c# layer development (BBL, DAL, Model, GUI)

Question

In my project I am developing in C# using windows Form Application with the pattern of development in Layers I am in doubt if this form is correct? because I’ve researched a lot about layers, but I realize that each person develops in a way.

Have the following layers:

• BBL - business rules or validations;

• DAL - for access to the bank

• GUI - for forms and part user interaction

• Model - where class models for inheritance are located.

To record a user I am developing this way:

DAL - Connection:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System;
using System.Data;
using Npgsql;

namespace DAL
{
    public class Conexao
    {
        protected NpgsqlConnection Con; // estabele a conexao
        protected NpgsqlCommand Cmd; // executar e escrever os comandos sql
        protected NpgsqlDataReader Dr; //retorna os registro das querys das consultar
        // Dados da conexao 
        private string servidor = "127.0.0.1";   
        private string porta = "5432";
        private string userBD = "postgres";
        private string senhaBD = "123";
        private string banco = "teste";
        private string connString = null;

        protected void abrirConexao()
        {

            try
            {
                connString = String.Format("Server={0};Port={1};User Id={2};Password={3};Database={4};",
                                                servidor, porta, userBD, senhaBD, banco);
                Con = new NpgsqlConnection(connString);
                Con.Open();

            }
            catch (NpgsqlException ex)
            {
                Console.WriteLine("erro ao abrir conexao" + ex.Message);
                throw new NpgsqlException(ex.Message);

            }
        }

        protected void fecharConexao()
        {
            try
            {
                Con.Close();
            }
            catch (NpgsqlException ex)
            {

                throw new NpgsqlException(ex.Message);
            }
        }        
    }
}

DAL - User

namespace DAL
{
    public class UsuarioDAL : Conexao
    {
        public void insere(UsuarioModel usuario) 
        {
            try
            {
                //Abre a conexao para insercao
                abrirConexao();
                Cmd = new NpgsqlCommand("insert into \"Cadastro\".\"Usuario\" (id) values (@id)", Con);
                Cmd.Parameters.AddWithValue("@id", usuario.id);
                Cmd.ExecuteNonQuery();
                MessageBox.Show("Usuario Inserido com Sucesso");
            }
            catch (Exception ex)
            {
                MessageBox.Show("Erro ao inserer usuario - Erro: " + ex.Message);

            }

        }
    }
}

Model - User model

only get and set and builder ...

Now in the package BBL - User should I make the validations ? create the Validate method and validate with Data Annotations and call the insert of DAL?

and in the User class I should only instantiate the User to be safer and run Validainsert?

Would those my doubts prevent me from developing in c#.

Thank you for your attention.

Answer 1

You can’t follow through.

I’ve been programming for 29 years and a few years ago, with desktop/web merging, I realized the advantage of breaking down the layers:

• DICE - No comments. It’s like you already do. (clsDados...)
• VIEW (view_web/view_desktop/view_mobile) - This is where the team separates the presentation layer. (Windows Forms)
• MODEL - Other classes (clsEmpresa, clsNotaFiscal...)
• CONTROL - Validations, Formatting functions, etc. (clsFuncoes, ...)

Think of a DECOUPLED programming model where there is no dependency between one layer and the other.

Examples 1: Avoid being in the CONTROL layer and from there refer to objects in the VIEW layer:

public static void fRetiraAcentuacao(string texto)
{ 
   form2.txtCNPJ.Text = texto.Replace()... ; 
}

I find it more elegant and decoupled like this:

public static void fRetiraAcentuacao(string texto, ref TextBox txt)
{ 
   txt.Text = texto.Replace()... ; 
}

Example2: I cannot be in Form1 and call:

**form2**.TextBox.Text = string.Empty;

It’s how I do and help with programming within development teams.

Another thing: always remember that another programmer needs to maintain your code. Comment on what is not obvious.

Eager to see how others do!