.NET 6 NLog進階範例

目的

在寫nlog.config檔案時覺得怎麼有點複雜，我只是需要簡單的設定檔就好了，最後決定透過appsetting來做設定
將log文件採用非同步寫入，可大幅提升效能

建立新專案

選擇ASP.NET Core Web API專案範本，並執行下一步

設定新的專案

命名你的專案名稱，並選擇專案要存放的位置。

其他資訊

直接進行下一步

4.NuGet加入套件

NLog
NLog.Web.AspNetCore

編輯Program.cs檔

using NLog;
using NLog.Web;
//初始化NLog
var logger = LogManager.Setup()
  //載入Configuration並且讀取appsetting來使用
  .LoadConfigurationFromAppSettings()
  .GetCurrentClassLogger();
try {
  logger.Debug("init main");
  var builder = WebApplication.CreateBuilder(args);

  // Add services to the container.
  builder.Logging.ClearProviders();
  builder.Host.UseNLog();
  builder.Services.AddControllers();
  // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
  builder.Services.AddEndpointsApiExplorer();
  builder.Services.AddSwaggerGen();
  //以下省略

編輯appsetting.json

設定NLog，包含

throwConfigExceptions:設定檔錯誤時會跳exception
使用非同步方式寫入檔案
targets:設定輸出的格式，例如txt檔案或是Console顯示
rules:什麼情況要做什麼動作，例如log名稱為Microsoft.AspNetCore最小等級是warn時寫到Console

ILogger

NLog

Level 0

Trace

Level 1

Debug

Level 2

Information

Info

Level 3

Warning

Warn

Level 4

Error

Level 5

Critical

Fatal

Level 6

None

NLog沒有

{
  "NLog": {
    "throwConfigExceptions": true,
    "targets": {
      "async": true,
      "logfile": {
        "type": "File",
        "fileName": "c:/temp/nlog-${shortdate}.txt"
      },
      "logconsole": {
        "type": "Console"
      }
    },
    "rules": [
      {
        "logger": "Microsoft.AspNetCore",
        "minLevel": "Warn",
        "writeTo": "logconsole"
      },
      {
        "logger": "*",
        "minLevel": "Info",
        "writeTo": "logfile"
      }
    ]
  }
}

編輯WeatherForecastController.cs類別檔

    [HttpGet(Name = "GetWeatherForecast")]
    public IEnumerable<WeatherForecast> Get() {
      //新增一個類型
      var StudentObject = new Student() { Id = 4, Name = "Bill", Age = 20 };
      //新增一個匿名類型
      var position = new { Latitude = 25, Longitude = 134 };
      //寫log等級為error的log，當需要紀錄物件時需要透過{@該物件}來表示
      _logger.LogError("Error Value: {@StudentObject}", StudentObject);
      _logger.LogError("Error Value: {@position}", position);
      return Enumerable.Range(1, 5).Select(index => new WeatherForecast {
        Date = DateTime.Now.AddDays(index),
        TemperatureC = Random.Shared.Next(-20, 55),
        Summary = Summaries[Random.Shared.Next(Summaries.Length)]
      })
      .ToArray();
    }
    public class Student {
      public int Id { get; set; }
      public string Name { get; set; }
      public int Age { get; set; }
    }

執行結果

第一個紅框處顯示物件內容

結論

最後其實會發現Serilog相對來說比較容易使用，也建議使用serilog

參考

黑暗執行緒中文輸出為unicode問題 target參數中文解說非同步使用方式與縮寫

範例檔

GitHub

Previous.NET 6 NLog範例 Next.NET 6 Serilog範例

Last updated 1 year ago

using NLog; using NLog.Web; //初始化NLog var logger = LogManager.Setup() //載入Configuration並且讀取appsetting來使用 .LoadConfigurationFromAppSettings() .GetCurrentClassLogger(); try { logger.Debug("init main"); var builder = WebApplication.CreateBuilder(args); // Add services to the container. builder.Logging.ClearProviders(); builder.Host.UseNLog(); builder.Services.AddControllers(); // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle builder.Services.AddEndpointsApiExplorer(); builder.Services.AddSwaggerGen(); //以下省略

{ "NLog": { "throwConfigExceptions": true, "targets": { "async": true, "logfile": { "type": "File", "fileName": "c:/temp/nlog-${shortdate}.txt" }, "logconsole": { "type": "Console" } }, "rules": [ { "logger": "Microsoft.AspNetCore", "minLevel": "Warn", "writeTo": "logconsole" }, { "logger": "*", "minLevel": "Info", "writeTo": "logfile" } ] } }

[HttpGet(Name = "GetWeatherForecast")] public IEnumerable<WeatherForecast> Get() { //新增一個類型 var StudentObject = new Student() { Id = 4, Name = "Bill", Age = 20 }; //新增一個匿名類型 var position = new { Latitude = 25, Longitude = 134 }; //寫log等級為error的log，當需要紀錄物件時需要透過{@該物件}來表示 _logger.LogError("Error Value: {@StudentObject}", StudentObject); _logger.LogError("Error Value: {@position}", position); return Enumerable.Range(1, 5).Select(index => new WeatherForecast { Date = DateTime.Now.AddDays(index), TemperatureC = Random.Shared.Next(-20, 55), Summary = Summaries[Random.Shared.Next(Summaries.Length)] }) .ToArray(); } public class Student { public int Id { get; set; } public string Name { get; set; } public int Age { get; set; } }