After sitting on this for awhile, I came back to it and found a
quick(ish) solution, although it involved modifying the Abstract Form
Helper source and recompiling monorail framework. I added a try/catch
InvalidCastException block in the ReflectionValueGetter.GetValue
method, so that the final code looked like this:
public override object GetValue(object instance)
{
try
{
try
{
return
propInfo.GetValue(instance, null);
}
catch (InvalidCastException)
{
propInfo =
propInfo.ReflectedType.BaseType.GetProperty(Name);
return
propInfo.GetValue(instance, null);
}
}
catch (TargetException)
{
var tempProp =
instance.GetType().GetProperty(Name);
if (tempProp == null)
{
throw;
}
return tempProp.GetValue(instance,
null);
}
}
After recompiling, voila! No more invalid cast errors. Just thought I
would share the solution here if anyone was interested.
Thanks,
Brian
On Jul 31, 2:04 pm, bluesliverx <[email protected]> wrote:
> Dan,
>
> Thanks for the reply! I think you are exactly right with this. I've
> dug a little more in the last couple of days and found it only happens
> when I have another object with a Section object attached to it (in a
> belongsto) that is loaded, and then the other section object is
> loaded. The problem is, in the controller I am loading two
> collections: the model with the attached Section object called
> Application, and the collection of all Section objects. These are
> lazy loaded by the way. When they are used with the FormHelper in the
> view is when I actually receive the error. Also, neither of these
> collections use a type hierarchy at all.
>
> I also investigated further into the source code ofmonoand found
> that the types involved were:
> Cannot cast from source type 'Models.Section' to destination type
> 'Castle.Proxies.SectionProxy', so it looks like the Proxy was already
> used/loaded and it is trying to cast to that I believe, or vice versa
> I guess.
>
> So my questions:
> 1) How do I clear the session in a way that still allows my lazy
> loaded collections to load fine in the view? (I also couldn't find how
> to easily clear the session besides using a new one, if you have a
> quick tip on that, that would be great)
> 2) Why does this error only occur inmonoand not in MS.NET? I know
> you probably don't know this one off the top of your head. But do you
> think this is a bug inmonoI should investigate and try to report, or
> something to do with the internals of ActiveRecord/NHibernate?
>
> Thanks so much!
> -Brian
>
> On Jul 30, 5:26 pm, Daniel Quirk <[email protected]> wrote:
>
>
>
> > Brian,
>
> > In the stacktrace you'll notice DifferentTypeOperationState, this
> > suggests the list contains more than one type of object. The exception
> > is therefore probably being caused by a section object being in the
> > cache due to another query having already been run in this request,
> > and so Nhibernate returns that object instead of fetching it again,
> > however this object is somehow a different type, ( base say, if you
> > were using tipe hierarchy) , and so cannot be cast. Try clearing the
> > session before you run your sections query and let me know how you get
> > on.
>
> > Cheers,
>
> > Dan
>
> > On Jul 30, 12:19 am, bluesliverx <[email protected]> wrote:
>
> > > I've been butting my head against this problem for months now, and I
> > > know that there aren't a lot of MonoRail +Monousers out there, but I
> > > thought I would see if anyone has any ideas.
>
> > > I'm using a pretty recent trunk version of MonoRail+ActiveRecord on
> > >mono, and I've run into this onmono2.4, 2.6, and now even the daily
> > > tarball from yesterday (2.7 basically). It works fine on MS.NET. I
> > > receive a System.InvalidCastException when running the form helper
> > > select method on some activerecord objects. The objects are very
> > > simple (basically an Id and a Name - shown below), but in certain
> > > cases (and the cases seem random, but they are consistently on the
> > > same objects) it is throwing this exception onmono.
>
> > > Please help me! I feel like I'm missing something and just can't find
> > > it.
>
> > > Here is the full stack trace:
>
> > > System.InvalidCastException: Cannot cast from source type to
> > > destination type.
> > > at
> > > System.Reflection.MonoProperty.GetterAdapterFrame[SectionProxy,Int32]
> > > (System.Reflection.Getter`2 getter, System.Object obj) [0x00000] in /
> > > root/mono/build/mono-20100729/mcs/class/corlib/System.Reflection/
> > > MonoProperty.cs:245
> > > at System.Reflection.MonoProperty.GetValue (System.Object obj,
> > > System.Object[] index) [0x00070] in /tmp/mono/build/mono-20100729/mcs/
> > > class/corlib/System.Reflection/MonoProperty.cs:307
> > > at Castle.MonoRail.Framework.Helpers.AbstractFormRelatedHelper
> > > +ReflectionValueGetter.GetValue (System.Object instance) [0x00000] in
> > > <filename unknown>:0
> > > at
> > > Castle.MonoRail.Framework.Helpers.DifferentTypeOperationState.CreateItemRep
> > > resentation
> > > (System.Object current) [0x00000] in <filename unknown>:0
> > > at Castle.MonoRail.Framework.Helpers.OperationState.get_Current ()
> > > [0x00000] in <filename unknown>:0
> > > at Castle.MonoRail.Framework.Helpers.FormHelper.GenerateSelect
> > > (System.String target, System.Object selectedValue, IEnumerable
> > > dataSource, IDictionary attributes) [0x00000] in <filename unknown>:0
> > > at Castle.MonoRail.Framework.Helpers.FormHelper.Select
> > > (System.String target, System.Object selectedValue, IEnumerable
> > > dataSource, IDictionary attributes) [0x00000] in <filename unknown>:0
> > > at CompiledViews.myviewname.Render () [0x00000] in <filename
> > > unknown>:0
> > > at Castle.MonoRail.Views.AspView.AspViewBase.Process () [0x00000] in
> > > <filename unknown>:0
> > > at Castle.MonoRail.Views.AspView.AspViewBase.GetContentViewContent
> > > () [0x00000] in <filename unknown>:0
> > > at Castle.MonoRail.Views.AspView.AspViewBase.Process () [0x00000] in
> > > <filename unknown>:0
> > > at Castle.MonoRail.Views.AspView.AspViewBase.GetContentViewContent
> > > () [0x00000] in <filename unknown>:0
> > > at Castle.MonoRail.Views.AspView.AspViewBase.Process () [0x00000] in
> > > <filename unknown>:0
> > > at Castle.MonoRail.Views.AspView.AspViewEngine.Process
> > > (System.String templateName, System.IO.TextWriter output,
> > > IEngineContext context, IController controller, IControllerContext
> > > controllerContext) [0x00000] in <filename unknown>:0
> > > at
> > > Castle.MonoRail.Framework.Services.DefaultViewEngineManager.Process
> > > (System.String templateName, System.IO.TextWriter output,
> > > IEngineContext context, IController controller, IControllerContext
> > > controllerContext) [0x00000] in <filename unknown>:0
> > > at Castle.MonoRail.Framework.Controller.ProcessView () [0x00000] in
> > > <filename unknown>:0
> > > at mycontrollername.ProcessView () [0x00000] in <filename unknown>:
> > > 0
> > > at Castle.MonoRail.Framework.Controller.RunActionAndRenderView ()
> > > [0x00000] in <filename unknown>:0
>
> > > Here is the Section model that the SectionProxy is being generated
> > > from:
>
> > > [ActiveRecord("sections",Lazy=true)]
> > > public class Section : ActiveRecordValidationBase<Section> {
> > > // Private variables
> > > private int id;
> > > private string name;
>
> > > [PrimaryKey("id")]
> > > public virtual int Id {
> > > get { return id; }
> > > set { id = value; }
> > > }
>
> > > [Property("name", NotNull=true)]
> > > [ValidateNonEmpty("Please enter a name for the section")]
> > > public virtual string Name {
> > > get { return name; }
> > > set { name = value.Trim(); }
> > > }
> > > }
>
> > > And finally here is my view code generating the select:
>
> > > <aspView:properties>
> > > <%
> > > IList<Section> sections = null;
> > > %>
> > > </aspView:properties>
>
> > > <p><%=Helpers.Form.LabelFor("selectedSection", "Section:")%> <
> > > %=Helpers.Form.Select("selectedSection", sections,
> > > Helpers.Dict.CreateDict("text=Name", "value=Id",
> > > "firstoption=",
> > > "firstoptionvalue=0"))%></p>
>
> > > I have tried setting the selected value on the FormHelper.Select
> > > method, but am having no luck whatsoever in finding what exactly is
> > > going on. This view code is designed to have none selected (ie
> > > selectedSection is a made up target which doesn't exist as an object),
> > > but I have used other complex objects which try to set the properties
> > > appropriately and sometimes succeed and sometimes throw exactly the
> > > same error.
> > > I should reiterate I think - it is consistently thrown on the same
> > > objects (ie the object id is 17), but works fine for other values/
> > > selections.
>
> > > Thanks so much for all of your help!
> > > -Brian
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