internal static IEnumerable <FilterAttribute> RemoveOverriddenFilters(IEnumerable <FilterAttribute> filters)
{
// If an attribute is declared on both the controller and on an action method and that attribute's
// type has AllowMultiple = false (which is the default for attributes), we should ignore the attributes
// declared on the controller. The CLR's reflection implementation follows a similar algorithm when it
// encounters an overridden virtual method where both the base and the override contain some
// AllowMultiple = false attribute.
// Key = attribute type
// Value = -1 if AllowMultiple true, last index of this attribute type if AllowMultiple false
Dictionary <Type, int> attrsIndexes = new Dictionary <Type, int>();
FilterAttribute[] filtersList = filters.ToArray();
for (int i = 0; i < filtersList.Length; i++)
{
FilterAttribute filter = filtersList[i];
Type filterType = filter.GetType();
int lastIndex;
if (attrsIndexes.TryGetValue(filterType, out lastIndex))
{
if (lastIndex >= 0)
{
// this filter already exists and AllowMultiple = false, so clear last entry
filtersList[lastIndex] = null;
attrsIndexes[filterType] = i;
}
}
else
{
// not found - add to dictionary
// exactly one AttributeUsageAttribute will always be present
bool allowMultiple = _allowMultiplAttributesCache.IsMultiUseAttribute(filterType);
attrsIndexes[filterType] = (allowMultiple) ? -1 : i;
}
}
// any duplicated attributes have now been nulled out, so just return remaining attributes
return(filtersList.Where(attr => attr != null));
}
/// <summary>
/// Composes the attributes.
/// </summary>
/// <param name="attributes">The attributes.</param>
void ComposeAttributes(FilterAttribute[] attributes)
{
CompositionProvider.Current.ComposeParts(attributes);
}
void ComposeAttributes(FilterAttribute[] attributes)
{
foreach (var attribute in attributes)
CompositionProvider.Current.SatisfyImports(attribute);
}
