Question

I’m using LINQ to Entities and I want to know how do I translate the following query to lambda expression using extension methods.

public _Deposito RegresaDepositosBancarios(int id)
        {
            return (from d in context.depositos_bancarios
                    where d.IDDeposito == id
                    select new _Deposito
                    {
                        idDeposito = d.IDDeposito,
                        cantidad = d.Monto,
                        fecha = d.FechaDeposito,
                        aplicado = d.Aplicado

                    }).Single();
        }

Notice that I’m returning a _Deposito type, how do I achieve this using extension methods?

I need something like the following:

public Persona RegresaPersonaPorNombres(string nombres, string apellidoP, string apellidoM)
        {
            var p = context.personas.Where(x => x.Nombres == nombres &&
                                               x.ApellidoP == apellidoP && 
                                               x.ApellidoM == apellidoM).FirstOrDefault();
            return p;
        }

I don’t want to return an entity type but a custom type instead

Answer 1

This is how this would be written with extension methods, but you really should not need to worry as they are both the same thing.

return context.depositos_bancarios
    .Where(d=>d.IDDeposito == id)
    .Select(d=>new _Deposito
                {
                    idDeposito = d.IDDeposito,
                    cantidad = d.Monto,
                    fecha = d.FechaDeposito,
                    aplicado = d.Aplicado

                })
    .Single();

An interesting side note: I could have used a d=> in the Where and then an e=> in the Select. Whereas, the d propogates down throughout the phrase. The only way to reset it would be to use a let phrase. This has nothing to do with the direct question, but I just thought it interesting and wanted to point it out 🙂