C# 如何使用具有显式接口属性的 linq？

Question

i have one class with two inheritance interfaces and yours attributes are explicits because both have some equals attributes, so, i need use LINQ with this class, but i can't access the explicits attributes when i use "select new Foo" ... look the case:

public class QuestaoMontaProva : IQuestao, IExercicio
{

    public int Discordo { get; set; }
    public int Rever { get; set; }
    public int Anotacao { get; set; }
    public int Realizada { set; get; }
    public int Ativo { set; get; }


    int IQuestao.Id { get; set; }

    string IQuestao.EnunciadoQuestao { get; set; }

    string IQuestao.ExercicioTipo { get; set; }

....

and my LINQ :

var flags = (from b in dt.AsEnumerable()

                             select new QuestaoMontaProva
                             {
                                 IdQuestao = Convert.ToInt32(b["ID_QUESTAO"]), // i can't access this
                                 IdTipoExercicio = Convert.ToInt32(b["ID_TIPOEXERCICIO"]),// i can't access this
                                 Discordo = Convert.ToInt32(b["DISCORDO"]),
                                 Rever = Convert.ToInt32(b["REVER"]),
                                 Anotacao = Convert.ToInt32(b["ANOTACAO"]),
                                 Realizada = Convert.ToInt32(b["REALIZADA"]),
                                 Correta = Convert.ToInt32(b["CORRETA"]),
                                 Ativo = Convert.ToInt32(b["ATIVO"])
                             }).ToList();

Answer 1

If possible, implement the interfaces implicitly instead of explicitly, as Servy suggested .

If that won't work for you, use method syntax for this portion instead of query syntax, so that you can include a multi-line delegate instead of a single-expression one. This lets you cast to access the hidden properties.

var flags = dt.AsEnumerable().Select(b =>
{
    var q = new QuestaoMontaProva
    {
        Discordo = Convert.ToInt32(b["DISCORDO"]),
        Rever = Convert.ToInt32(b["REVER"]),
        Anotacao = Convert.ToInt32(b["ANOTACAO"]),
        Realizada = Convert.ToInt32(b["REALIZADA"]),
        Correta = Convert.ToInt32(b["CORRETA"]),
        Ativo = Convert.ToInt32(b["ATIVO"])
    };
    var iq = (IQuestao)q;
    iq.Id = Convert.ToInt32(b["ID_QUESTAO"]);
    iq.ExercicioTipo = Convert.ToInt32(b["ID_TIPOEXERCICIO"]);
    return q;
}).ToList();

Answer 2

You could just add a backing field for the explicit interface implementation. This way you are implementing an interface and are able to get/set values.

var query = from i in items
            select new QuestaoMontaProva
            {
                Id = 1,
                IQuestaoId = 2,
                IExercicioId = 2
            };

public interface IQuestao
{
    int Id { get; set; }
}

public interface IExercicio
{
    int Id { get; set; }
}

public class QuestaoMontaProva : IQuestao, IExercicio
{
    public int Id { get; set; }
    public int IQuestaoId { get; set; }
    public int IQuestao.Id
    {
        get
        {
            return IQuestaoId;
        }
        set
        {
            IQuestaoId = value;
        }
    }

    public int IExercicioId { get; set; }
    public int IExercicio.Id
    {
        get
        {
            return IExercicioId;
        }
        set
        {
            IExercicioId = value;
        }
    }
}

Answer 3

i found one way, i just create one proxy to use the attributes of the interfaces in my class, look:

public class QuestaoMontaProva : IQuestao, IExercicio {

    public int Discordo { get; set; }
    public int Rever { get; set; }
    public int Anotacao { get; set; }
    public int Realizada { set; get; }
    public int Ativo { set; get; }
    public int IdEspecialidade { get; set; }
    public string NomeEspecialidade { set; get; }
    public string DescricaoAlternativa { set; get; }
    public int IdQuestao { get { return (this as IQuestao).Id; } set { (this as IQuestao).Id = value; } }
    public int IdTipoExercicio { get { return (this as IQuestao).IdTipoExercicio; } set { (this as IQuestao).IdTipoExercicio = value; } }
    public int Correta { get { return (this as IQuestao).Correta; } set { (this as IQuestao).Correta = value; } }
    public int Ano { get { return (this as IExercicio).Ano; } set { (this as IExercicio).Ano = value; } }
    public int IdExercicio { get { return (this as IExercicio).Id; } set { (this as IExercicio).Id = value; } }
    public string NomeExercicio { get { return (this as IExercicio).Nome; } set { (this as IExercicio).Nome = value; } }
    public string Regiao { get { return (this as IExercicio).txtRegiao; } set { (this as IExercicio).txtRegiao = value; } }
    public string EnunciadoQuestao { get { return (this as IQuestao).EnunciadoQuestao; } set { (this as IQuestao).EnunciadoQuestao = value; } }
    public string GuidQuestao { get { return (this as IQuestao).GuidQuestao; } set { (this as IQuestao).GuidQuestao = value; } }


    public int IQuestao.Id { get; set; }

    string IQuestao.EnunciadoQuestao { get; set; }

    string IQuestao.ExercicioTipo { get; set; }

    List<Especialidade> IQuestao.Especialidades { get; set; }

... }

this solved my problem!!! i hope it helps all...