Save data to client for later use

Question

I have a web form application where the user enters with some values to perform an analysis. It is two values item and quantity, this data is in one List<> which is used as DataSource of a GridView. They can have up to 50 items, but usually does not exceed 5 items.

Use the following code to manipulate typed valuables:

public class Analise
{
    public int Item { get; set; }
    public int Quantidade { get; set; }
    public double CustoUnitario { get; set; }
    public double CustoAnual { get; set; }
}

static List<Analise> analiseLista = new List<Analise>();


protected void btnAdicionar_Click(object sender, EventArgs e)
{
    try
    {
        lblErro.Text = "";
        //Regex para validar somente números
        Regex soNumeros = new Regex(@"^[0-9]+$");
        if (!soNumeros.IsMatch(txtItem.Text) || !soNumeros.IsMatch(txtQuantidade.Text))
        {
            lblErro.Text = "Valore devem ser numéricos";
            return;
        }

        Int32 item = Convert.ToInt32(txtitem.Text);
        Int32 quantidade = Convert.ToInt32(txtQuantidade.Text);

        using (BDEntities db = new BDEntities())
        {
            //Verifica ser item existe em TB_item 
            var itemBD = (from c in db.TB_item
                                where c.item == item
                                select new
                                {
                                    c.CUSTO_item
                                }).ToList();
            if (itemBD.Count == 0)
            {
                //Se não existir mensagem de erro
                lblErro.Text = "item: " + item + " não cadastrada!";
            }
            else
            {
                //Se existir continua o processo
                custoUnitarioitem = (Double)itemBD.FirstOrDefault().CUSTO_item;
                custoAnual = (quantidade * custoUnitarioitem);

                //Verifica se item existe na lista analiseLista
                var existeAnalise = analiseLista.Where(c => c.item.Equals(item)).FirstOrDefault();
                if (existeAnalise == null)
                {
                    //Se não existir INCLUI
                    var novo = new Analise() { item = item, Quantidade = quantidade, CustoUnitarioitem = custoUnitarioitem, CustoAnual = custoAnual };
                    analiseLista.Add(novo);
                }
                else
                {
                    //Se existir ALTERA ou EXLCUI
                    if (quantidade == 0)
                    {
                        //Se quantidade zero exclui item da analiseLista
                        analiseLista.Remove(existeAnalise);
                    }
                    else
                    {
                        //Se quantidade maior que zero e capcacidade existe em analiseLista ALTERA 
                        existeAnalise.item = item;
                        existeAnalise.Quantidade = quantidade;
                        existeAnalise.CustoUnitarioitem = custoUnitarioitem;
                        existeAnalise.CustoAnual = custoAnual;
                    }
                }
                //Atualiza o grid com os valores
                gdvAnalise.DataSource = analiseLista.OrderBy(a => a.item).ToList();
                gdvAnalise.DataBind();
                double somatorio = analiseLista.Sum(x => Convert.ToDouble(x.CustoAnual));
                txtTotal.Text = somatorio.ToString();
            }
        }
        txtitem.Text = null;
        txtQuantidade.Text = null;
        txtitem.Focus();
    }
    catch (Exception ex)
    {
        throw ex;

    }
}

Stay like this:

I need to save the contents of this List so that whenever the user enters the application they are available and are loaded in a GridView with the last analysis performed. I didn’t want a table in the comic book for this.

How you could do this using Cache or there is another option?

Or I’ll have to create a comic book table for this

Answer 1

Of course there are other options but it may be that using a table in the bank is really the best.

Think about this scenario: the user opens the page on the work computer, creates such analysis, after a while goes back to this page and the last analysis appears automatically because it was saved in the client (browser.) Then this user decides to use another browser or even another computer and nothing is remembered. Would that be intuitive for the user? That’s what you really want to implement?

If you find that the above scenario is no problem then you can search for local storage alternatives (on client) like window.localStorage, window.indexedDB or the File API. All these alternatives may not work in all types of browser.

Other alternatives involving server storage are equivalent to using a database and, worse, they may suffer from limitations such as not functioning properly when you have more than one web server (web Farms). I would suggest reconsidering and using the database instead of creating something more fragile.