private ICollection <TNav> GetNavCollection()
{
TParent parentItem;
IEnumerable <TNav> navEnumerable;
try
{
parentItem = _parentItem.LoadedItem;
navEnumerable = _navExpression.Compile().Invoke(parentItem);
}
catch (Exception ex)
{
throw new NotSupportedException("Error getting navigation collection from parent item.", ex);
}
if (navEnumerable == null)
{
var newList = new List <TNav>();
var castedList = newList as TCollection;
Debug.Assert(castedList != null, "This should always cast. Is it not covariant?");
_setter.SetNavItem(parentItem, castedList);
return(newList);
}
var navCollection = navEnumerable as ICollection <TNav>;
if (navCollection == null)
{
throw new NotSupportedException("Cannot add items to this navigation property because it does not implement ICollection.");
}
return(navCollection);
}
public async Task SetValueAsync(IDeferredItem <TItem> item, object deserializedValue, IDataTransaction dataTransaction)
{
TNav navValue = ConversionUtility.ConvertValue <TNav>(deserializedValue);
await item.LoadAsync();
_setter.SetNavItem(item.LoadedItem, navValue);
}
private void SetParentNavItem(TNav item)
{
var parent = _parentItem.Query.First();
_setter.SetNavItem(parent, item);
}