public static TMetadataView GetMetadataView <TMetadataView>(IDictionary <string, object?> metadata)
{
if (metadata == null)
{
throw new ArgumentNullException(nameof(metadata));
}
Type metadataViewType = typeof(TMetadataView);
// If the Metadata dictionary is cast compatible with the passed in type
if (metadataViewType.IsAssignableFrom(typeof(IDictionary <string, object?>)))
{
return((TMetadataView)metadata);
}
// otherwise is it a metadata view
else
{
Type?proxyType = null;
MetadataViewGenerator.MetadataViewFactory?metadataViewFactory = null;
if (metadataViewType.IsInterface)
{
if (!metadataViewType.IsAttributeDefined <MetadataViewImplementationAttribute>())
{
try
{
metadataViewFactory = MetadataViewGenerator.GetMetadataViewFactory(metadataViewType);
}
catch (TypeLoadException ex)
{
throw new NotSupportedException(SR.Format(SR.NotSupportedInterfaceMetadataView, metadataViewType.FullName), ex);
}
}
else
{
var implementationAttribute = metadataViewType.GetFirstAttribute <MetadataViewImplementationAttribute>();
Debug.Assert(implementationAttribute != null);
proxyType = implementationAttribute.ImplementationType;
if (proxyType == null)
{
throw new CompositionContractMismatchException(SR.Format(
SR.ContractMismatch_MetadataViewImplementationCanNotBeNull,
metadataViewType.FullName));
}
else
{
if (!metadataViewType.IsAssignableFrom(proxyType))
{
throw new CompositionContractMismatchException(SR.Format(
SR.ContractMismatch_MetadataViewImplementationDoesNotImplementViewInterface,
metadataViewType.FullName,
proxyType.FullName));
}
}
}
}
else
{
proxyType = metadataViewType;
}
// Now we have the type for the proxy create it
try
{
if (metadataViewFactory != null)
{
return(MetadataViewGenerator.CreateMetadataView <TMetadataView>(metadataViewFactory, metadata));
}
else
{
if (proxyType == null)
{
throw new Exception(SR.Diagnostic_InternalExceptionMessage);
}
return((TMetadataView)proxyType.SafeCreateInstance(metadata) !);
}
}
catch (MissingMethodException ex)
{
// Unable to create an Instance of the Metadata view '{0}' because a constructor could not be selected. Ensure that the type implements a constructor which takes an argument of type IDictionary<string, object>.
throw new CompositionContractMismatchException(SR.Format(
SR.CompositionException_MetadataViewInvalidConstructor,
proxyType !.AssemblyQualifiedName), ex);
}
catch (TargetInvocationException ex)
{
//Unwrap known failures that we want to present as CompositionContractMismatchException
if (metadataViewType.IsInterface)
{
if (ex.InnerException !.GetType() == typeof(InvalidCastException))
{
// Unable to create an Instance of the Metadata view {0} because the exporter exported the metadata for the item {1} with the value {2} as type {3} but the view imports it as type {4}.
throw new CompositionContractMismatchException(SR.Format(
SR.ContractMismatch_InvalidCastOnMetadataField,
ex.InnerException.Data[MetadataViewGenerator.MetadataViewType],
ex.InnerException.Data[MetadataViewGenerator.MetadataItemKey],
ex.InnerException.Data[MetadataViewGenerator.MetadataItemValue],
ex.InnerException.Data[MetadataViewGenerator.MetadataItemSourceType],
ex.InnerException.Data[MetadataViewGenerator.MetadataItemTargetType]), ex);
}
else if (ex.InnerException.GetType() == typeof(NullReferenceException))
{
// Unable to create an Instance of the Metadata view {0} because the exporter exported the metadata for the item {1} with a null value and null is not a valid value for type {2}.
throw new CompositionContractMismatchException(SR.Format(
SR.ContractMismatch_NullReferenceOnMetadataField,
ex.InnerException.Data[MetadataViewGenerator.MetadataViewType],
ex.InnerException.Data[MetadataViewGenerator.MetadataItemKey],
ex.InnerException.Data[MetadataViewGenerator.MetadataItemTargetType]), ex);
}
}
throw;
}
}