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(),
};