

Yes, since we actually return a List<Model.customer> the signature should read

public static List<Model.customer> GetCustomer(string custID)
        {
...
}

Re: web services return more than 1 record

i already apply this line of code at DAL.cs and BAL.cs,

but i cant apply at customer.cs :( , already import System.Collections.Generic

Re: web services return more than 1 record

What language/platform are you coming from? You mentioned you were new to List<T>, but most of your questions indicate you are somewhat new to C#. A method named GetCustomer indicates you want a single customer, but you are returning a list instead. Why? Perhaps by knowing where you are coming from will help us provide answers that make more sense.

Re: web services return more than 1 record

yes, it's a c#. returning a list of record is what i wanted. result >1 record

i think i almost there, but a little problem with the DAL.cs, got some minor error at that class.

Re: web services return more than 1 record

You are still specifying your return type as different than the actual returned value. Here, you return cust, which is of type Model.customer. Why then do you put List<Model.customer>? A List<> is like an array or a collection of items. Don't return a collection if you only want to return one.

melvintcs

public static List<Model.customer> GetCustomer(string custID)
{
Model.customer cust = Data.DAL.GetCustomer(custID);
cust.companyName = cust.companyName;
return cust;
}

should be:

public static Model.customer GetCustomer(string custID)
{
    Model.customer cust = Data.DAL.GetCustomer(custID);
    cust.companyName = cust.companyName;
    return cust;
}

Re: web services return more than 1 record

Your return type is also wrong here. I assume this is the problem you still face.

melvintcs

im dealing with web services and i face some problem with the List<>

DAL.cs

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.Collections.Generic;

namespace Data
{
    public class DAL
    {
        public static Model.customer GetCustomer(string custID)
        {
            string cs = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
            SqlConnection conn = null;
            SqlDataReader reader = null;
            try
            {
                conn = new SqlConnection(cs);
                string sql = "SELECT * FROM member WHERE userType = '" + custID + "'";
                SqlCommand cmd = new SqlCommand(sql, conn);
                conn.Open();
                reader = cmd.ExecuteReader();

                List<Model.customer> list = new List<Model.customer>();

                while (reader.Read())
                {
                    Model.customer cust = new Model.customer();
                    cust.customerID = reader["fullName"].ToString();
                    cust.contactName = reader["handphone"].ToString();
                    cust.companyName = reader["NRIC"].ToString();
                    list.Add(cust);
                }
                //error is here
                return list;
                //end of error
            }
            catch (Exception e)
            {
                HttpContext.Current.Trace.Warn("Error", "error in getcustomer()", e);
            }

            finally
            {
                if (reader != null) reader.Close();
                if (conn != null && conn.State != ConnectionState.Closed) conn.Close();
            }
            return null;
        }
    }
}

error: CS0029: Cannot implicitly convert type 'System.Collections.Generic.List<Model.customer>' to 'Model.customer'

This error means that you are trying to return a list, but your declared return type is Model.customer. You should use:

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.Collections.Generic;

namespace Data
{
    public class DAL
    {
        // Here I've changed your return type from Model.customer to List<Model.customer>.
        public static List<Model.customer> GetCustomer(string custID)
        {
            string cs = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
            SqlConnection conn = null;
            SqlDataReader reader = null;
            try
            {
                conn = new SqlConnection(cs);
                string sql = "SELECT * FROM member WHERE userType = '" + custID + "'";
                SqlCommand cmd = new SqlCommand(sql, conn);
                conn.Open();
                reader = cmd.ExecuteReader();

                List<Model.customer> list = new List<Model.customer>();

                while (reader.Read())
                {
                    Model.customer cust = new Model.customer();
                    cust.customerID = reader["fullName"].ToString();
                    cust.contactName = reader["handphone"].ToString();
                    cust.companyName = reader["NRIC"].ToString();
                    list.Add(cust);
                }
                //error is here
                return list;
                //end of error
            }
            catch (Exception e)
            {
                HttpContext.Current.Trace.Warn("Error", "error in getcustomer()", e);
            }

            finally
            {
                if (reader != null) reader.Close();
                if (conn != null && conn.State != ConnectionState.Closed) conn.Close();
            }
            return null;
        }
    }
}

You were almost there. Pay attention to your return types and make sure they are the same as the value you are returning.

Re: web services return more than 1 record

i uploaded my file, have a look

http://max-5.com.my/scripts/App_Code.rar