Can't transform Linq to IEnumerable

Question

I have this method on my DAL class:

public IEnumerable<Pedidos> Pedidos_Listar()
    {
        using (var context = new OhmioEntities())
        {              
            var _ped = 
                from Pedidos in context.Pedidos
                where Pedidos.ID_Cliente == 1
                select new {Pedidos.ID_Pedido, Pedidos.Fecha, Pedidos.Clientes};
            return _ped.ToList();
        }
    }        

And VS give this error:

    Error   3   No se puede convertir implícitamente el 
tipo 'System.Collections.Generic.List<AnonymousType#1>' 
en 'System.Collections.Generic.IEnumerable<Ohmio.ModelLayer.Pedidos>'. 
Ya existe una conversión explícita (compruebe si le falta una conversión)

What i'm I doing wrong here?Thanks

EDIT More info: Pedidos is defined as POCOs db class So This work just fine:

public IEnumerable<Pedidos> Pedidos_Listar()
        {
            using (var context = new OhmioEntities())
            {
                return context.Pedidos.ToList();
            }
        }       

But i need to use linq to select just some field and a where clause. When I try this as suggested:

public IEnumerable<Pedidos> Pedidos_Listar()
        {
            using (var context = new OhmioEntities())
            {              
                var _ped = 
                    from Pedidos in context.Pedidos
                    where Pedidos.ID_Cliente == 1
                    select new Pedidos {Pedidos.ID_Pedido, Pedidos.Fecha, Pedidos.Clientes};
                return _ped.ToList();
            }
        }        

I get this error:

    Can't inicialize type 'Ohmio.ModelLayer.Pedidos' with a colection inicializer because 
don't implement 'System.Collections.IEnumerable' (Manual translate)

I'm i missing something here? Thanks!

Answer 1

You're not returning the type you said you would. You're returning an anonymous type. Fix this by projecting into the known type:

public IEnumerable<Pedidos> Pedidos_Listar()
    {
        using (var context = new OhmioEntities())
        {              
            var _ped = 
                from Pedidos in context.Pedidos
                where Pedidos.ID_Cliente == 1
                select new Pedidos {Id = Pedidos.ID_Pedido, Fecha = Pedidos.Fecha, Clientes = Pedidos.Clientes};
            return _ped.ToList();
        }
    }  

Or if you don't need the projection and are returning the EF model directly:

public IEnumerable<Pedidos> Pedidos_Listar()
    {
        using (var context = new OhmioEntities())
        {              
            var _ped = 
                from Pedidos in context.Pedidos
                where Pedidos.ID_Cliente == 1
                select Pedidos;
            return _ped.ToList();
        }
    }  

Or simply:

public IEnumerable<Pedidos> Pedidos_Listar()
    {
        using (var context = new OhmioEntities())
        {              
            return context.Pedidos.Where(p => p.ID_Cliente == 1);
        }
    }

Answer 2

You are creating a list of anonymous objects.If you want a strongly-typed collection change your code like this:

 var _ped = from p in context.Pedidos
            where p.ID_Cliente == 1
            select new Pedidos 
            {
                ID_Pedido = p.ID_Pedido, 
                Fecha = p.Fecha, 
                Clientes = p.Clientes
            };

Answer 3

I think you are looking for this:

select Pedidos;

Instead of this:

select new {Pedidos.ID_Pedido, Pedidos.Fecha, Pedidos.Clientes};

---

If this is Linq-to-entites, you can't project to an entity class, so this wouldn't work:

select new Pedidos { ... } 

However, you can project to a new class like

select new PedidosCustomClass { ... } 

Answer 4

Your select is selecting a new anonymous type, but you're trying to return that anonymous type as instances of Pedidos. You need to change your select to create instances of Pedidos, instead.

Answer 5

You are creating a list of anonymous objects and then trying to return it as list of Pedidos. the compiler doesn't know how to do the casting. You can either change it to:

public IEnumerable<Pedidos> Pedidos_Listar()
{
    using (var context = new OhmioEntities())
    {              
        var _ped = 
            from Pedidos in context.Pedidos
            where Pedidos.ID_Cliente == 1
            select new Pedidos;
        return _ped.ToList();
    }
}        

Or you will have to do the maping/casting yourself. Something like this will work:

public IEnumerable<Pedidos> Pedidos_Listar()
{
    using (var context = new OhmioEntities())
    {              
        var _ped = 
            from P in context.Pedidos
            where P.ID_Cliente == 1
            select new Pedidos { ID_Pedido = P.ID_Pedido,
                                 Fecha = P.Fecha,
                                 Clientes = P.Clientes};
        return _ped.ToList();
    }
}        

Answer 6

You're attempting to return an collection of anonymous objects.

You'll need to name your object in your select to Pedidos:

select new Pedidos { ID_Pedido = Pedidos.Id_Pedido, 
                     Fecha     = Pedidos.Fecha, 
                     Clientes  = Pedidos.Clientes };

Answer 7

Cause of the original error you got already explained by @Selman22. But the solution causes another error because you can't create mapped entity (your POCOs db class) in LINQ-to-entity query. To workaround this, try to initialize the entity in client side (outside LINQ-to-entity query) :

public IEnumerable<Pedidos> Pedidos_Listar()
{
    using (var context = new OhmioEntities())
    {              
        var _ped = 
            (   
                from Pedidos in context.Pedidos
                where Pedidos.ID_Cliente == 1
                select new {Pedidos.ID_Pedido, Pedidos.Fecha, Pedidos.Clientes}
            ).ToList();
        return _ped.Select(o => new Pedidos 
                                {
                                    ID_Pedido = p.ID_Pedido, 
                                    Fecha = p.Fecha, 
                                    Clientes = p.Clientes
                                });
    }
}

Answer 8

Why do you want to instanciate new Pedidos? Try simply this:

public IEnumerable<Pedidos> Pedidos_Listar()
{
    using (var context = new OhmioEntities())
    {              
        return context.Pedidos
            .Where(p => p.ID_Cliente == 1)
            .AsEnumerable();
    }
}