Introduced AddNLog for IServiceCollection

src/NLog.Extensions.Logging/Config/NLogLoggingConfiguration.cs

@@ -303,7 +303,7 @@ private IEnumerable<ILoggingConfigurationElement> GetChildren(IEnumerable<IConfi
                 }
             }
 
-            private IEnumerable<IConfigurationSection> GetVariablesChildren(IConfigurationSection variables)
+            private static IEnumerable<IConfigurationSection> GetVariablesChildren(IConfigurationSection variables)
             {
                 List<KeyValuePair<string, IConfigurationSection>> sortVariables = null;
                 foreach (var variable in variables.GetChildren())

src/NLog.Extensions.Logging/Extensions/ConfigureExtensions.cs

@@ -4,7 +4,6 @@
 using Microsoft.Extensions.Configuration;
 #if !NETCORE1_0
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.DependencyInjection.Extensions;
 #endif
 using Microsoft.Extensions.Logging;
 using NLog.Common;
@@ -197,6 +196,52 @@ public static ILoggingBuilder AddNLog(this ILoggingBuilder builder, NLogProvider
             return builder;
         }
 
+        /// <summary>
+        /// Enable NLog as logging provider for Microsoft Extension Logging
+        /// </summary>
+        /// <param name="collection"></param>
+        /// <returns>IServiceCollection for chaining</returns>
+        public static IServiceCollection AddNLog(this IServiceCollection collection)
+        {
+            return AddNLog(collection, NLogProviderOptions.Default);
+        }
+
+        /// <summary>
+        /// Enable NLog as logging provider for Microsoft Extension Logging
+        /// </summary>
+        /// <param name="collection"></param>
+        /// <param name="options">NLog Logging Provider options</param>
+        /// <returns>IServiceCollection for chaining</returns>
+        public static IServiceCollection AddNLog(this IServiceCollection collection, NLogProviderOptions options)
+        {
+            Guard.ThrowIfNull(collection);
+            collection.TryAddNLogLoggingProvider((svc, addlogging) => svc.AddLogging(addlogging), null, options, CreateNLogLoggerProvider);
+            return collection;
+        }
+
+        /// <summary>
+        /// Enable NLog as logging provider for Microsoft Extension Logging
+        /// </summary>
+        /// <param name="collection"></param>
+        /// <param name="options">NLog Logging Provider options</param>
+        /// <param name="factoryBuilder">Initialize NLog LogFactory with NLog LoggingConfiguration.</param>
+        /// <returns>IServiceCollection for chaining</returns>
+        public static IServiceCollection AddNLog(this IServiceCollection collection, NLogProviderOptions options, Func<IServiceProvider, LogFactory> factoryBuilder)
+        {
+            Guard.ThrowIfNull(collection);
+            Guard.ThrowIfNull(factoryBuilder);
+            collection.TryAddNLogLoggingProvider((svc, addlogging) => svc.AddLogging(addlogging), null, options, (serviceProvider, config, opt) =>
+            {
+                config = serviceProvider.SetupNLogConfigSettings(config, LogManager.LogFactory);
+
+                // Delay initialization of targets until we have loaded config-settings
+                var logFactory = factoryBuilder(serviceProvider);
+                var provider = CreateNLogLoggerProvider(serviceProvider, config, opt, logFactory);
+                return provider;
+            });
+            return collection;
+        }
+
         private static void AddNLogLoggerProvider(ILoggingBuilder builder, IConfiguration hostConfiguration, NLogProviderOptions options, Func<IServiceProvider, IConfiguration, NLogProviderOptions, NLogLoggerProvider> factory)
         {
             builder.Services.TryAddNLogLoggingProvider((svc, addlogging) => addlogging(builder), hostConfiguration, options, factory);

src/NLog.Extensions.Logging/Internal/RegisterNLogLoggingProvider.cs

@@ -2,7 +2,6 @@
 {
     using System;
     using System.Linq;
-    using System.Reflection;
     using Microsoft.Extensions.Configuration;
 #if !NETCORE1_0
     using Microsoft.Extensions.DependencyInjection;

test/NLog.Extensions.Logging.Tests/Extensions/ConfigureExtensionsTests.cs

@@ -158,6 +158,46 @@ public void AddNLog_ReplaceLoggerFactory()
             Assert.Equal(typeof(NLogLoggerProvider), loggerProvider.GetType());
         }
 
+        [Fact]
+        public void AddNLog_ServiceCollection_ReplaceLoggerFactory()
+        {
+            // Arrange
+            var collection = new ServiceCollection();
+
+            // Act
+            collection.AddNLog(new NLogProviderOptions() { ReplaceLoggerFactory = true });
+
+            // Assert
+            using var provider = collection.BuildServiceProvider();
+            var loggerFactory = provider.GetService<ILoggerFactory>();
+            Assert.NotNull(loggerFactory);
+            Assert.Equal(typeof(NLogLoggerFactory), loggerFactory.GetType());
+        }
+
+        [Fact]
+        public void AddNLog_ServiceCollection_ShouldLog()
+        {
+            // Arrange
+            var collection = new ServiceCollection();
+
+            // Act
+            var nlogTarget = new Targets.MemoryTarget() { Name = "Output" };
+            collection.AddNLog(new NLogProviderOptions(), (ServiceProvider) =>
+            {
+                var nLogFactory = new LogFactory().Setup().LoadConfiguration(c => c.ForLogger().WriteTo(nlogTarget)).LogFactory;
+                return nLogFactory;
+            });
+
+            // Assert
+            using var provider = collection.BuildServiceProvider();
+            var loggerFactory = provider.GetService<ILoggerFactory>();
+            Assert.NotNull(loggerFactory);
+
+            var logger = loggerFactory.CreateLogger("Hello");
+            logger.LogCritical("World");
+            Assert.Single(nlogTarget.Logs);
+        }
+
         [Fact]
         public void AddNLog_ArgumentNullException()
         {