How do I get all types that implementing a specific open generic type?
For instance:
public interface IUserRepository : IRepository<User> Find all types that implement IRepository<>.
public static IEnumerable<Type> GetAllTypesImplementingOpenGenericType(Type openGenericType, Assembly assembly) { ... } This will return all types that inherit a generic base class. Not all types that inherit a generic interface.
var AllTypesOfIRepository = from x in Assembly.GetAssembly(typeof(AnyTypeInTargetAssembly)).GetTypes() let y = x.BaseType where !x.IsAbstract && !x.IsInterface && y != null && y.IsGenericType && y.GetGenericTypeDefinition() == typeof(IRepository<>) select x; This will return all types, including interfaces, abstracts, and concrete types that have the open generic type in its inheritance chain.
public static IEnumerable<Type> GetAllTypesImplementingOpenGenericType(Type openGenericType, Assembly assembly) { return from x in assembly.GetTypes() from z in x.GetInterfaces() let y = x.BaseType where (y != null && y.IsGenericType && openGenericType.IsAssignableFrom(y.GetGenericTypeDefinition())) || (z.IsGenericType && openGenericType.IsAssignableFrom(z.GetGenericTypeDefinition())) select x; } This second method will find ConcreteUserRepo and IUserRepository in this example:
public class ConcreteUserRepo : IUserRepository {} public interface IUserRepository : IRepository<User> {} public interface IRepository<User> {} public class User {} 
Solution implemented without LINQ, searching both generic and non generic interfaces, filtering the return type to classes.
public static class SampleCode { public static void Main() { IList<Type> loadableTypes; // instance the dummy class used to find the current assembly DummyClass dc = new DummyClass(); loadableTypes = GetClassesImplementingAnInterface(dc.GetType().Assembly, typeof(IMsgXX)).Item2; foreach (var item in loadableTypes) {Console.WriteLine("1: " + item);} // print // 1: Start2.MessageHandlerXY loadableTypes = GetClassesImplementingAnInterface(dc.GetType().Assembly, typeof(IHandleMessageG<>)).Item2; foreach (var item in loadableTypes) { Console.WriteLine("2: " + item); } // print // 2: Start2.MessageHandlerXY // 2: Start2.MessageHandlerZZ } ///<summary>Read all classes in an assembly that implement an interface (generic, or not generic)</summary> // // some references // return all types implementing an interface // http://stackoverflow.com/questions/26733/getting-all-types-that-implement-an-interface/12602220#12602220 // http://haacked.com/archive/2012/07/23/get-all-types-in-an-assembly.aspx/ // http://stackoverflow.com/questions/7889228/how-to-prevent-reflectiontypeloadexception-when-calling-assembly-gettypes // return all types implementing a generic interface // http://stackoverflow.com/questions/33694960/find-all-types-implementing-a-certain-generic-interface-with-specific-t-type // http://stackoverflow.com/questions/8645430/get-all-types-implementing-specific-open-generic-type // http://stackoverflow.com/questions/1121834/finding-out-if-a-type-implements-a-generic-interface // http://stackoverflow.com/questions/5849210/net-getting-all-implementations-of-a-generic-interface public static Tuple<bool, IList<Type>> GetClassesImplementingAnInterface(Assembly assemblyToScan, Type implementedInterface) { if (assemblyToScan == null) return Tuple.Create(false, (IList<Type>)null); if (implementedInterface == null || !implementedInterface.IsInterface) return Tuple.Create(false, (IList<Type>)null); IEnumerable<Type> typesInTheAssembly; try { typesInTheAssembly = assemblyToScan.GetTypes(); } catch (ReflectionTypeLoadException e) { typesInTheAssembly = e.Types.Where(t => t != null); } IList<Type> classesImplementingInterface = new List<Type>(); // if the interface is a generic interface if (implementedInterface.IsGenericType) { foreach (var typeInTheAssembly in typesInTheAssembly) { if (typeInTheAssembly.IsClass) { var typeInterfaces = typeInTheAssembly.GetInterfaces(); foreach (var typeInterface in typeInterfaces) { if (typeInterface.IsGenericType) { var typeGenericInterface = typeInterface.GetGenericTypeDefinition(); var implementedGenericInterface = implementedInterface.GetGenericTypeDefinition(); if (typeGenericInterface == implementedGenericInterface) { classesImplementingInterface.Add(typeInTheAssembly); } } } } } } else { foreach (var typeInTheAssembly in typesInTheAssembly) { if (typeInTheAssembly.IsClass) { // if the interface is a non-generic interface if (implementedInterface.IsAssignableFrom(typeInTheAssembly)) { classesImplementingInterface.Add(typeInTheAssembly); } } } } return Tuple.Create(true, classesImplementingInterface); } } public class DummyClass { } public interface IHandleMessageG<T> { } public interface IHandleMessage { } public interface IMsgXX { } public interface IMsgXY { } public interface IMsgZZ { } public class MessageHandlerXY : IHandleMessageG<IMsgXY>, IHandleMessage, IMsgXX { public string Handle(string a) { return "aaa"; } } public class MessageHandlerZZ : IHandleMessageG<IMsgZZ>, IHandleMessage { public string Handle(string a) { return "bbb"; } } 
assemblyToScan from single to an array of params params Assembly[] assembliesYou could try
openGenericType.IsAssignableFrom(myType.GetGenericTypeDefinition()) or
myType.GetInterfaces().Any(i => i.GetGenericTypeDefinition() = openGenericType) You can use the following code to get all types that implement IRepository<> interface:
List<Type> typesImplementingIRepository = new List<Type>(); IEnumerable<Type> allTypesInThisAssembly = Assembly.GetExecutingAssembly().GetTypes(); foreach (Type type in allTypesInThisAssembly) { if (type.GetInterface(typeof(IRepository<>).Name.ToString()) != null) { typesImplementingIRepository.Add(type); } } 