RubroFormulario.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class RubroFormulario : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

        if (!Page.IsPostBack)
        {
            cargarRubros(Request.QueryString["id"]);
            if (Request.QueryString["id"] == null)
            {
                titulo.InnerHtml = "Nuevo Rubro";
            }
            else
            {
                titulo.InnerHtml = "Editar Rubro";

                PrecargarDatos(Int32.Parse(Request.QueryString["id"]));
            }

        }
    }

    private void PrecargarDatos(int id)
    {
        try
        {
            using (var context = new PedidosDataContext())
            {
                var temp = (from ru in context.Rubro where ru.id_rubro == Convert.ToInt32(Request.QueryString["id"]) select ru).Single();
                txtCodigo.Text = temp.codigo;
                txtDenominacion.Text = temp.denominacion;

                if (temp.id_rubroPrimario == null)
                {
                    ddlRubroPri.SelectedValue = "-1";
                }
                else
                {
                    ddlRubroPri.SelectedValue = Convert.ToString(temp.id_rubroPrimario);
                }

            }
        }
        catch (Exception)
        {

            throw;
        }
    }
    private void cargarRubros(string idModificar)
    {
        try
        {
            using (var context = new PedidosDataContext())
            {
                List<Rubro> ListaRubro = new List<Rubro>();
                if (idModificar == null)
                {
                    ListaRubro = (from iR in context.Rubro select iR).ToList();
                }
                else
                {
                    ListaRubro = (from iR in context.Rubro where iR.id_rubro.ToString() != idModificar select iR).ToList();
                }

                Rubro ir = new Rubro();
                ir.id_rubro = -1;
                ir.denominacion = "SIN RUBRO";
                ListaRubro.Add(ir);
                ddlRubroPri.DataSource = ListaRubro;
                ddlRubroPri.DataValueField = "id_rubro";
                ddlRubroPri.DataTextField = "denominacion";
                ddlRubroPri.SelectedValue = "-1";
                ddlRubroPri.DataBind();

            }
        }
        catch (Exception)
        {

            throw;
        }
    }

    protected void btnGuardar_Click(object sender, EventArgs e)
    {
        PedidosDataContext db = new PedidosDataContext();

        if (Request.QueryString["id"] == null)
        {
            try
            {
                Rubro ru = new Rubro();
                ru.codigo = txtCodigo.Text;
                ru.denominacion = txtDenominacion.Text;
                db.Rubro.InsertOnSubmit(ru);
                if (ddlRubroPri.SelectedValue == "-1")
                {
                    ru.id_rubroPrimario = null;
                }
                else
                {
                    ru.id_rubroPrimario = Convert.ToInt32(ddlRubroPri.SelectedValue);
                }
                db.SubmitChanges();

                Response.Redirect("Rubros.aspx");
            }
            catch (Exception msjError)
            {
                try
                {
                    var errorNumber = ((System.Data.SqlClient.SqlException)msjError).Number;
                    if (errorNumber == 2601)
                    {
                        lblError.Visible = true;
                        lblError.Text = "El código de rubro ya está en uso.";
                    }
                    else
                    {
                        // error desconocido
                        lblError.Visible = true;
                        lblError.Text = "Ocurrió un error al guardar el rubro.";
                    }
                }
                catch (Exception ex)
                {
                    // error desconocido
                    lblError.Visible = true;
                    lblError.Text = "Ocurrió un error al guardar el rubro.";
                }

            }

        }
        else
        {

            try
            {
                var temp = (from ru in db.Rubro where ru.id_rubro == Convert.ToInt32(Request.QueryString["id"]) select ru).Single();

                temp.codigo = txtCodigo.Text;
                temp.denominacion = txtDenominacion.Text;
                if (ddlRubroPri.SelectedValue == "-1")
                {
                    temp.id_rubroPrimario = null;
                }
                else
                {
                    temp.id_rubroPrimario = Int32.Parse(ddlRubroPri.SelectedValue);
                }

                db.SubmitChanges();

                Response.Redirect("Rubros.aspx");
            }
            catch (Exception msjError)
            {
                try
                {
                    var errorNumber = ((System.Data.SqlClient.SqlException)msjError).Number;
                    if (errorNumber == 2601)
                    {
                        lblError.Visible = true;
                        lblError.Text = "El código de rubro ya está en uso.";
                    }
                    else
                    {
                        // error desconocido
                        lblError.Visible = true;
                        lblError.Text = "Ocurrió un error al guardar el rubro.";
                    }
                }
                catch (Exception ex)
                {
                    // error desconocido
                    lblError.Visible = true;
                    lblError.Text = "Ocurrió un error al guardar el rubro.";
                }

            }

        }

    }

    protected void btnCancelar_Click(object sender, EventArgs e)
    {
        Response.Redirect("Rubros.aspx");
    }
}