ASP.NET Core项目中使用NLog记录操作日志

  ASP.NET Core支持与多种第三方日志程序集成，具体清单见下面的截图。本文介绍ASP.NET Core项目中使用NLog程序记录程序。

  NLog是一个开源的、灵活的日志框架，它支持多个版本.net中集成调用，具体清单如下所示。

  NLog支持将日志记录到控制台、本地文件、数据库等位置，本文记录如何在ASP.NET Core项目中添加NLog，并将日志输出到控制台、本地文件。
  打开之前创建的电影数据维护程序，在VSCode终端中执行下列命令添加NLog相关引用。

	dotnet add package NLog
	dotnet add package NLog.Web.AspNetCore

  在program.cs文件的CreateHostBuilder中启用NLog

	...
	using NLog.Web;
	...

	namespace TestMVCMysqL
	{
	    public class Program
	    {
	        ...
	
	        public static IHostBuilder CreateHostBuilder(string[] args) =>
	            Host.CreateDefaultBuilder(args)
	                .ConfigureWebHostDefaults(webBuilder =>
	                {
	                    webBuilder.UseStartup<Startup>();
	                }).UseNLog();
	         
	        ...
	    }
	}

  在控制器类中增加日志属性，并通过构造函数传入日志实例，然后在增删改查函数中开头处加入日志记录代码。

	public class MovieController : Controller
    {
        private readonly RazorPagesMovieContext _context;
        private readonly ILogger<MovieController> _logger;

        public MovieController(RazorPagesMovieContext context,ILogger<MovieController> logger)
        {
            _context = context;
            _logger=logger;
        }
        ...
        ...
        [HttpPost, ActionName("Delete")]
        [ValidateAntiForgeryToken]
        public IActionResult DeleteConfirmed(int id)
        {            
            _logger.Log@R_242_4045@ion(string.Format("DeleteConfirmed movie(id={0})",id));
            var movie = _context.Movies.SingleOrDefault(m => m.Id == id);
            _context.Movies.Remove(movie);
            _context.SaveChanges();
            return RedirectToAction("Index");
        }
        ...
        ...
     }

  最后在项目根目录下新建nlog.config文件，然后复制参考文件5中的配置并进行调整（主要是修改参考文献5中的日志文件路径）。配置文件中，targets节用于定义写入位置（通过type属性设置)，本文中主要是命令行和本地文件，而rules节定义写入规则。

	<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      autoReload="true"
      internalLogLevel="Info"
      internalLogFile="nlog-AspNetCore.txt">

  <!-- enable asp.net core layout renderers -->
  <extensions>
    <add assembly="NLog.Web.AspNetCore"/>
  </extensions>

  <!-- the targets to write to -->
  <targets>
    <!-- File Target for all log messages with basic details -->
    <target xsi:type="File" name="allfile" fileName="nlog-AspNetCore-all-${shortdate}.log"
            layout="${longdate}|${event-properties:item=EventId_Id:whenEmpty=0}|${uppercase:${level}}|${logger}|${message} ${exception:format=tostring}" />

    <!-- File Target for own log messages with extra web details using some ASP.NET core renderers -->
    <target xsi:type="File" name="ownFile-web" fileName="nlog-AspNetCore-own-${shortdate}.log"
            layout="${longdate}|${event-properties:item=EventId_Id:whenEmpty=0}|${uppercase:${level}}|${logger}|${message} ${exception:format=tostring}|url: ${aspnet-request-url}|action: ${aspnet-mvc-action}|${callsite}| body: ${aspnet-request-posted-body}" />

    <!--Console Target for hosting lifetime messages to improve Docker / Visual Studio startup detection -->
    <target xsi:type="Console" name="lifetimeConsole" layout="${level:truncate=4:lowercase=true}: ${logger}[0]${newline}      ${message}${exception:format=tostring}" />
  </targets>

  <!-- rules to map from logger name to target -->
  <rules>
    <!--All logs, including from Microsoft-->
    <logger name="*" minlevel="Trace" writeto="allfile" />

    <!--Output hosting lifetime messages to console target for faster startup detection -->
    <logger name="Microsoft.Hosting.Lifetime" minlevel="Info" writeto="lifetimeConsole, ownFile-web" final="true" />

    <!--Skip non-critical Microsoft logs and so log only own logs (BlackHole) -->
    <logger name="Microsoft.*" maxlevel="Info" final="true" />
    <logger name="System.Net.Http.*" maxlevel="Info" final="true" />
    
    <logger name="*" minlevel="Trace" writeto="ownFile-web" />
  </rules>
</nlog>

  最后是运行效果，运行电影数据维护程序，点击删除、编辑、查看详细信息等链接后，控制台中的输出如下所示：

  本地文件中记录的日志内容如下：

  将日志记录到数据库中相对而言更复杂一些，需要在nlog.config中做更多的配置，后续还会继续学习记录。

参考文献：
[1]https://docs.microsoft.com/zh-cn/aspnet/core/mvc/models/validation?view=aspnetcore-5.0
[2]https://docs.microsoft.com/zh-cn/aspnet/core/fundamentals/logging/?view=aspnetcore-5.0#third-party-logging-providers
{3]https://blog.csdn.net/qin_yu_2010/article/details/81395098
[4]https://nlog-project.org/
[5]https://github.com/NLog/NLog/wiki/Getting-started-with-ASP.NET-Core-5
[6]https://zhaobingwang.blog.csdn.net/article/details/81568747?spm=1001.2101.3001.6650.6&utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7EOPENSEARCH%7Edefault-6.no_search_link&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7EOPENSEARCH%7Edefault-6.no_search_link
[7]https://github.com/NLog/NLog