Working with SQL Server using the MVP Pattern

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What is MVP?

The MVP design pattern is an Architecture Pattern used to build ASP.NET applications. It refers to splitting up the responsibilities for gathering, displaying, and storing information from a web page into separate objects: a Model object, a View object, and a Presenter object. The View is often an interface which is then implemented by an ASP.NET web page; the Model is a business object. The Presenter negotiates the transfer of data between the other two objects.

• View: View can be your ASPX page in your web application.
• Model: Model contains all the business logic.
• Presenter: Presenter is an intermediate between the Model and the View. It binds the View with the Model.

Getting Started

Step 1

Create folders Model, Presenter, and View in the project as shown in the figure:

Step 2

Create a new interface called IModel inside the Model folder to add the following code:

public interface IModel
{
    List<String> setInfo();
}

Step 3

Create a new class inside the Model folder and add the following code:

class Model : IModel
{
    // Adding Text to Label.
    public List<String> setInfo()
    {
        List<String> l = new List<string>();
        l.Add("ID:");
        l.Add("First Name:");
        l.Add("Last Name:");
        l.Add("Email Id:");
        l.Add("Phone No:");
        l.Add("Submit");
        l.Add("Data saved successfully.");
        return l;
    }
}

Note: We are adding string parameter - this string parameter will set to the Label in the ASPX page.

Step 4

Next moving to the View folder, create a new interface called IView and add the following code:

public interface IView
{
    string EmpIDLabel { get; set; }
    string EmpFirstNameLabel { get; set; }
    string EmpLastNameLabel { get; set; }
    string EmpMaildIDLabel { get; set; }
    string EmpPhoneNoLabel { get; set; }
    string EmpIDTextBox { get; set; }
    string EmpFirstNameTextBox { get; set; }
    string EmpLastNameTextBox { get; set; }
    string EmopMailIDTextBox { get; set; }
    string EmpPhoneNoTextBox { get; set; }
    string EmpButtonText { get; set; }
    string SuccessLabel { get; set; }
}

Step 5

Next, moving to the Presenter folder, create a new class called Presenter to add the following code:

public class Presenter
{
    IView _pView;
    IModel _pModel;

    public Presenter(IView PView, IModel PModel)
    {
        _pView = PView;
        _pModel = PModel;
    }

    // Here we are binding the string data to ASPX Label from the Model.
    public void BindModalView()
    {
        List<String> ls = _pModel.setInfo();
        _pView.EmpIDLabel = ls[0];
        _pView.EmpFirstNameLabel = ls[1];
        _pView.EmpLastNameLabel = ls[2];
        _pView.EmpMaildIDLabel = ls[3];
        _pView.EmpPhoneNoLabel = ls[4];
        _pView.EmpButtonText = ls[5];
    }

    // Inserting data to database table 
    string connection = 
      @"Data Source=RAVINDRA\MSSQLSERVERS;Initial Catalog=CrudMethod;Integrated Security=SSPI;";
    public void Save()
    {
        SqlConnection con = new SqlConnection(connection);
        SqlCommand cmd = con.CreateCommand();
        cmd.CommandText = "INSERT INTO Employee(Id,FirstName,LastName," + 
          "EmailId,phoneNo)VALUES(@Id,@FirstName,@LastName,@EmailId,@PhoneNo)";
        cmd.Parameters.AddWithValue("@Id", int.Parse(_pView.EmpIDTextBox));
        cmd.Parameters.AddWithValue("@FirstName", _pView.EmpFirstNameTextBox);
        cmd.Parameters.AddWithValue("@LastName", _pView.EmpLastNameTextBox);
        cmd.Parameters.AddWithValue("@EmailId", _pView.EmopMailIDTextBox);
        cmd.Parameters.AddWithValue("@PhoneNo", int.Parse(_pView.EmpPhoneNoTextBox));
        try
        {
            con.Open();
            cmd.ExecuteNonQuery();
            List<String> ls = _pModel.setInfo();
            _pView.SuccessLabel = ls[6]; // assigning the string from Model to the Label.
        }
        catch (SqlException ex)
        {

            throw ex;
        }
        finally
        {
            con.Close();
        }
    }
}

Step 6

Next step, add the following HTML code to your default.aspx page:

<%@ Page Language="C#" AutoEventWireup="true" 
               CodeBehind="Default.aspx.cs" Inherits="MVPDemo._Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
           "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>MVP Demo</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <center>
    <h2>MVP Pattern Demo</h2>
        <table>
            <tr>
                <td>
                    <asp:Label ID="Label1" runat="server" Text=""></asp:Label>
                </td>
                <td>
                    <asp:TextBox ID="txtID" runat="server"></asp:TextBox>
                </td>
            </tr>
            <tr>
                <td>
                    <asp:Label ID="Label2" runat="server" Text=""></asp:Label>
                </td>
                <td>
                    <asp:TextBox ID="txtFirstName" runat="server"></asp:TextBox>
                </td>
            </tr>
            <tr>
                <td>
                    <asp:Label ID="Label3" runat="server" Text=""></asp:Label>
                </td>
                <td>
                    <asp:TextBox ID="txtLastName" runat="server"></asp:TextBox>
                </td>
            </tr>
            <tr>
            <td>
             <asp:Label ID="Label4" runat="server" Text=""></asp:Label>
            </td>
            <td>
                <asp:TextBox ID="txtEmailID" runat="server"></asp:TextBox>
            </td>
            </tr>
            <tr>
            <td>
            <asp:Label ID="Label5" runat="server" Text=""></asp:Label>
            </td>
            <td>
                <asp:TextBox ID="txtPhoneNo" runat="server"></asp:TextBox>
            </td>
            </tr>
            <tr>
            <td colspan="2" align="center">
                <asp:Button ID="btnSubmit" runat="server" 
                Text="" onclick="btnSubmit_Click" />
            </td>
            </tr>
            <tr>
            <td>
            <asp:Label ID="Label6" runat="server" 
            Text="" ForeColor="Green"></asp:Label>
            </td>
            </tr>
        </table>
        </center>
    </div>
    </form>
</body>
</html>

Step 7

Next, in the Default.aspx.cs page, add the View members. Here we are assigning the Label and TexBox values to the View members.

#region IView Members
public string EmpIDLabel
{
    get
    {
        return Label1.Text;
    }
    set
    {
        Label1.Text = value;
    }
}
public string EmpFirstNameLabel
{
    get
    {
        return Label2.Text;
    }
    set
    {
        Label2.Text = value;
    }
}

public string EmpLastNameLabel
{
    get
    {
        return Label3.Text;
    }
    set
    {
        Label3.Text = value;
    }
}
public string EmpMaildIDLabel
{
    get
    {
        return Label4.Text;
    }
    set
    {
        Label4.Text = value;
    }
}
public string EmpPhoneNoLabel
{
    get
    {
        return Label5.Text;
    }
    set
    {
         Label5.Text = value;
    }
}
public string EmpIDTextBox
{
    get
    {
        return txtID.Text;
    }
    set
    {
        txtID.Text = value;
    }
}
public string EmpFirstNameTextBox
{
    get
    {
        return txtFirstName.Text;
    }
    set
    {
        txtFirstName.Text = value;
    }
}
public string EmpLastNameTextBox
{
    get
    {
        return txtLastName.Text;
    }
    set
    {
        txtLastName.Text = value;
    }
}
public string EmopMailIDTextBox
{
    get
    {
        return txtEmailID.Text;
    }
    set
    {
        txtEmailID.Text = value;
    }
}
public string EmpPhoneNoTextBox
{
    get
    {
        return txtPhoneNo.Text;
    }
    set
    {
        txtPhoneNo.Text = value;
    }
}
public string EmpButtonText
{
    get
       {
        return btnSubmit.Text;
    }
    set
    {
        btnSubmit.Text = value;
    }
}
public string SuccessLabel
{
    get
    {
        return Label6.Text;
    }
    set
    {
        Label6.Text = value;
    }
}

#endregion

Step 8

In Page Load, call the Presenter class and call BindModalView() to set the text to the ASPX label from the Model.

protected void Page_Load(object sender, EventArgs e)
{
    // Bind the data to the view from Presenter. 
    Presenter p = new Presenter(this, new MVPDemo.Model());
    p.BindModalView();
}

Step 9

In the button click event, add the following code to insert the data to the table.

protected void btnSubmit_Click(object sender, EventArgs e)
{
    // Inserting data to the database table.
    Presenter p = new Presenter(this, new MVPDemo.Model());
    p.Save();
}

Step 10

Finally, the ASPX of the result page looks like this: