private static ServiceDescriptor GetMetadataServiceDescriptor <T>(Type ImplementationType)
{
return(ServiceDescriptor.Transient(typeof(Lazy <T, ServiceTypeMetadata>),
provider =>
new Lazy <T, ServiceTypeMetadata>(
() =>
(T)provider.GetRequiredService(ImplementationType),
ServiceTypeMetadataExtensions.GetServiceTypeMetadata(ImplementationType)
)));
}
public static IServiceCollection AddMetadataDependency(this IServiceCollection services, Func <AssemblyName, bool> predicate = null)
{
var assemblies = GetAssemblies(predicate);
var types = assemblies.SelectMany(i => i.GetExportedTypes())
.Where(t => t.GetTypeInfo()
.IsDefined(typeof(ServiceDescriptorAttribute), inherit: true)
);
foreach (var type in types)
{
var typeInfo = type.GetTypeInfo();
var attributes = typeInfo.GetCustomAttributes <ServiceDescriptorAttribute>().ToArray();
// Check if the type has multiple attributes with same ServiceType.
var duplicates = attributes
.GroupBy(s => s.ServiceType)
.SelectMany(grp => grp.Skip(1));
if (duplicates.Any())
{
throw new InvalidOperationException($@"Type ""{type.FullName}"" has multiple ServiceDescriptor attributes with the same service type.");
}
foreach (var attribute in attributes)
{
var serviceTypes = getRequireMetadataServiceTypes(type, attribute);
foreach (var serviceType in serviceTypes)
{
//
var descriptor = new ServiceDescriptor(serviceType, type, attribute.Lifetime);
services.Add(descriptor);
if (serviceType.IsInterface)
{
var extensionDescriptor = (ServiceDescriptor)getMetadataServiceDescriptorMethodInfo
.MakeGenericMethod(descriptor.ServiceType)
.Invoke(null, new object[] { descriptor.ImplementationType });
services.Add(extensionDescriptor);
ServiceTypeMetadataExtensions.AddMetadata(descriptor.ImplementationType, attribute.Name);
}
}
}
}
return(services);
}
