无法在 NLog 中设置我的连接字符串

Question

NLog.config 文件没有设置连接字符串。

<?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="Warn"
      internalLogFile="c:\temp\internal-nlog.txt">

  <!-- Load the ASP.NET Core plugin -->
  <extensions>
    <add assembly="NLog.Web.AspNetCore" />
  </extensions>
  <variable name="SirNLogDb" value="data source=SQL_MULALLEY;initial catalog=LogFiles;User ID=xxx;Password=yyy;">
  </variable>
  <!--  providerName="System.Data.SqlClient"-->

  <!-- the targets to write to -->
  <targets>
    <target name="db"
            xsi:type="Database"
            dbProvider="System.Data.SqlClient"
            connectionString="${var:SirNLogDb}"
            commandType="StoredProcedure"
            commandText="[dbo].[NLog_AddEntry_p]">
      <parameter name="@machineName"    layout="${machinename}" />
      <parameter name="@siteName"       layout="${iis-site-name}" />
      <parameter name="@logged"         layout="${date}" />
      <parameter name="@level"          layout="${level}" />
      <parameter name="@username"       layout="${aspnet-user-identity}" />
      <parameter name="@message"        layout="${message}" />
      <parameter name="@logger"         layout="${logger}" />
      <parameter name="@properties"     layout="${all-event-properties:separator=|}" />
      <parameter name="@serverName"     layout="${aspnet-request:serverVariable=SERVER_NAME}" />
      <parameter name="@port"           layout="${aspnet-request:serverVariable=SERVER_PORT}" />
      <parameter name="@url"            layout="${aspnet-request:serverVariable=HTTP_URL}" />
      <parameter name="@https"          layout="${when:inner=1:when='${aspnet-request:serverVariable=HTTPS}' == 'on'}${when:inner=0:when='${aspnet-request:serverVariable=HTTPS}' != 'on'}" />
      <parameter name="@serverAddress"  layout="${aspnet-request:serverVariable=LOCAL_ADDR}" />
      <parameter name="@remoteAddress"  layout="${aspnet-request:serverVariable=REMOTE_ADDR}:${aspnet-request:serverVariable=REMOTE_PORT}" />
      <parameter name="@callSite"       layout="${callsite}" />
      <parameter name="@exception"      layout="${exception:tostring}" />
    </target>
  </targets>

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

我下了断点，连接字符串为空；

我的启动方法如下；

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvcCore()
            .AddMvcOptions(o => o.OutputFormatters.Add(
                new JsonOutputFormatter(new JsonSerializerSettings(), ArrayPool<char>.Shared)));
        var connectionStringMSurveyV2 = Configuration.GetConnectionString("MSurveyV2Db");
        services.AddScoped<MSurveyV2Db>(_ => new MSurveyV2Db(connectionStringMSurveyV2));
        var connectionStringSir = Configuration.GetConnectionString("SirDb");
        services.AddScoped<SirDb>(_ => new SirDb(connectionStringSir));
        services.AddScoped<IPropertiesRepo, PropertiesRepo>();
        services.AddScoped<ISirUoW, SirUoW>();
        services.AddScoped<Services.IMailService, Services.MailService>();
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        loggerFactory.AddConsole();
        loggerFactory.AddDebug();
        loggerFactory.AddNLog();
        //add NLog.Web
        app.AddNLogWeb();

        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseExceptionHandler();
        }

        app.UseMvc();
        AutoMapper.Mapper.Initialize(cfg =>
        {
            cfg.CreateMap<Exception, OperationStatus>();
            cfg.CreateMap<ViewSelectedContracts, ContractDto>();
        });
        var logger = LogManager.GetCurrentClassLogger();
        logger.Info("Logged in");
    }
}

编辑 - 我将记录器规则更改为 <logger name="*" minlevel="Trace" writeTo="db" /> 但它仍然没有输出任何内容。但是我查找了 c:\temp\internal-nlog.txt 并且它还没有被创建。所以 nlog.config 文件似乎被忽略了。但它在我的项目中 Startup.cs 文件旁边。

EDIT2：- 可以通过将 "Copy to output directory" 设置为 "copy always" 来解决空配置。从下面的评论中，我现在已经开始工作了。

Answer 1

更新答案

自 NLog.Web.AspNetCore 4.8（NLog.Extensions.Logging 1.4 用于 .NET Core 控制台程序）您可以直接从 appSettings.json

中读取

${configsetting:name=MyConnectionString}

见docs

原回答

不幸的是，NLog for .NET core 尚不支持从 appSettings.json/app.config 读取 connectionstrings/settings。

两个选项：

使用变量以编程方式设置连接字符串。在你的 nlog.config 中：

<target ... connectionString="${var:myConnectionstring}"  ... />

并在代码中：（例如在 Configure 中）

LogManager.Configuration.Variables["myConnectionstring"] = "...."; //read config here

或者，在nlog.config中设置连接字符串。

在你的 nlog.config:

<variable name="myConnectionstring" value="...." />

并在 nlog.config 的目标中使用：

<target ... connectionString="${var:myConnectionstring}" ... />

Answer 2

另一种选择是创建并注册自定义 NLog 布局渲染器 (startup.cs):

https://github.com/NLog/NLog/wiki/How-to-write-a-custom-layout-renderer

从您最喜欢的配置位置读取 ConnectionString 后输出它。那么你的 nlog.config 中没有连接字符串，而只是参考你的自定义布局渲染器。

也许为这个悬而未决的问题欢呼：

https://github.com/NLog/NLog.Web/issues/107

无法在 NLog 中设置我的连接字符串

Unable to set my connectionstring in NLog

c#

nlog

appsettings

asp.net-core

更新答案

原回答