Invalid Operation Exception in Windows Form Application

Question

I am consuming a WCF service in a Windows Forms application. My WCF service has two classes called FulltimeEmployee and ParttimeEmployee. I want to register users into Sql database by using Wcf Service with Windows Fomr Application based on employee type. The user type will come from emu type but I can not compile it and showing following errors ...

Invalid Operation Exception on this two line and Its also saying get or set value for the property member by the ListControl..

 private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
        {

            if (comboBox2.SelectedValue =="-1")//Error in this line
            {
                txtHourlyPay.Visible = false;
                txtHoursWorked.Visible = false;
                label6.Visible = false;
                label7.Visible = false;

            }
            else if (comboBox2.SelectedValue =="1")//Error on this line 
            {

                txtHourlyPay.Visible = true;
                txtHoursWorked.Visible = true;
                label6.Visible = true;
                label7.Visible = true;

            }
        }

Here is Code for FullTime and PartTime Employee Class..

[DataContract]
public class FullTimeEmployee : Employee
{
    public int AnnualSalary { get; set; }
}

[DataContract]
public class PartTimeEmployee : Employee
{
    public int HourlyPay { get; set; }
    public int HoursWorked { get; set; }
}

Here is the code form class..

 [KnownType(typeof(FullTimeEmployee))]
    [KnownType(typeof(PartTimeEmployee))]
    [DataContract(Namespace = "http://pragimtech.com/Employee")]
    public class Employee
    {
        private int _id;
        private string _name;
        private string _gender;
        private DateTime _dateOfBirth;

        [DataMember(Order = 1)]
        public int Id
        {
            get { return _id; }
            set { _id = value; }
        }

        [DataMember(Order = 2)]
        public string Name
        {
            get { return _name; }
            set { _name = value; }
        }

        [DataMember(Order = 3)]
        public string Gender
        {
            get { return _gender; }
            set { _gender = value; }
        }

        [DataMember(Order = 4)]
        public DateTime DateOfBirth
        {
            get { return _dateOfBirth; }
            set { _dateOfBirth = value; }
        }

        [DataMember(Order = 5)]
        public EmployeeType Type { get; set; }
    }

    public enum EmployeeType
    {
        FullTimeEmployee = 1,
        PartTimeEmployee = 2
    }
}

Here is WCF service code to register employee based on type:

public void SaveEmployee(Employee employee)
{
    string cs = ConfigurationManager.ConnectionStrings["DBCS"].ConnectionString;

    using (SqlConnection con = new SqlConnection(cs))
    {
        SqlCommand cmd = new SqlCommand("spSaveEmployee", con);
        cmd.CommandType = CommandType.StoredProcedure;

        SqlParameter parameterId = new SqlParameter
                {
                    ParameterName = "@Id",
                    Value = employee.Id
                };
        cmd.Parameters.Add(parameterId);

        SqlParameter parameterName = new SqlParameter
                {
                    ParameterName = "@Name",
                    Value = employee.Name
                };
        cmd.Parameters.Add(parameterName);

        SqlParameter parameterGender = new SqlParameter
                {
                    ParameterName = "@Gender",
                    Value = employee.Gender
                };
        cmd.Parameters.Add(parameterGender);

        SqlParameter parameterDateOfBirth = new SqlParameter
                {
                    ParameterName = "@DateOfBirth",
                    Value = employee.DateOfBirth
                };
        cmd.Parameters.Add(parameterDateOfBirth);

        SqlParameter parameterEmployeeType = new SqlParameter
                {
                    ParameterName = "@EmployeeType",
                    Value = employee.Type
                };
        cmd.Parameters.Add(parameterEmployeeType);

        if (employee.GetType() == typeof(FullTimeEmployee))
        {
            SqlParameter parameterAnnualSalary = new SqlParameter
                    {
                        ParameterName = "@AnnualSalary",
                        Value = ((FullTimeEmployee)employee).AnnualSalary
                    };
            cmd.Parameters.Add(parameterAnnualSalary);
        }
        else
        {
            SqlParameter parameterHourlyPay = new SqlParameter
                    {
                        ParameterName = "@HourlyPay",
                        Value = ((PartTimeEmployee)employee).HourlyPay,
                    };
            cmd.Parameters.Add(parameterHourlyPay);

            SqlParameter parameterHoursWorked = new SqlParameter
                    {
                        ParameterName = "@HoursWorked",
                        Value = ((PartTimeEmployee)employee).HoursWorked
                    };
            cmd.Parameters.Add(parameterHoursWorked);
        }

        con.Open();
        cmd.ExecuteNonQuery();
    }
}

Here is the Windows Form application code:

private void button1_Click(object sender, EventArgs e)
{
    MyService.HalifaxServiceClient myservice = new MyService.HalifaxServiceClient("NetTcpBinding_IHalifaxService");

    MyService.Employee employee = null;

    if (((MyService.EmployeeType)Convert.ToInt32(comboBox2.SelectedValue)) == MyService.EmployeeType.FullTimeEmployee)
    {
        employee = new MyService.FullTimeEmployee
                   {
                      Id = Convert.ToInt32(textBox1.Text),
                      Name = txtName.Text,
                      Gender = comboBox1.Text,
                      DateOfBirth = Convert.ToDateTime(txtDateOfBirth.Text),
                      Type = MyService.EmployeeType.FullTimeEmployee(comboBox2.SelectedValue),//Error
                      AnnualSalary = Convert.ToInt32(txtAnnualSalary.Text),
                   };
        myservice.SaveEmployee(employee);
        label8.Text = "Employee saved";
    }
    else if (((MyService.EmployeeType)Convert.ToInt32(comboBox2.SelectedValue)) == MyService.EmployeeType.PartTimeEmployee)
    {
        employee = new MyService.PartTimeEmployee
                       {
                           Id = Convert.ToInt32(textBox1.Text),
                           Name = txtName.Text,
                           Gender = comboBox1.Text,
                           DateOfBirth = Convert.ToDateTime(txtDateOfBirth.Text),
                           Type = MyService.EmployeeType.PartTimeEmployee(comboBox2.SelectedValue),//Error
                           HourlyPay = Convert.ToInt32(txtHourlyPay.Text),
                           HoursWorked = Convert.ToInt32(txtHoursWorked.Text),
                       };
        myservice.SaveEmployee(employee);
        label8.Text = "Employee saved";
    }
    else
    {
       label8.Text = "Please select Employee Type";
    }
}

private void button2_Click(object sender, EventArgs e)
{
    this.Close();
}



private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
    {

        if (comboBox2.SelectedValue =="-1")
        {
            txtHourlyPay.Visible = false;
            txtHoursWorked.Visible = false;
            label6.Visible = false;
            label7.Visible = false;

        }
        else if (comboBox2.SelectedValue =="1")
        {

            txtHourlyPay.Visible = true;
            txtHoursWorked.Visible = true;
            label6.Visible = true;
            label7.Visible = true;

        }
    }

When I click the submit button its shows the error message

and does not insert a new employee into SQL Server database..

Here is screenshot of output:

Please help me to correct this error ...

Answer 1

I think you want SelectedItem, not SelectedValue on your combobox. Take this code for example, which I think emulates your code:

    public partial class Form1 : Form
{
    public Form1()
    {

        InitializeComponent();
        comboBox2.Items.Add(Employee.FullTimeEmployee);
        comboBox2.Items.Add(Employee.PartTimeEmployee);
        comboBox2.SelectedIndexChanged += ComboBox1OnSelectedIndexChanged;
        label1.Text = "Full text: ";
        label2.Text = "Integer value: ";
    }

    private void ComboBox1OnSelectedIndexChanged(object sender, EventArgs eventArgs)
    {
        label1.Text = "Full text: " + ((ComboBox) sender).SelectedItem;
        label2.Text = "Integer value: " + (int)(Employee)(((ComboBox)sender).SelectedItem);
    }
}

public enum Employee
{
    FullTimeEmployee = 1,
    PartTimeEmployee = 2
}

From there you should get these results:

And you can see in the code to compare text you can just grab the selected item but to get the integer value you need to cast it to int. Hope this helps, happy coding!