Get result from Linq-to-SQL query

Question

I'm new to Linq-to-SQL and I don't what is the correct way to use results from a query in Linq. I use a function which returns data of two tables:

public IQueryable RegresaDatosCredito(int idC)
{
   var credito = from a in context.acreditados
                 where a.creditos.IDCredito == idC
                 select new
                 {
                     Monto = a.Cantidad,
                     Tasa = a.creditos.TasaInteres,
                     Plazo = a.creditos.Plazo,
                     Periodo = a.creditos.Periodo,
                     Producto = a.creditos.Producto,
                     Expediente = a.creditos.Expediente
                 };

   return credito;
}

This query will always return one row from my database. Then I want to use the result from this query and show this in different textBoxes. In other class I created a method to print this result like I mentioned above.

private void SomeMethod()
{
   try
   {
      var credito = operaciones.RegresaDatosCredito(idCred);
      text_MontoC.Text = credito.Monto;
      text_TasaC.Text = credito.Tasa;
      text_PlazoC.Text = credito.Plazo;
      text_PeriodoC.Text = credito.Periodo;
      text_ProductoC.Text = credito.Producto;
      text_ExpedienteC.Text = credito.Expediente;
   }
   catch (Exception ex)
   {
      MessageBox.Show(ex.ToString());
   }
}

But I can't access results doing something like credito.???, what is the correct way to do it?

In RegresaDatosCredito I return a IQueryable datatype because in the query I'm joining two tables using fk relationship, am I wrong?

Thanks

Answer 1

You're returning an "anonymous" datatype in the IQueryable, not a good habit since you can't access it outside of the method where it's created.

Try declaring a struct that can hold your data and return an IQueryable<CreditoStruct> instead, or even - since you're just wanting a single value - call Single() on the IQueryable to get a CreditoStruct and return that.

public CreditoStruct RegresaDatosCredito(int idC)
{
    return (from a in context.acreditados
                             where a.creditos.IDCredito == idC
                             select new CreditoStruct
                             {
                                 Monto = a.Cantidad,
                                 Tasa = a.creditos.TasaInteres,
                                 Plazo = a.creditos.Plazo,
                                 Periodo = a.creditos.Periodo,
                                 Producto = a.creditos.Producto,
                                 Expediente = a.creditos.Expediente
                             }).Single();
}

Answer 2

if You are expecting just one result use the Single Method.

var credito = (from a in context.acreditados
                             where a.creditos.IDCredito == idC
                             select new
                             {
                                 Monto = a.Cantidad,
                                 Tasa = a.creditos.TasaInteres,
                                 Plazo = a.creditos.Plazo,
                                 Periodo = a.creditos.Periodo,
                                 Producto = a.creditos.Producto,
                                 Expediente = a.creditos.Expediente
                             }).Single();

Also you should parse your result to a concrete type instead of an anounymus type

Lets say you create a class

public class Credito
{
   public decimal Monto{get;set;}
 public decimal Tasa{get;set;}
 public decimal Plazo{get;set;}
 public string Periodo{get;set;}
 public string Producto{get;set;}
 public string Expediente{get;set;}
}

and then You can Use it like this

var credito = (from a in context.acreditados
                             where a.creditos.IDCredito == idC
                             select new Credito
                             {
                                 Monto = a.Cantidad,
                                 Tasa = a.creditos.TasaInteres,
                                 Plazo = a.creditos.Plazo,
                                 Periodo = a.creditos.Periodo,
                                 Producto = a.creditos.Producto,
                                 Expediente = a.creditos.Expediente
                             }).Single();

if you want to return various of them use instead of Single, toList() and thats it.

Then define your function to return a Credito type (with Single()) or List<Credito> (with ToList())