Introduce ExposeKeyedServicesAttribute.

docs/en/Dependency-Injection.md

@@ -143,6 +143,36 @@ public class TaxCalculator : ITaxCalculator, ITransientDependency
 }
 ````
 
+### ExposeKeyedService Attribute 
+
+``ExposeKeyedServiceAttribute`` is used to control which keyed services are provided by the related class. Example:
+
+````C#
+[ExposeKeyedService<ITaxCalculator>("taxCalculator")]
+[ExposeKeyedService<ICalculator>("calculator")]
+public class TaxCalculator: ICalculator, ITaxCalculator, ICanCalculate, ITransientDependency
+{
+}
+````
+
+``TaxCalculator`` class exposes ``ITaxCalculator`` interface with the key ``tax`` and ``ICalculator`` interface with the key ``calculator``. That means you can get keyed services from the ``IServiceProvider`` as shown below:
+
+````C#
+var taxCalculator = ServiceProvider.GetRequiredKeyedService<ITaxCalculator>("taxCalculator");
+var calculator = ServiceProvider.GetRequiredKeyedService<ICalculator>("calculator");
+````
+
+> Notice that the ``ExposeKeyedServiceAttribute`` is only expose keyed services. So, you can not inject ``ITaxCalculator`` or ``ICalculator`` in your application. If you want to expose both keyed and non-keyed services, you can use ``ExposeServicesAttribute`` and ``ExposeKeyedServiceAttribute`` together as shown below:
+
+````C#
+[ExposeKeyedService<ITaxCalculator>("taxCalculator")]
+[ExposeKeyedService<ICalculator>("calculator")]
+[ExposeServices(typeof(ITaxCalculator), typeof(ICalculator))]
+public class TaxCalculator: ICalculator, ITaxCalculator, ICanCalculate, ITransientDependency
+{
+}
+````
+
 ### Manually Registering
 
 In some cases, you may need to register a service to the `IServiceCollection` manually, especially if you need to use custom factory methods or singleton instances. In that case, you can directly add services just as [Microsoft documentation](https://docs.microsoft.com/en-us/aspnet/core/fundamentals/dependency-injection) describes. Example:

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/ConventionalRegistrarBase.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
-using JetBrains.Annotations;
 using Microsoft.Extensions.DependencyInjection;
 using Volo.Abp.Reflection;
 
@@ -40,6 +39,11 @@ protected virtual bool IsConventionalRegistrationDisabled(Type type)
     }
 
     protected virtual void TriggerServiceExposing(IServiceCollection services, Type implementationType, List<Type> serviceTypes)
+    {
+        TriggerServiceExposing(services, implementationType, serviceTypes.ConvertAll(t => new ServiceIdentifier(t)));
+    }
+
+    protected virtual void TriggerServiceExposing(IServiceCollection services, Type implementationType, List<ServiceIdentifier> serviceTypes)
     {
         var exposeActions = services.GetExposingActionList();
         if (exposeActions.Any())
@@ -92,10 +96,16 @@ protected virtual List<Type> GetExposedServiceTypes(Type type)
         return ExposedServiceExplorer.GetExposedServices(type);
     }
 
+    protected virtual List<ServiceIdentifier> GetExposedKeyedServiceTypes(Type type)
+    {
+        return ExposedServiceExplorer.GetExposedKeyedServices(type);
+    }
+
     protected virtual ServiceDescriptor CreateServiceDescriptor(
         Type implementationType,
+        object? serviceKey,
         Type exposingServiceType,
-        List<Type> allExposingServiceTypes,
+        List<ServiceIdentifier> allExposingServiceTypes,
         ServiceLifetime lifeTime)
     {
         if (lifeTime.IsIn(ServiceLifetime.Singleton, ServiceLifetime.Scoped))
@@ -108,27 +118,41 @@ protected virtual ServiceDescriptor CreateServiceDescriptor(
 
             if (redirectedType != null)
             {
-                return ServiceDescriptor.Describe(
-                    exposingServiceType,
-                    provider => provider.GetService(redirectedType)!,
-                    lifeTime
-                );
+                return serviceKey == null
+                    ? ServiceDescriptor.Describe(
+                        exposingServiceType,
+                        provider => provider.GetService(redirectedType)!,
+                        lifeTime
+                    )
+                    : ServiceDescriptor.DescribeKeyed(
+                        exposingServiceType,
+                        serviceKey,
+                        (provider, key) => provider.GetKeyedService(redirectedType, key)!,
+                        lifeTime
+                    );
             }
         }
 
-        return ServiceDescriptor.Describe(
-            exposingServiceType,
-            implementationType,
-            lifeTime
-        );
+        return serviceKey == null
+            ? ServiceDescriptor.Describe(
+                exposingServiceType,
+                implementationType,
+                lifeTime
+            )
+            : ServiceDescriptor.DescribeKeyed(
+                exposingServiceType,
+                serviceKey,
+                implementationType,
+                lifeTime
+            );
     }
 
     protected virtual Type? GetRedirectedTypeOrNull(
         Type implementationType,
         Type exposingServiceType,
-        List<Type> allExposingServiceTypes)
+        List<ServiceIdentifier> allExposingKeyedServiceTypes)
     {
-        if (allExposingServiceTypes.Count < 2)
+        if (allExposingKeyedServiceTypes.Count < 2)
         {
             return null;
         }
@@ -138,14 +162,13 @@ protected virtual ServiceDescriptor CreateServiceDescriptor(
             return null;
         }
 
-        if (allExposingServiceTypes.Contains(implementationType))
+        if (allExposingKeyedServiceTypes.Any(t => t.ServiceType == implementationType))
         {
             return implementationType;
         }
 
-        return allExposingServiceTypes.FirstOrDefault(
-            t => t != exposingServiceType && exposingServiceType.IsAssignableFrom(t)
-        );
+        return allExposingKeyedServiceTypes.FirstOrDefault(
+            t => t.ServiceType != exposingServiceType && exposingServiceType.IsAssignableFrom(t.ServiceType)
+        ).ServiceType;
     }
-
 }

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/DefaultConventionalRegistrar.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Collections.Generic;
+using System.Linq;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 
@@ -22,16 +24,21 @@ public override void AddType(IServiceCollection services, Type type)
             return;
         }
 
-        var exposedServiceTypes = GetExposedServiceTypes(type);
+        var exposedServiceAndKeyedServiceTypes = GetExposedKeyedServiceTypes(type).Concat(GetExposedServiceTypes(type).Select(t => new ServiceIdentifier(t))).ToList();
 
-        TriggerServiceExposing(services, type, exposedServiceTypes);
+        TriggerServiceExposing(services, type, exposedServiceAndKeyedServiceTypes);
 
-        foreach (var exposedServiceType in exposedServiceTypes)
+        foreach (var exposedServiceType in exposedServiceAndKeyedServiceTypes)
         {
+            var allExposingServiceTypes = exposedServiceType.ServiceKey == null
+                ? exposedServiceAndKeyedServiceTypes.Where(x => x.ServiceKey == null).ToList()
+                : exposedServiceAndKeyedServiceTypes.Where(x => x.ServiceKey?.ToString() == exposedServiceType.ServiceKey?.ToString()).ToList();
+
             var serviceDescriptor = CreateServiceDescriptor(
                 type,
-                exposedServiceType,
-                exposedServiceTypes,
+                exposedServiceType.ServiceKey,
+                exposedServiceType.ServiceType,
+                allExposingServiceTypes,
                 lifeTime.Value
             );
 

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/ExposeKeyedServiceAttribute.cs

@@ -0,0 +1,25 @@
+using System;
+
+namespace Volo.Abp.DependencyInjection;
+
+[AttributeUsage(AttributeTargets.Class, AllowMultiple = true)]
+public class ExposeKeyedServiceAttribute<TServiceType> : Attribute, IExposedKeyedServiceTypesProvider
+    where TServiceType : class
+{
+    public ServiceIdentifier ServiceIdentifier { get; }
+
+    public ExposeKeyedServiceAttribute(object serviceKey)
+    {
+        if (serviceKey == null)
+        {
+            throw new AbpException($"{nameof(serviceKey)} can not be null! Use {nameof(ExposeServicesAttribute)} instead.");
+        }
+
+        ServiceIdentifier = new ServiceIdentifier(serviceKey, typeof(TServiceType));
+    }
+
+    public ServiceIdentifier[] GetExposedServiceTypes(Type targetType)
+    {
+        return new[] { ServiceIdentifier };
+    }
+}

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/ExposeServicesAttribute.cs

@@ -5,6 +5,7 @@
 
 namespace Volo.Abp.DependencyInjection;
 
+[AttributeUsage(AttributeTargets.Class, AllowMultiple = true)]
 public class ExposeServicesAttribute : Attribute, IExposedServiceTypesProvider
 {
     public Type[] ServiceTypes { get; }

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/ExposedServiceExplorer.cs

@@ -15,12 +15,31 @@ public static class ExposedServiceExplorer
 
     public static List<Type> GetExposedServices(Type type)
     {
-        return type
+        var exposedServiceTypesProviders = type
             .GetCustomAttributes(true)
             .OfType<IExposedServiceTypesProvider>()
+            .ToList();
+
+        if (exposedServiceTypesProviders.IsNullOrEmpty() && type.GetCustomAttributes(true).OfType<IExposedKeyedServiceTypesProvider>().Any())
+        {
+            // If there is any IExposedKeyedServiceTypesProvider but no IExposedServiceTypesProvider, we will not expose the default services.
+            return Array.Empty<Type>().ToList();
+        }
+
+        return exposedServiceTypesProviders
             .DefaultIfEmpty(DefaultExposeServicesAttribute)
             .SelectMany(p => p.GetExposedServiceTypes(type))
             .Distinct()
             .ToList();
     }
+
+    public static List<ServiceIdentifier> GetExposedKeyedServices(Type type)
+    {
+        return type
+            .GetCustomAttributes(true)
+            .OfType<IExposedKeyedServiceTypesProvider>()
+            .SelectMany(p => p.GetExposedServiceTypes(type))
+            .Distinct()
+            .ToList();
+    }
 }

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/IExposedKeyedServiceTypesProvider.cs

@@ -0,0 +1,8 @@
+using System;
+
+namespace Volo.Abp.DependencyInjection;
+
+public interface IExposedKeyedServiceTypesProvider
+{
+    ServiceIdentifier[] GetExposedServiceTypes(Type targetType);
+}

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/IOnServiceExposingContext.cs

@@ -7,5 +7,5 @@ public interface IOnServiceExposingContext
 {
     Type ImplementationType { get; }
 
-    List<Type> ExposedTypes { get; }
+    List<ServiceIdentifier> ExposedTypes { get; }
 }

framework/src/Volo.Abp.Core/Volo/Abp/DependencyInjection/OnServiceExposingContext.cs

@@ -8,9 +8,15 @@ public class OnServiceExposingContext : IOnServiceExposingContext
 {
     public Type ImplementationType { get; }
 
-    public List<Type> ExposedTypes { get; }
+    public List<ServiceIdentifier> ExposedTypes { get; }
 
     public OnServiceExposingContext([NotNull] Type implementationType, List<Type> exposedTypes)
+    {
+        ImplementationType = Check.NotNull(implementationType, nameof(implementationType));
+        ExposedTypes = Check.NotNull(exposedTypes, nameof(exposedTypes)).ConvertAll(t => new ServiceIdentifier(t));
+    }
+
+    public OnServiceExposingContext([NotNull] Type implementationType, List<ServiceIdentifier> exposedTypes)
     {
         ImplementationType = Check.NotNull(implementationType, nameof(implementationType));
         ExposedTypes = Check.NotNull(exposedTypes, nameof(exposedTypes));

framework/src/Volo.Abp.ObjectMapping/Volo/Abp/ObjectMapping/AbpObjectMappingModule.cs

@@ -1,4 +1,5 @@
 using Microsoft.Extensions.DependencyInjection;
+using Volo.Abp.DependencyInjection;
 using Volo.Abp.Modularity;
 using Volo.Abp.Reflection;
 
@@ -10,12 +11,12 @@ public override void PreConfigureServices(ServiceConfigurationContext context)
     {
         context.Services.OnExposing(onServiceExposingContext =>
         {
-                //Register types for IObjectMapper<TSource, TDestination> if implements
-                onServiceExposingContext.ExposedTypes.AddRange(
+            //Register types for IObjectMapper<TSource, TDestination> if implements
+            onServiceExposingContext.ExposedTypes.AddRange(
                 ReflectionHelper.GetImplementedGenericTypes(
                     onServiceExposingContext.ImplementationType,
                     typeof(IObjectMapper<,>)
-                )
+                ).ConvertAll(t => new ServiceIdentifier(t))
             );
         });
     }

framework/src/Volo.Abp.Serialization/Volo/Abp/Serialization/AbpSerializationModule.cs

@@ -1,4 +1,5 @@
 using Microsoft.Extensions.DependencyInjection;
+using Volo.Abp.DependencyInjection;
 using Volo.Abp.Modularity;
 using Volo.Abp.Reflection;
 
@@ -10,12 +11,12 @@ public override void PreConfigureServices(ServiceConfigurationContext context)
     {
         context.Services.OnExposing(onServiceExposingContext =>
         {
-                //Register types for IObjectSerializer<T> if implements
-                onServiceExposingContext.ExposedTypes.AddRange(
+            //Register types for IObjectSerializer<T> if implements
+            onServiceExposingContext.ExposedTypes.AddRange(
                 ReflectionHelper.GetImplementedGenericTypes(
                     onServiceExposingContext.ImplementationType,
                     typeof(IObjectSerializer<>)
-                )
+                ).ConvertAll(t => new ServiceIdentifier(t))
             );
         });
     }