handle this object datasource on reporting services

问题

If I had a class defined with this attributes

public class GestionesDataSet
{
    public DateTime GestionInicio { get; set; }
    public DateTime GestionFin { get; set; }
    public Nullable<DateTime> LlamadaInicio { get; set; }
    public Nullable<DateTime> LlamadaFin { get; set; }
    public string Login { get; set; }
    public string Tipificacion { get; set; }
    public List<CamposGestion> campoValor { get; set; } 
}   

And the class called CamposGestion is defined like this

public class CamposGestion
{
    public string Nombre { get; set; }
    public string Valor { get; set; }
}

How can I Defined a report where I can use the field that refers to the list of the other elements?

I tried to used one dataset where I can set this linq as object data source

     var gestiones = (from G in db.Gestion
                         where
                         G.IDTipificacion == idTipificacion
                         && (from T in db.Tipificacion where T.IdTipificacion == G.IDTipificacion select T.Servicio.IDServicio).AsEnumerable().Contains(idServicio)
                         select G).AsEnumerable().Select(xx => new GestionesDataSet()
                         {
                             GestionInicio = xx.HoraInicio,
                             GestionFin = xx.HoraFin,
                             @Tipificacion = ((from T in db.Tipificacion select T).Where(x => x.IdTipificacion == xx.IDTipificacion).Count() > 0 ?
                                              (from T in db.Tipificacion where T.IdTipificacion == xx.IDTipificacion select T.Nombre).FirstOrDefault() : ""),
                             LlamadaInicio = xx.Llamada.HoraInicio,
                             LlamadaFin = xx.Llamada.HoraFin,
                             Login = xx.Llamada.Sesion.Usuario.Nombre,
                             campoValor = xx.CampoValor.Select(aux  => new CamposGestion() { 
                                                Nombre = aux.ConfiguracionCampo.Campo.Nombre,
                                                Valor = aux.Valor
                                        }).ToList()
                         }).ToList();

But what I want to see the report the field that contains the List show's an error like this

Any help would be appreciate.

回答1:

I would rewrite the query like this:

var gestiones = 
    from xx in db.Gestion
    where
    xx.IDTipificacion == idTipificacion
    && (from T in db.Tipificacion 
        where T.IdTipificacion == xx.IDTipificacion select T.Servicio.IDServicio).AsEnumerable().Contains(idServicio)
    select new GestionesDataSet()
    {
        GestionInicio = xx.HoraInicio,
        GestionFin = xx.HoraFin,
        @Tipificacion = (from T in db.Tipificacion where T.IdTipificacion == xx.IDTipificacion select T.Nombre).FirstOrDefault() ?? "",
        LlamadaInicio = xx.Llamada.HoraInicio,
        LlamadaFin = xx.Llamada.HoraFin,
        Login = xx.Llamada.Sesion.Usuario.Nombre,
        campoValor = xx.CampoValor.Select(aux => new CamposGestion()
        {
            Nombre = aux.ConfiguracionCampo.Campo.Nombre,
            Valor = aux.Valor
        }).ToList()
    }).ToList();

When you call a projection (Select) after the AsEnumerable was called, LINQ will try to get the navigation objects first from the already loaded ones. If no object is loaded, then will execute a select SQL command for each navigation property used in the projection. If the [DeferredLoadingEnabled][1] property is set to false it won't execute any query and if no object is loaded already (they can be loaded "apriori" with [LoadWith][2]) it will give a NullReferenceException. So, in some situations, calling AsEnumerable might hurt performance. All these things are not valid when AsEnumerable is used in the where parts.

For giving a default value, when no Tipificacion doesn't exist, it can be used the null-coalescing operator, from C#, instead of using the Count method, which creates an extra lookup on the the table.

Now.. to your problem.

SSRS doesn't support binding to a list of items. The column campoValor tries to bind to a list of objects, which is not allowed. So either you create a subreport (there is a section which describes this) or you flatten your data (having the all the properties on one single object) and then use the HideDuplicates property

来源：https://stackoverflow.com/questions/9637818/handle-this-object-datasource-on-reporting-services