I have a .NET Core WEB API project and I would like to be a container for multiples "projects" as .NET CORE Class Library.
What I have is:
Solution "Orbit" with a .NET Core Web API project on it.
Solution "SpaceRadar" with a .NET Core Class Library.
First, inside my "Orbit" project, the Startup class, what I have made so far:
public void ConfigureServices(IServiceCollection services)
{
this.ConfigureMVC(services);
this.ConfigureIOC(services);
}
private void ConfigureMVC(IServiceCollection services)
{
IMvcBuilder mvcBuilder = services.AddMvc(option => { option.EnableEndpointRouting = false; });
// for each assembly inside modules directory, add the controllers
foreach (string assemblyPath in Directory.GetFiles($"{System.AppDomain.CurrentDomain.BaseDirectory}/Modules", "*.dll", SearchOption.AllDirectories))
{
var assembly = Assembly.LoadFile(assemblyPath);
mvcBuilder.AddApplicationPart(assembly);
}
}
This part works well, since we can trigger the Controller that is defined inside my SpaceRadar project. However I wanted to use dependency injection in my class library project, if possible by scanning the dll to get all the types that extends IScopedServices / ISingletonServices / ITransientServices.
But honestly, I have no idea where to register my interface and their respective implementation. I tried this solution:
private void ConfigureIOC(IServiceCollection services)
{
// Store all the type that need to be injected in the IOC system
List<Type> implementationTypes = new List<Type>();
List<Type> singletons = new List<Type>();
List<Type> scopeds = new List<Type>();
List<Type> transients = new List<Type>();
// for each assembly, load it, populate the type list of things to be injected
foreach (string assemblyPath in Directory.GetFiles(System.AppDomain.CurrentDomain.BaseDirectory, "*.dll", SearchOption.AllDirectories))
{
var assembly = System.Runtime.Loader.AssemblyLoadContext.Default.LoadFromAssemblyPath(assemblyPath);
implementationTypes.AddRange(assembly.GetExportedTypes().Where(type => type.IsClass && (type.GetInterface("ISingletonServices") != null || type.GetInterface("IScopedServices") != null || type.GetInterface("ITransientServices") != null)));
singletons.AddRange(assembly.GetExportedTypes().Where(type => type.IsInterface && type.GetInterface("ISingletonServices") != null));
scopeds.AddRange(assembly.GetExportedTypes().Where(type => type.IsInterface && type.GetInterface("IScopedServices") != null));
transients.AddRange(assembly.GetExportedTypes().Where(type => type.IsInterface && type.GetInterface("ITransientServices") != null));
}
// Register into the service collection
foreach (Type type in singletons)
{
services.AddSingleton(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
}
foreach (Type type in scopeds)
{
services.AddScoped(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
}
foreach (Type type in transients)
{
services.AddTransient(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
}
}
But it seems that there is a problem of context of the assembly. I tried also the Assembly.LoadFrom() but isn't working, the ReaderLoadContext solution found on a blog
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Runtime.Loader;
using System.Threading.Tasks;
namespace Orbit
{
public class ReaderLoadContext : AssemblyLoadContext
{
private AssemblyDependencyResolver _resolver;
public ReaderLoadContext(string readerLocation)
{
_resolver = new AssemblyDependencyResolver(readerLocation);
}
protected override Assembly Load(AssemblyName assemblyName)
{
string assemblyPath = _resolver.ResolveAssemblyToPath(assemblyName);
if (assemblyPath != null)
{
return LoadFromAssemblyPath(assemblyPath);
}
return null;
}
protected override IntPtr LoadUnmanagedDll(string unmanagedDllName)
{
string libraryPath = _resolver.ResolveUnmanagedDllToPath(unmanagedDllName);
if (libraryPath != null)
{
return LoadUnmanagedDllFromPath(libraryPath);
}
return IntPtr.Zero;
}
}
}
And even to call a "setup" method inside the assembly
private void ConfigureIOC(IServiceCollection services)
{
// for each assembly, load it, add the controller into the mvcBuilder and populate the type list of things to be injected
foreach (string assemblyPath in Directory.GetFiles($"{System.AppDomain.CurrentDomain.BaseDirectory}/Modules", "*.dll", SearchOption.AllDirectories))
{
Assembly assembly = Assembly.LoadFrom(assemblyPath);
Type startup = assembly.GetTypes().SingleOrDefault(t => t.Name == "Startup");
if (startup != null)
{
var setupMethod = startup.GetMethod("Setup");
setupMethod.Invoke(setupMethod, new Object[] { services });
}
}
}
and inside my class library
public static void Setup(IServiceCollection services)
{
List<Type> implementationTypes = new List<Type>();
List<Type> singletons = new List<Type>();
List<Type> scopeds = new List<Type>();
List<Type> transients = new List<Type>();
foreach (string assemblyPath in Directory.GetFiles(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location), "*.dll", SearchOption.AllDirectories))
{
var assembly = Assembly.Load(assemblyPath);
// get all Singleton, Scoped and Transient interfaces
implementationTypes.AddRange(assembly.GetTypes().Where(type => type.IsClass && (type.GetInterface("ISingletonServices") != null || type.GetInterface("IScopedServices") != null || type.GetInterface("ITransientServices") != null)));
singletons.AddRange(assembly.GetTypes().Where(type => type.IsInterface && type.GetInterface("ISingletonServices") != null));
scopeds.AddRange(assembly.GetTypes().Where(type => type.IsInterface && type.GetInterface("IScopedServices") != null));
transients.AddRange(assembly.GetTypes().Where(type => type.IsInterface && type.GetInterface("ITransientServices") != null));
}
// Register into the service collection
foreach (Type type in singletons)
{
services.AddSingleton(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
}
foreach (Type type in scopeds)
{
services.AddScoped(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
}
foreach (Type type in transients)
{
services.AddTransient(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
}
}
I also tried the HostingStartup attribute
[assembly: HostingStartup(typeof(SpaceRadar.ServiceKeyInjection))]
namespace SpaceRadar
{
public class ServiceKeyInjection : IHostingStartup
{
public void Configure(IWebHostBuilder builder)
{
builder.ConfigureServices((context, services) => {
List<Type> implementationTypes = new List<Type>();
List<Type> singletons = new List<Type>();
List<Type> scopeds = new List<Type>();
List<Type> transients = new List<Type>();
foreach (string assemblyPath in Directory.GetFiles(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location), "*.dll", SearchOption.AllDirectories))
{
var assembly = Assembly.Load(assemblyPath);
// get all Singleton, Scoped and Transient interfaces
implementationTypes.AddRange(assembly.GetTypes().Where(type => type.IsClass && (type.GetInterface("ISingletonServices") != null || type.GetInterface("IScopedServices") != null || type.GetInterface("ITransientServices") != null)));
singletons.AddRange(assembly.GetTypes().Where(type => type.IsInterface && type.GetInterface("ISingletonServices") != null));
scopeds.AddRange(assembly.GetTypes().Where(type => type.IsInterface && type.GetInterface("IScopedServices") != null));
transients.AddRange(assembly.GetTypes().Where(type => type.IsInterface && type.GetInterface("ITransientServices") != null));
}
// Register into the service collection
foreach (Type type in singletons)
{
services.AddSingleton(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
}
foreach (Type type in scopeds)
{
services.AddScoped(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
}
foreach (Type type in transients)
{
services.AddTransient(type, implementationTypes.Single(t => t.GetInterface(type.FullName) != null));
}
});
}
}
}
All this solutions doesn't allow me inside my class library to have this kind of controller:
public class RadarControllers : BaseControllers
{
private readonly IRadarServices _radarServices;
public RadarControllers(IRadarServices radarServices)
{
_radarServices = radarServices;
}
[HttpGet("radars")]
public async Task<IActionResult> GetRadars(CancellationToken cancellationToken)
{
IList<string> data = await _radarServices.GetRadars(cancellationToken);
return Ok(data);
}
}
How to proceed for this dependency injection ? Thanks.
I finally found a way to deals with that. The issue is that on each projet, the assembly name is the same (for instance : "Services"). .Net core does not like this and it seems that if I try to load through AssemblyLoadContext.Default.LoadFromAssemblyPath, it keep loading the same assembly no matter the path to indicate.
On the projet, I just right click > Properties and change the assembly name to an another. Thanks to that, AssemblyLoadContext.Default.LoadFromAssemblyPath(assemblyPath) works.
For instance, if I have project A and B, I rename the assembly names services with A.Services and B.Services
so The dll is now A.Services.dll instead of Services.dll