columns - C#Linq Group By en múltiples columnas

linq js group by multiple columns

Question

Esta pregunta ya tiene una respuesta aquí:

• Agrupar por columnas múltiples 12 respuestas

public class ConsolidatedChild
{
    public string School { get; set; }
    public string Friend { get; set; }
    public string FavoriteColor { get; set; }
    public List<Child> Children { get; set; }
}

public class Child
{
    public string School { get; set; }
    public string Name { get; set; }
    public string Address { get; set; }
    public string Friend { get; set; }
    public string Mother { get; set; }
    public string FavoriteColor { get; set; }
}

Dadas las dos clases anteriores, me gustaría usar LINQ para crear una Lista de la Lista, agrupada por las propiedades Escuela, Amigo y Color del Favorito. ¿Es esto posible con LINQ?

Por favor ignore las propiedades, el código ha sido escrito solo para ayudar con la pregunta.

Answer 1

Dada una lista:

var list = new List<Child>()
                {
                    new Child()
                        {School = "School1", FavoriteColor = "blue", Friend = "Bob", Name = "John"},
                    new Child()
                        {School = "School2", FavoriteColor = "blue", Friend = "Bob", Name = "Pete"},
                    new Child()
                        {School = "School1", FavoriteColor = "blue", Friend = "Bob", Name = "Fred"},
                    new Child()
                        {School = "School2", FavoriteColor = "blue", Friend = "Fred", Name = "Bob"},
                };

La consulta se vería así:

var newList = list.GroupBy(x => new {x.School, x.Friend, x.FavoriteColor})
                    .Select(y => new ConsolidatedChild()
                                        {
                                            FavoriteColor = y.Key.FavoriteColor,
                                            Friend = y.Key.Friend,
                                            School = y.Key.School,
                                            Children = y.ToList()
                                        }
                    );

Código de prueba:

foreach(var item in newList)
{
    Console.WriteLine("School: {0} FavouriteColor: {1} Friend: {2}", item.School,item.FavoriteColor,item.Friend);
    foreach(var child in item.Children)
    {
        Console.WriteLine("/t Name: {0}", child.Name);
    }
}

Resultado:

School: School1 FavouriteColor: blue Friend: Bob
         Name: John
         Name: Fred
School: School2 FavouriteColor: blue Friend: Bob
         Name: Pete
School: School2 FavouriteColor: blue Friend: Fred
         Name: Bob

Answer 2

Fácil:

var consolidatedChildren =
    from c in children
    group c by new
    {
        c.School,
        c.Friend,
        c.FavoriteColor,
    } into gcs
    select new ConsolidatedChild()
    {
        School = gcs.Key.School,
        Friend = gcs.Key.Friend,
        FavoriteColor = gcs.Key.FavoriteColor,
        Children = gcs.ToList(),
    };