Hi all. I'm trying to use NHibernate.Linq with WCF RIA Services and
Silverlight. I've created a Silverlight Business Application project,
and these codes...
I have this domain class:
public class BaseDomain
{
public virtual Guid Id { get; set; }
public virtual DateTime CreatedOn { get; set; }
}
public class Sector : BaseDomain
{
public virtual string Code { get; set; }
public virtual string Name { get; set; }
}
The domain objects mapping has been set up and working fine.
The I have this DTO class:
public class SectorDto : BaseDto
{
[Key]
public virtual Guid Id { get; set; }
public virtual DateTime CreatedOn { get; set; }
public virtual string Code { get; set; }
public virtual string Name { get; set; }
public SectorDto()
{
}
public SectorDto(Sector d)
{
Id = d.Id;
CreatedOn = d.CreatedOn;
Code = d.Code;
Name = d.Name;
}
}
DTO is used to flatten the object and make sure no unnecessary
relations from being serialized and transfered over the wire.
Then I have this RIA DomainService (there are several variations of
the GetSectors() method, I'll explain later):
[EnableClientAccess]
public class OrganizationService : BaseDomainService
{
public IQueryable<SectorDto> GetSectors1()
{
return GetSession().Linq<Sector>()
.Select(x => Mapper.Map<Sector, SectorDto>(x));
}
public IQueryable<SectorDto> GetSectors2()
{
return GetSession().Linq<Sector>().ToList()
.Select(x => new SectorDto(x)).AsQueryable();
}
public IQueryable<SectorDto> GetSectors3()
{
return GetSession().Linq<Sector>().Select(x => new
SectorDto(x));
}
public IQueryable<SectorDto> GetSectors4()
{
return GetSession().Linq<Sector>().Select(x => new SectorDto()
{
Id = x.Id, CreatedOn = x.CreatedOn, Name = x.Name, Code =
x.Code });
}
}
BaseDomainService is just a parent class that provides handling for
NHibernate session. I set the session to live per web request.
Then I hook up the service to a DataGrid (Silverlight Toolkit) in a
XAML page:
var ctx = new App.Web.Services.OrganizationContext();
SectorGrid.ItemsSource = ctx.SectorDtos;
ctx.Load(s.GetSectors1Query());
When calling the various methods, I got these results:
1. Method GetSectors1() produce an exception "Load operation failed
for query 'GetSectors1'. Unable to cast object of type
NHibernate.Linq.Expressions.EntityExpression' to type
'NHibernate.Linq.Expressions.CollectionAccessExpression'.".
This is the best way that I'm trying to achive. I want to use the
AutoMapper library to automatically map the domain class to the DTO.
I'm quite positive that the problem is not from the AutoMapper since I
also get the error if I call a method from inside the anonymous method
passed into Select, eg. GetSession().Linq<Sector>().Select(x =>
CustomMap(x)).
2. Method GetSectors2() displays the data correctly in the grid, but
this defeats the purpose of using IQueryable, the call would not be
lazy evaluated.
3. Method GetSectors3() fetches the data, but only the Id and
CreatedOn which is in the parent class BaseDomain. The Code and Name
are both null.
4. Method GetSectors4() fetches the data correctly and lazily
evaluated, but I don't want to manually map my domain to DTO every
time like this!
So what gives? The results are so far away than what I expected! Any
idea on how to make this work? Any advice?
I appreciate any help, I'm nearly lost. Thank you very much.
p.s: I also posted this at
http://stackoverflow.com/questions/2339449/nhibernate-linq-wcf-ria-services-weird-error
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