ASP.NET Core 3.1系列（32）——NLog日志写入SQL Server数据库

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1、前言

前面介绍了NLog将日志写入文本文件的方法下面就来介绍一下如何将日志写入SQL Server数据库。

2、创建数据表

在SQL Server中新建一个数据库Dao然后创建日志表Log代码如下

USE [Dao]
GO

/****** Object:  Table [dbo].[Log]    Script Date: 2023/2/7 14:39:28 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[Log](
	[Id] [int] IDENTITY(1,1) NOT NULL,
	[MachineName] [nvarchar](50) NOT NULL,
	[Logged] [datetime] NOT NULL,
	[Level] [nvarchar](50) NOT NULL,
	[Message] [nvarchar](max) NOT NULL,
	[Logger] [nvarchar](250) NULL,
	[Callsite] [nvarchar](max) NULL,
	[Exception] [nvarchar](max) NULL,
 CONSTRAINT [PK_dbo.Log] PRIMARY KEY CLUSTERED 
(
	[Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
GO

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3、引入NLog

新建一个Web API工程使用NuGet引入如下组件

NLog
NLog.Database
NLog.Web.AspNetCore
Microsoft.Data.SqlClient

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4、配置文件nlog.config

新建一个XML文件文件名为nlog.config如下图所示

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将nlog.config文件改为始终复制如下图所示

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在nlog.config文件中添加如下代码

<?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="c:\temp\internal-nlog-AspNetCore.txt">
	<extensions>
		<add assembly="NLog.Web.AspNetCore"/>
	</extensions>
	<targets>
		<target name="db" xsi:type="Database">
			<!-- 连接字符串 -->
			<connectionString>Data Source=rt-dongshenfeng;Initial Catalog=Dao;User ID=sa;Password=123456</connectionString>
			<!-- Insert语句 -->
			<commandText>
				insert into dbo.Log (MachineName,Logged,Level,Message,Logger,Callsite,Exception) values (@MachineName,@Logged,@Level,@Message,@Logger,@Callsite,@Exception);
			</commandText>
			<!-- 格式化参数 -->
			<parameter name="@MachineName" layout="${machinename}" />
			<parameter name="@Logged" layout="${date}" />
			<parameter name="@Level" layout="${level}" />
			<parameter name="@Message" layout="${message}" />
			<parameter name="@Logger" layout="${logger}" />
			<parameter name="@Callsite" layout="${callsite}" />
			<parameter name="@Exception" layout="${exception:tostring}" />
		</target>
	</targets>
	<rules>
		<logger name="Microsoft.*" minlevel="Trace" final="true" />
		<logger name="*" minlevel="Info" writeTo="db" />
	</rules>
</nlog>

如果要将日志写入数据库则xsi:type的值为DatabaseconnectionString节点存放数据库连接字符串commandText节点存放插入数据的SQLparameter节点定义格式化参数名称和对应的值。

5、设置NLog为日志管理器

修改Program.cs文件代码如下

using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using NLog.Web;

namespace App
{
    public class Program
    {
        public static void Main(string[] args)
        {
            NLogBuilder.ConfigureNLog("nlog.config");
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                })
                .ConfigureLogging(logging=>
                {
                    logging.ClearProviders();
                })
                .UseNLog();
    }
}

6、生成日志

添加一个控制器HomeController在其构造函数中注入ILogger接口代码如下

using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;

namespace App.Controllers
{
    [Route("api/[controller]/[action]")]
    [ApiController]
    public class HomeController : ControllerBase
    {
        protected readonly ILogger<HomeController> _logger;

        public HomeController(ILogger<HomeController> logger)
        {
            _logger = logger;
        }

        [HttpGet]
        public ActionResult<string> Get()
        {
            _logger.LogTrace("This is track info");
            _logger.LogDebug("This is debug info");
            _logger.LogInformation("This is info");
            _logger.LogWarning("This is warn info");
            _logger.LogError("This is error info");
            _logger.LogCritical("This is fatal info");
            return "Hello World";
        }
    }
}