How to Return a DataTable From WCF Service


Introduction

First we will create a simple WCF service that will return data of the Employees table as a DataTable object. Then we will consume this WCF service in a Console application.

Step 1: Create a new WCF Service Application named EmployeeSercice

wcf1.gif

Step 2: In IService1.cs, add ServiceContract and OperationContract:

[ServiceContract]
public interface IService1
{
    [OperationContract]
    Employee GetEmployee();
}

Then add DataContract and DataMember:

[DataContract]
public class Employee
{
    [DataMember]
    public DataTable EmployeeTable
    {
        get;
        set;
    }
}

In this article I am leaving binding to the default, wsHttpBinding.

Step 3: Add the following code in the Service1.svc.cs file inside Service1 class:

public class Service1 : IService1
{
    string ConString = ConfigurationManager.ConnectionStrings["ConString"].ConnectionString;
    SqlConnection con;
    SqlCommand cmd;
    SqlDataAdapter sda;
    DataTable dt;
    Employee emp = new Employee(); 
    public Employee GetEmployee()
    {            
        using (con = new SqlConnection(ConString))
        {
            cmd = new SqlCommand("SELECT EmployeeID, FirstName, LastName FROM Employees", con);
            sda = new SqlDataAdapter(cmd);
            dt = new DataTable("Paging");
            sda.Fill(dt);
            emp.EmployeeTable = dt;
            return emp;
        }       
    }
}

We have created our WCF service that will return Employees data as a DataTable. Now its time to consume this service in a Console application.

Step 4: Add a new Console Application named EmployeeServiceClient by right-clicking on the Solution Explorer and selecting Add -> New Project.

Step 5: Add a Service Reference to the WCF service in the Console Application using Add Service Reference dialog box.

Right-click on the Console Application and select Add Service Reference:

wcf2.gif

Step 6: Write following code in the Main function of the Console Application:

static void Main(string[] args)
{
    ServiceReference1.Service1Client MyClient =
        new ServiceReference1.Service1Client();
    ServiceReference1.Employee emp =
        new ServiceReference1.Employee();
    emp = MyClient.GetEmployee();
    DataTable dt = new DataTable();
    dt = emp.EmployeeTable;
    Console.WriteLine(" EmpID".PadRight(10)
        +"FirstName".PadRight(10)
        +"LastName".PadRight(10));
    Console.WriteLine("---------------------------------------");
    for (int i = 1; i < dt.Rows.Count; i++)
    {
        Console.WriteLine(dt.Rows[i][0].ToString().PadRight(10)+
            dt.Rows[i][1].ToString().PadRight(10) +
            dt.Rows[i][2].ToString().PadRight(10));
    } 
    Console.WriteLine(dt.Rows.Count.ToString());
    Console.ReadKey();
}

Step 7: In App.Config, change the maxReceivedMessageSize attribute value to maximum inside the Binding element to handle large tables.

maxReceivedMessageSize="2147483647"

Output

wcf3.gif

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