Prism IRegionManager updateregion is throwing IndexOutOfRangeEception.

Question

Prism IRegionManager updateregion is throwing IndexOutOfRangeEception.

K C, Soniya 21

Below exception is seen from framework side sporadically when we tried accessing RegionManager.Regions["FullScreen"].

In general if the region is not created/deactivated/removed either nullException or KeyNotFound exception should be thrown.

Here is the code : (crashed at if check)
if (this.myRegionManager.Regions["FullScreen"] == null)
{
//Log error to a file
}

Exception details:

      - Unhandled exception:

Sender: Name: MyProject.exe
There are no context policies.
Runtime Terminating: True
App.FailOnThreadException: True
System.IndexOutOfRangeException: Index was outside the bounds of the array.
at System.Array.Clear(Array array, Int32 index, Int32 length)
at System.Collections.Generic.List1.RemoveAll(Predicate1 match)
at Prism.Events.WeakDelegatesManager.Raise(Object[] args)
at Prism.Regions.RegionManager.UpdateRegions()
at Prism.Regions.RegionManager.RegionCollection.get_Item(String regionName)
at MyProject.Tool.<ViewData>d__22.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
at System.Threading.ThreadPoolWorkQueue.Dispatch()

Please let us why there is exception and how to avoid it.

DaisyTian-1203 11,646 Reputation points

2021-06-11T02:21:51.77+00:00

@K C, Soniya
The IndexOutOfRangeEception that is thrown when an attempt is made to access an element of an array or collection with an index that is outside its bounds. But I can't analyze the reason for the error based on the code you provided. Did you add the region named FullScreen to myRegionManager? Please provide me enough code to make a sample to reproduce your error.
K C, Soniya 21 Reputation points

2021-06-11T05:44:35.91+00:00

Regions variable cannot be set by any client application its internal to PRISM not sure why IndexofRange is thrown.
If Regions is empty by any chance as per documentation(I have tested) KeyNotFound exception would be thrown.

Here is the code snippet :

void ViewData()
{
if (this.mRegionManager.Regions[mRegions.FullScreen] == null)
{
Trace.Error(myTraceDomain, string.Format(CultureInfo.InvariantCulture, "Region name {0} does not exist", mRegions.FullScreen));
return;
}

if (this.mView == null)
{
this.mView = new OverviewView(new OverviewViewModel(this.mModel));
this.mRegionManager.AddToRegion(mRegions.FullScreen, this.mView);
this.mView.Focusable = true;
}
}

Your answer

DaisyTian-1203 11,646 Reputation points

2021-06-11T02:21:51.77+00:00

@K C, Soniya
The IndexOutOfRangeEception that is thrown when an attempt is made to access an element of an array or collection with an index that is outside its bounds. But I can't analyze the reason for the error based on the code you provided. Did you add the region named FullScreen to myRegionManager? Please provide me enough code to make a sample to reproduce your error.
K C, Soniya 21 Reputation points

2021-06-11T05:44:35.91+00:00

Regions variable cannot be set by any client application its internal to PRISM not sure why IndexofRange is thrown.
If Regions is empty by any chance as per documentation(I have tested) KeyNotFound exception would be thrown.

Here is the code snippet :

void ViewData()
{
if (this.mRegionManager.Regions[mRegions.FullScreen] == null)
{
Trace.Error(myTraceDomain, string.Format(CultureInfo.InvariantCulture, "Region name {0} does not exist", mRegions.FullScreen));
return;
}

if (this.mView == null)
{
this.mView = new OverviewView(new OverviewViewModel(this.mModel));
this.mRegionManager.AddToRegion(mRegions.FullScreen, this.mView);
this.mView.Focusable = true;
}
}

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Prism IRegionManager updateregion is throwing IndexOutOfRangeEception.

Your answer