public TValue GetValue(IBehaviorContext context)
{
RequireInitialized();
if (!_cache.HasValue(context))
{
if (_isProviding.GetWithDefault(context, false))
{
// This check is important to avoid the following endless recursion:
// 1. GetValue calls ProvideValue
// 2. ProvideValue directly or indirectly calls GetValue
// 3. GetValue calls Provide value because the cache is not set yet.
// 4. ProvideValue calls GetValue again
//
// The alternative would be to return default(TValue) but it is better
// to avoid this situation altogehter.
throw new InvalidOperationException(EViewModels.ValueAccessedWithinProvideValue);
}
_isProviding.Set(context, true);
TValue value = ProvideValue(context);
_cache.Set(context, value);
_isProviding.Clear(context);
OnInitialize(context);
}
return(_cache.Get(context));
}
public void Refresh(IBehaviorContext context, RefreshOptions options)
{
// Call next behavior first, because a source accessor behavior may handle
// it.
this.RefreshNext(context, options);
_collectionSourceCache.Clear(context);
// ToArray so that (1) source is only enumerated once and (2) acess by index
// (required by the equality check) is guaranteed to be fast.
TItemSource[] newSourceItems = GetSourceItems(context).ToArray();
IVMCollection <TItemVM> vmCollection = GetValue(context);
IEnumerable <TItemVM> itemsToRefresh = Enumerable.Empty <TItemVM>();
if (AreCollectionContentsEqual(vmCollection, newSourceItems))
{
itemsToRefresh = vmCollection;
}
else
{
Dictionary <TItemSource, TItemVM> previousItemsBySource = vmCollection.ToDictionary(
x => x.Source,
_reusabilitySourceComparer
);
List <TItemVM> newItems = new List <TItemVM>();
List <TItemVM> reusedItems = new List <TItemVM>();
foreach (TItemSource s in newSourceItems)
{
TItemVM item;
bool isReusedItem = previousItemsBySource.TryGetValue(s, out item);
if (isReusedItem)
{
reusedItems.Add(item);
}
else
{
item = CreateAndInitializeItem(context, s);
}
newItems.Add(item);
}
vmCollection.ReplaceItems(newItems, RefreshReason.Create(options.ExecuteRefreshDependencies));
itemsToRefresh = reusedItems;
}
if (options.Scope.HasFlag(RefreshScope.Content))
{
itemsToRefresh
.ForEach(x => x.Kernel.RefreshWithoutValidation(options.ExecuteRefreshDependencies));
}
}
public void Revalidate(IBehaviorContext context)
{
ValidationController controller = _validationController.Get(context);
var validationResult = controller.GetResult(_step, context.VM, _property);
bool valueWasInvalid = _invalidValueCache.HasValue(context);
bool valueIsNotInvalidAnymore = validationResult.IsValid;
if (valueWasInvalid && valueIsNotInvalidAnymore)
{
TValue previouslyInvalidValue = _invalidValueCache.Get(context);
_invalidValueCache.Clear(context);
SetValueNext(context, previouslyInvalidValue);
}
else
{
this.PropertyRevalidateNext(context);
}
_resultManager.UpdateValidationResult(context, validationResult);
}
protected void RefreshCache(IBehaviorContext context)
{
_cache.Clear(context);
GetValue(context);
}
public void EndValidation(IBehaviorContext context)
{
_validationController.Clear(context);
this.EndValidationNext(context);
}
