[C#] LINQ : “포함”및 Lambda 쿼리

정확히 무엇을 찾고 있는지 잘 모르겠지만이 프로그램은 다음과 같습니다.

    public class Building
    {
        public enum StatusType
        {
            open,
            closed,
            weird,
        };

        public string Name { get; set; }
        public StatusType Status { get; set; }
    }

    public static List <Building> buildingList = new List<Building> ()
    {
        new Building () { Name = "one", Status = Building.StatusType.open },
        new Building () { Name = "two", Status = Building.StatusType.closed },
        new Building () { Name = "three", Status = Building.StatusType.weird },

        new Building () { Name = "four", Status = Building.StatusType.open },
        new Building () { Name = "five", Status = Building.StatusType.closed },
        new Building () { Name = "six", Status = Building.StatusType.weird },
    };

    static void Main (string [] args)
    {
        var statusList = new List<Building.StatusType> () { Building.StatusType.open, Building.StatusType.closed };

        var q = from building in buildingList
                where statusList.Contains (building.Status)
                select building;

        foreach ( var b in q )
            Console.WriteLine ("{0}: {1}", b.Name, b.Status);
    }

예상 출력을 생성합니다.

one: open
two: closed
four: open
five: closed

이 프로그램은 열거 형의 문자열 표현을 비교하고 동일한 출력을 생성합니다.

    public class Building
    {
        public enum StatusType
        {
            open,
            closed,
            weird,
        };

        public string Name { get; set; }
        public string Status { get; set; }
    }

    public static List <Building> buildingList = new List<Building> ()
    {
        new Building () { Name = "one", Status = "open" },
        new Building () { Name = "two", Status = "closed" },
        new Building () { Name = "three", Status = "weird" },

        new Building () { Name = "four", Status = "open" },
        new Building () { Name = "five", Status = "closed" },
        new Building () { Name = "six", Status = "weird" },
    };

    static void Main (string [] args)
    {
        var statusList = new List<Building.StatusType> () { Building.StatusType.open, Building.StatusType.closed };
        var statusStringList = statusList.ConvertAll <string> (st => st.ToString ());

        var q = from building in buildingList
                where statusStringList.Contains (building.Status)
                select building;

        foreach ( var b in q )
            Console.WriteLine ("{0}: {1}", b.Name, b.Status);

        Console.ReadKey ();
    }

한 IEnumerable을 다른 IEnumerable로 변환하기 위해이 확장 방법을 만들었지 만 이것이 얼마나 효율적인지 잘 모르겠습니다. 그냥 무대 뒤에서 목록을 만들 수 있습니다.

public static IEnumerable <TResult> ConvertEach (IEnumerable <TSource> sources, Func <TSource,TResult> convert)
{
    foreach ( TSource source in sources )
        yield return convert (source);
}

그런 다음 where 절을 다음과 같이 변경할 수 있습니다.

where statusList.ConvertEach <string> (status => status.GetCharValue()).
    Contains (v.Status)

와 List<string>함께 만들기를 건너 뛰십시오ConvertAll ()시작 부분에서 .

답변

public static IQueryable<Building> WithStatus(this IQueryable<Building> qry,
IList<BuildingStatuses> buildingStatus)
{
    return from v in qry
           where ContainsStatus(v.Status)
           select v;
}


private bool ContainsStatus(v.Status)
{
    foreach(Enum value in Enum.GetValues(typeof(buildingStatus)))
    {
        If v.Status == value.GetCharValue();
            return true;
    }

    return false;
}