Lambda or Linq brings me all the fields and not only those of expression

Question

Just for learning even, understand the section. I did a lambda of a bank with only 6 fields, like this:

 public List<LiberacaoDTO> getAutoriza(int idorcamento)
    {
        var lista = contexto.Liberacoes
       .Where(m => m.IdOrcamento == idorcamento)
       .Select(m => new LiberacaoDTO
       {
           TipoVenda = m.TipoVenda,
           Juros = m.Juros != 0 ? m.Juros : 0,
           Entrada = m.Entrada != 0 ? m.Entrada : 0,
           MaxComi = m.MaxComi,
           Cliente = m.Cliente,
           Filial = m.Filial
       })
       .ToList();

        return lista;
    }

When the service returns, it brings all the fields. Only those listed in the expression, with value, the others have null or 0. But why all fields and not only those listed in the expression? Below the call of my service:

public class LiberacaoController : ApiController
    {
        AutorizadorContext contexto = new AutorizadorContext();
        PedidoLiberacao liberacao = new PedidoLiberacao();

        [AcceptVerbs("Get")]
        public IEnumerable<LiberacaoDTO> getLiberacao()
        {
            return liberacao.getAutoriza(1000012093).AsEnumerable().ToList();
         }
    }

Answer 1

Fields you did not specify in . Select are initialized with their default value. For example, all fields int will have the value 0, all fields string null and all fields DateTime will have the value 1/1/0001 12:00:00 AM.

This is because . Select creates a new instance of the object LiberacaoDTO.

If you want it to return only the . Select fields you can use an anonymous object in . Select:

.Select(m => new 
 {
     TipoVenda = m.TipoVenda,
     Juros = m.Juros != 0 ? m.Juros : 0,
     Entrada = m.Entrada != 0 ? m.Entrada : 0,
     MaxComi = m.MaxComi,
     Cliente = m.Cliente,
     Filial = m.Filial
 })

The problem with this approach is that you will miss some of the typing.