.net core使用NLog记录

 首先使用nugut安装nlog, nlog.extensions.logging,using nlog.web，并且加上配置文件 ”nlog.config“,配置文件内容网上都可以百度的到。这是我自己的：

创建表：

create table `sys_log` (
`id` int(11) not null auto_increment,
`account` varchar(20) character set utf8 collate utf8_general_ci null default null,
`actiontype` varchar(10) character set utf8 collate utf8_general_ci null default null,
`level` varchar(5) character set utf8 collate utf8_general_ci null default null,
`message` longtext character set utf8 collate utf8_general_ci null,
`date` datetime(0) null default null,
primary key (`id`) using btree,
unique index `id_unique`(`id`) using btree
) engine = innodb auto_increment = 11 character set = utf8 collate = utf8_general_ci row_format = compact;

  配置config文件

<?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"
xsi:schemalocation="http://www.nlog-project.org/schemas/nlog.xsd nlog.xsd"
autoreload="true"
throwexceptions="true"
internalloglevel="off" internallogfile="c:\temp\nlog-internal.log">

<!-- optional, add some variables
https://github.com/nlog/nlog/wiki/configuration-file#variables
-->
<variable name="myvar" value="myvalue"/>

<!--
-->
<targets>
<target name="console" xsi:type ="console" />
<target name="debugger" xsi:type="debugger" layout="${date:format=hh\:mm\:ss.fff}: ${message}" />
<target name="error_file" xsi:type="file"
filename="${basedir}/logs/error/${shortdate}/error.txt" maxarchivefiles="30"
layout="${longdate} | ${level:uppercase=false} | ${message} ${onexception:${exception:format=tostring} ${newline} ${stacktrace} ${newline}" />
<target name="info" xsi:type="file"
filename="${basedir}/logs/info/${shortdate}/info.txt" maxarchivefiles="30"
layout="${longdate} | ${level:uppercase=false} | ${message} ${onexception:${exception:format=tostring} ${newline} ${stacktrace} ${newline}" />
<target name="database" xsi:type="database">
<connectionstring>${var:connectionstrings}</connectionstring>
<commandtext>
insert into lifehome.sys_log (account,actiontype,level,message,date) values(@account,@actiontype,@level,@message,@date)
</commandtext>
<parameter name = "@account" layout = "${event-context:item=account}"/>
<parameter name = "@actiontype" layout = "${event-context:item=actiontype}"/>
<parameter name = "@level" layout = "${event-context:item=level}" />
<parameter name = "@message" layout = "${event-context:item=message}" />
<parameter name = "@date" layout = "${event-context:item=date}" />
<dbprovider>mysql.data.mysqlclient.mysqlconnection,mysql.data</dbprovider>
</target>
</targets>
<rules>
<logger name="*" writeto="console" />
<logger name="*" minlevel="debug" writeto="debugger" />
<logger name="*" minlevel="error" writeto="error_file" />
<logger name="*" level="info" writeto="info" />
<logger name="*" writeto="database" />
</rules>
</nlog>

 因为之前一直无法将日志写入数据库，于是百度了好久，将”throwexceptions“设置为true，部署在生产环境建议改为false，这样就可以调试看到错误了，我的原因是sql错误。

  <connectionstring>此处是为了灵活配置sql连接。

 之后在startup.cs里面加上如下代码：

public void configure(iapplicationbuilder app, ihostingenvironment env,iloggerfactory loggerfactory)
{

         //加载nlog
         loggerfactory.addnlog();

         //加载配置文件
         env.configurenlog("nlog.config");

         //读取数据库连接
         nlog.logmanager.configuration.variables["connectionstrings"]=_configuration.getconnectionstring("connection");

      );
   });
}

然后在program.cs里面写上

public static iwebhost buildwebhost(string[] args) =>
   webhost.createdefaultbuilder(args)
    .usestartup<startup>().usenlog()
.       build();

然后使用过滤器

  

/// <summary>
/// 全局异常过滤
/// </summary>
public class exceptionfilter : attribute,iexceptionfilter
{
     private readonly ilogger logger;
     public exceptionfilter()
     {
          logger = logmanager.getcurrentclasslogger();
      }
      public void onexception(exceptioncontext context)
      {

       //如果异常未处理
     if(context.exceptionhandled==false)
       {
          logeventinfo lei = new logeventinfo();
          lei.level = loglevel.error;
          lei.properties["account"] = "1";
          lei.properties["date"] =datetime.now;
          lei.properties["actiontype"] = "1";
          lei.properties["level"] = "1";
          lei.properties["message"] = "1";
          logger.log(lei);
          //异常已处理
         context.exceptionhandled = true;
    }
   }
}

 数据可以记录到数据库，但是使用简单写法如： logger.error("12344")还未成功