private static IEnumerable <IViewModel> GetPossiblyStaleItems(
ValidationResult collectionResult,
ICollectionValidationTarget target
)
{
// This method is performance critical! It is not a good idea to loop
// through all items and call 'IsValid'. Remember that is method is called
// for each item of every collection (because the framework tries to
// perform a collection validation for every item).
var allDescendantsErrors = target
.Collection
.OwnerVM
.Kernel
.GetValidationResult(ValidationResultScope.Descendants)
.Errors;
var previouslyInvalidItems = allDescendantsErrors
.Where(e => e.OriginatedFrom(target))
.Select(e => e.Target.VM);
var failedItems = collectionResult
.Errors
.Select(x => x.Target.VM);
return(previouslyInvalidItems.Union(failedItems));
}
internal bool OriginatedFrom(ICollectionValidationTarget target)
{
Check.NotNull(target, nameof(target));
return
(Target.Step == target.Step &&
Target.Collection == target.Collection &&
Target.Property == target.Property);
}
public CollectionResult(
ICollectionValidationTarget target,
ValidationResult result,
IEnumerable <IViewModel> possiblyStaleItems
)
{
Target = target;
_result = result;
PossiblyStaleItems = possiblyStaleItems;
}
public static CollectionResult Validate(ICollectionValidationTarget target)
{
ValidationResult collectionResult = target
.Collection
.OwnerVM
.ExecuteValidationRequest(target.CreateValidationRequest());
var possiblyStaleItems = GetPossiblyStaleItems(collectionResult, target);
return(new CollectionResult(target, collectionResult, possiblyStaleItems));
}
private CollectionResult ValidateCollectionIfNotInCache(ICollectionValidationTarget target)
{
CollectionResult cachedResult = _cachedCollectionResults
.FirstOrDefault(cached => target.Equals(cached.Target));
if (cachedResult == null)
{
cachedResult = CollectionValidationController.Validate(target);
_cachedCollectionResults.Add(cachedResult);
foreach (IViewModel item in cachedResult.PossiblyStaleItems)
{
var r = new RevalidationRequest(item, target.Property);
EnqueueRevalidation(r);
}
}
return(cachedResult);
}
