DevForce Community Forum : Async Navigation in SL with PropertyChanged events http://www.ideablade.com/forum/ This is an XML content feed of; DevForce Community Forum : DevForce 2010 : Async Navigation in SL with PropertyChanged events Wed, 29 Jul 2026 15:57:19 -700 Fri, 21 Jan 2011 09:35:57 -700 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 9.69 360 www.ideablade.com/forum/RSS_post_feed.asp?TID=2247 DevForce Community Forum http://www.ideablade.com/forum/forum_images/IdeaBlade_logo_tm.png http://www.ideablade.com/forum/ Async Navigation in SL with PropertyChanged events : Ah sorry I didn't notice... http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=9736#9736 Author: tj62
Subject: 2247
Posted: 21-Jan-2011 at 9:35am

Ah sorry I didn't notice the scroll bar: Here is the total copy/paste from that dialog:
 
Microsoft JScript runtime error: Unhandled Error in Silverlight Application Collection was modified; enumeration operation may not execute.   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at System.Collections.Generic.List`1.Enumerator.MoveNext()
   at System.Linq.Enumerable.WhereListIterator`1.MoveNext()
   at IdeaBlade.Core.EnumerableFns.ForEach[T](IEnumerable`1 items, Action`1 action)
   at IdeaBlade.EntityModel.PendingEntityMap.Update(EntityWrapper pendingWrapper, EntityWrapper realWrapper)
   at IdeaBlade.EntityModel.ScalarEntityReference`1.InformPendingEntityOfRealEntity(EntityWrapper realEntity)
   at IdeaBlade.EntityModel.ScalarEntityReference`1.QueryCallback(EntityQueryOperation op)
   at IdeaBlade.EntityModel.BaseOperation`2.OnCompleted()
   at IdeaBlade.EntityModel.BaseOperation`2.IdeaBlade.EntityModel.IHasAsyncEventArgs.OnCompleted()
   at IdeaBlade.EntityModel.AsyncProcessor`1.<>c__DisplayClass2.<.ctor>b__0(TArgs args)
   at IdeaBlade.EntityModel.AsyncProcessor`1.Signal()
   at IdeaBlade.EntityModel.AsyncProcessor`1.<Execute>b__5(Object x)
 
If that helps, then I have a workaround that works:
In the view model I create this property:

        private const string _p_loggerName = "p_loggerName";

        public string p_loggerName

        {

            get

            {

                if (p_currentItem == null)

                    return null;

                return p_entOpcGroup.p_loggerLink.p_logger.p_name;

            }

        }

And then I use my LazyLoad service to grab the EntityAspect.PendingEntityResolved first for p_loggerLink ('b') and if that returns me not NullEntity in the resolved-event handler then I grab EntityAspect.PendingEntityResolved for p_logger ('c') and calls RaisePropertyChanged("p_loggerName");

       

 
Then I do the XMAL binding such:

Text="{Binding p_vm.p_loggerName, Source={StaticResource ViewModelLocator}, Mode=OneWay}"

My LazyLoad service checks if the 'b' navigation property is an NullEntity or not before it decides to grab PendignEntityResolved for navigation property 'c' and raise property changed event for "p_loggerName".  I could belive you forgot the null entity check of 'b'....just a theory :-)
]]> Fri, 21 Jan 2011 09:35:57 -700 http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=9736#9736 Async Navigation in SL with PropertyChanged events : tj262, can you also include a... http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=9735#9735 Author: kimj
Subject: 2247
Posted: 21-Jan-2011 at 8:32am

tj262, can you also include a screen shot of the additional exception text?  It's cut off the stack trace where EnumerableFns.ForEach is called, and we'd like to see more of the stack trace to see what triggered the enumeration.

]]> Fri, 21 Jan 2011 08:32:40 -700 http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=9735#9735 Async Navigation in SL with PropertyChanged events : Oh dam it, I was using 6.0.6.... http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=9733#9733 Author: tj62
Subject: 2247
Posted: 21-Jan-2011 at 4:09am

Oh dam it, I was using 6.0.6. I upgraded and every thing works like a dream except on particular thing, that I think is a bug!
 
Let us call Navigation Property 'NP' in the description below.
If you have an entity 'a' that has a NP 'b' where 'b' has another NP 'c'. Then you want to bind to for example
a.b.c.name in XAML somthing like:
    Text="{Binding b.c.name, Mode=OneWay}"
where the the parent control has data context bound such:
    DataContext="{Binding a, Mode=TwoWay}"

This works fine as long as 'b' is not a NullEntity.  Unfortunately in my case b is nullable and therefore in that case the bound text box shold display empty. What happens however is that Visual Studio Just In Time Debugger pops up with this message:
An unhandled exception ('Unhandled Error in Silverlihgt Applicatoin Code: 4004
Categorey: ManagerdRuntimeError
Message: System.InvalidOperationException: Collection was modified;
enumeration operation may not execute.
Entering the debuger (if run without debugging) requests "eval code".
 
This is quite well known error indicating that a collection is modified in a foreach loop or similar.
 
I have uploaded screenshot from the debugger, as well as table structure I'm deailing with in the database when this happens if that helps:  uploads/508/NaviagationBug.zip
 
 
]]> Fri, 21 Jan 2011 04:09:08 -700 http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=9733#9733 Async Navigation in SL with PropertyChanged events : We actually did implement the... http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=9728#9728 Author: kimj
Subject: 2247
Posted: 20-Jan-2011 at 11:13am

We actually did implement the feature proposed by pompomjuice in the 6.0.7 release.  In addition to the PendingEntityResolved and PendingEntityListResolved events, the PropertyChanged event will fire for the navigation property.]]> Thu, 20 Jan 2011 11:13:59 -700 http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=9728#9728 Async Navigation in SL with PropertyChanged events : I hit the same wall I think. I... http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=9722#9722 Author: tj62
Subject: 2247
Posted: 20-Jan-2011 at 1:29am

I hit the same wall I think.  I have to hook everything up on the PendingEntityResolved event. To simplify that I created a "SericeLazyLoade.cs" class to avoid repeted code for this all over the place. And now I can do:

m_serviceLazyLoadDeviceItem = new ServiceLazyLoad(this, "p_currentItem", GetLazyEntity, true);

m_serviceLazyLoadDeviceItem.AddBoundProperty(typeof(EntDeviceItem), null, "p_deviceItemName");

m_serviceLazyLoadDeviceItem.AddBoundProperty(typeof(EntUom), null, "p_uomShortcut");

 
Wich will call OnPropertyChanged for the lazy loaded  "p_deviceItemName" and "p_uomShortcut" when loded.
But I sure agree with pompomJuce that having this out of the box would be very powerfull!!!
Is that planned?
]]> Thu, 20 Jan 2011 01:29:55 -700 http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=9722#9722 Async Navigation in SL with PropertyChanged events : That would be awesome. I am using... http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=8867#8867 Author: pompomJuice
Subject: 2247
Posted: 21-Oct-2010 at 12:56am

That would be awesome.

I am using a RadCombobox at the moment and its selected item is bound to Entity.NavitionalProperty. That binding would cause a async navigation on NavigationalProperty which would then not update the UI because there is no PropertyChanged event for the binding to feed on :(
Currently trying to compensate by extending entities to scan all their navigational properties for pending events and calling OnPropertyChanged within them. But its a schlep.... and its not working for some reason.


Edited by pompomJuice - 21-Oct-2010 at 1:15am]]> Thu, 21 Oct 2010 00:56:06 -700 http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=8867#8867 Async Navigation in SL with PropertyChanged events : That&#039;s a good question! We&#039;ve... http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=8858#8858 Author: kimj
Subject: 2247
Posted: 20-Oct-2010 at 3:01pm

That's a good question!  We've opened a feature request to look into it.]]> Wed, 20 Oct 2010 15:01:45 -700 http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=8858#8858 Async Navigation in SL with PropertyChanged events : I was wondering why you guys choseto... http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=8847#8847 Author: pompomJuice
Subject: 2247
Posted: 20-Oct-2010 at 2:27am

I was wondering why you guys chose to only use PendingEntityResolved events to enable us to hook into Async navigational upades. Surely using the conventional PropertyChanged event fireing mechanism would work perfectly with async navigation.
 
Now I have to hook up all these updates manually where it just could have worked out of the box?
]]> Wed, 20 Oct 2010 02:27:49 -700 http://www.ideablade.com/forum/forum_posts.asp?TID=2247&PID=8847#8847