object oriented approach from vb6 background

Question

i came from a vb6 background and I'm slowly testing the c# waters. my problem is i have difficulty in adapting an object oriented approach in my programs as i tend to pattern my programs the way i use to code in vb6. take for example this data entry part of software i am creating, as you see i am still coding it the way i code in vb6.

namespace WLMS
{
public partial class frmBA : Form
{
    enum status
    {
        add,
        edit,
        delete,
        complete,
        datafill,
    }

    status stat;
    clsSqlCommands sqlCommands = new clsSqlCommands();
    string connectionString = ConfigurationManager.ConnectionStrings["Main"].ConnectionString;
    int dataID = 0;


    public frmBA()
    {
        InitializeComponent();

    }

    private void displayInGrid()
    { 
        DataTable dt = new DataTable();
        dt = sqlCommands.dataFill("select series,baName,baLoc from tblBA order by baName",connectionString);
        if (dt != null)
        {
            dgBA_List.DataSource = dt;
            dgBA_List.Columns[0].HeaderText = null;
            dgBA_List.Columns[1].HeaderText = "BA NAME";
            dgBA_List.Columns[2].HeaderText = "BA LOCATION";
            dgBA_List.Columns[0].Visible = false;
            dgBA_List.Columns[1].Width = 100;
            dgBA_List.Columns[2].Width = 200;
            dataID = 0;        
        }
    }

    private void frmBA_Load(object sender, EventArgs e)
    {
        displayInGrid();
    }

    private void tlADD_Click(object sender, EventArgs e)
    {
        groupBox1.Enabled = true;
        clearTextBoxes(groupBox1);
        txtBAName.Focus();
        stat = status.add;
    }

    private void tlEDIT_Click(object sender, EventArgs e)
    {
        if (dataID != 0)
        {
            groupBox1.Enabled = true;
            stat = status.edit;
        }
        else
            MessageBox.Show("click on item to edit");
    }


    private void tlDELETE_Click(object sender, EventArgs e)
    {
        deleteData();
    }

    private void tlSAVE_Click(object sender, EventArgs e)
    {
        if (checkFilledTextBoxes(groupBox1) == true)
        {
            switch (stat)
            {
                case status.add:
                {
                    addNewData();
                    break;
                }
                case status.edit:
                {
                    editData();
                    break;
                }
                default:
                {
                    break;
                }
            }
        }

    }

    private bool checkForDuplicates()
    {
        DataRow dtr = sqlCommands.getOneRow("select count(*) as cnt from tblba where baName = '" + txtBAName.Text + "' and baLoc = '" + txtBALoc.Text + "'", connectionString);
        if (Convert.ToInt16(dtr["cnt"]) < 1)
        {
            return false;
        }
        else
            return true;
    }

    private void editData()
    {
        if (!checkForDuplicates())
        {
            sqlCommands.dataManipulate("update tblBa set baName = '" + txtBAName.Text + "',baLoc =  '" + txtBALoc.Text + "' where series = " + dataID + "", connectionString);
            clearTextBoxes(groupBox1);
            groupBox1.Enabled = false;
            stat = status.complete;
            displayInGrid();
            MessageBox.Show("Record Edited");
        }
        else
            MessageBox.Show("Duplicate record");
    }

    private void deleteData()
    {
        DialogResult dialogResult = MessageBox.Show("Are you sure?", "", MessageBoxButtons.YesNo);
        if (dialogResult == DialogResult.Yes)
        {
            sqlCommands.dataManipulate("delete from tblBa where series = " + dataID + "", connectionString);
            clearTextBoxes(groupBox1);
            groupBox1.Enabled = false;
            stat = status.complete;
            displayInGrid();
            MessageBox.Show("Record deleted");
        }
        else
            MessageBox.Show("Duplicate record");
    }

    private void addNewData()
    {
        if (!checkForDuplicates())
        {
            sqlCommands.dataManipulate("insert into tblBa (baName,baLoc) values ('" + txtBAName.Text + "','" + txtBALoc.Text + "')", connectionString);
            clearTextBoxes(groupBox1);
            txtBAName.Focus();
            stat = status.complete;
            displayInGrid();

            MessageBox.Show("Record Added");
        }
        else
            MessageBox.Show("Duplicate record");
    }

    private void clearTextBoxes(GroupBox gprx)
    {
        foreach (TextBox txtBx in gprx.Controls.OfType<TextBox>())
        {
            txtBx.Text = "";
        }
    }

    private Boolean checkFilledTextBoxes(GroupBox gprx)
    {
        foreach (TextBox txtBx in gprx.Controls.OfType<TextBox>())
        {
            if (txtBx.Text == "")
                return false;
        }
        return true;
    }

    private void tlEXIT_Click(object sender, EventArgs e)
    {
        this.Dispose();
    }

    private void dgBA_List_CellClick(object sender, DataGridViewCellEventArgs e)
    {
        int rowIndex = e.RowIndex;
        DataGridViewRow row = dgBA_List.Rows[rowIndex];
        dataID = Convert.ToInt16(row.Cells[0].Value);
        txtBALoc.Text = row.Cells[1].Value.ToString();
        txtBAName.Text = row.Cells[2].Value.ToString();
        groupBox1.Enabled = false;
    }
}
}

it has two textboxes that are inside a groupbox, one datagridview and 5 toolstrip buttons to add,edit,delete,save and exit. My question is, how can i restructure my code to have an object oriented approach?

PLEASE HELP.. thanks

Answer 1

As you are using a GUI, I would suggest a little reading on the MVC pattern (Winforms) Looking for clean WinForms MVC tutorial for C# or MVVM pattern (WPF) MVVM: Tutorial from start to finish?.

I would also suggest reading a decent design patterns book. The one that I found quite useful when first starting was the Head First Design Patterns book. Very easy to follow. The language they use is Java, but this is very syntactically close to C#.

Maybe also have a read of this excellent Martin Fowler article on GUI architectures: http://martinfowler.com/eaaDev/uiArchs.html

Edit: Following on from Dennis' comment. You may also have a look at the MVP pattern for Winform development. A couple of different ways of implementing that pattern: http://martinfowler.com/eaaDev/SupervisingPresenter.html and http://martinfowler.com/eaaDev/PassiveScreen.html

Answer 2

Simple answer - you can not.

Depending on technology.

• ASP.NET - use MVC, then it is natural.
• WPF: well, UI is in XAML anyway. Winforms: you can not, control are done in the designer and data bdinding is not too good.

The best yo ucan do in WInForms is actually not holding the logic in the form but in another object, but the form is done in the way the designer wants it, or you loose all compatibility.