Read connectionstrings from appsettings.json to nlog.config

-Read connectionstrings from appsettings.json to nlog.config

Read connectionstrings from appsettings.json to nlog.config

nlog.config

<?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="false"
     internalLogLevel="Off" internalLogFile="c:\temp\nlog-internal.log">

  <!-- optional, add some variables
 https://github.com/nlog/NLog/wiki/Configuration-file#variables
 -->
  <variable name="app-name" value="xxx Common Project"/>

  <extensions>
    <add assembly="NLog.Appsettings.Standard" />
    <!-- write your dll file name that includes custom layout renderer -->
    <add assembly="YourDLLFileName" />
  </extensions>

  <targets>



    <target xsi:type="FallbackGroup" name="EMailOrFileOrDb" returnToFirstOnSuccess="true">
      <!--Write events and send mail-->


      <target name="database" xsi:type="Database" connectionString="${connectionstrings:name=DatabaseContext}" >
        <commandText>
          insert into dbo.Logs (
          AppName, LogDate, Username,Type,Process,Entity,Description,UserId
          ) values (
          @AppName, @LogDate, @Username,@Type,@Process,@Entity,@Description,0
          );
        </commandText>

        <parameter name="@AppName" layout="${app-name}" />
        <parameter name="@LogDate" layout="${date}" />
        <parameter name="@Username" layout="${username}" />
        <parameter name="@Type" layout="Exception Logs" />
        <parameter name="@Process" layout="Exception Logs" />
        <parameter name="@Entity" layout="${message}" />
        <parameter name="@Description" layout="Exception Logs" />
      </target>

      <target xsi:type="Mail" name="m"
            smtpServer="smtp.xxx.com" smtpPort="587"
            smtpUserName="noreply@xxx.xom" smtpPassword="xxx"
            smtpAuthentication="Basic"

              subject="${app-name} ${level} "
              layout="${date} ${uppercase:${level}} ${message}${newline}${newline}"
              body="
               &lt;b&gt;Datetime : &lt;/b&gt;${date}${newline}
               &lt;b&gt;Version : &lt;/b&gt;${assembly-version}${newline}
               &lt;b&gt;Username : &lt;/b&gt;${username}${newline}${newline}

               &lt;b&gt;Controller : &lt;/b&gt;${aspnet-mvc-controller}${newline}
               &lt;b&gt;Action : &lt;/b&gt;${aspnet-mvc-action}${newline}
               &lt;b&gt;Req. Url : &lt;/b&gt;${aspnet-request-url}${newline}
               &lt;b&gt;Req. Querystring : &lt;/b&gt;${aspnet-request-querystring}${newline}${newline}

               ${message}${newline}${newline}"
              header="&lt;b&gt;Logger : &lt;/b&gt;${logger}${newline} &lt;b&gt;Level : &lt;/b&gt;${level}${newline}${newline}"
              footer="&lt;b&gt;&lt;small&gt;Bu e-posta xxx tarafından bilgilendirme amacıyla gönderilmiştir.&lt;/small&gt;&lt;/b&gt;"

              useSystemNetMailSettings="false"
              replaceNewlineWithBrTagInHtml="true"
              enableSsl="true" addNewLines="true" html="true"

              from="noreply@xxx.com" to="devops@xxx.com" cc="" bcc=""  />


      <!--Write events to a file with the date in the filename.-->
      <target xsi:type="File" name="f"
              fileName="${basedir}/logs/${shortdate}.log"
              layout="${longdate} ${uppercase:${level}} ${message}"
              encoding="utf-8" />






    </target>

  </targets>

  <rules>

    <logger name="*" minlevel="Debug" writeTo="EMailOrFileOrDb" />
  </rules>

</nlog>

NLog_ConnectionStringsLayoutRenderer.cs

[LayoutRenderer("connectionstrings")]
    public class ConnectionStringsLayoutRenderer : LayoutRenderer
    {
        private static IConfigurationRoot _configurationRoot;

        internal IConfigurationRoot DefaultAppSettings
        {
            get => _configurationRoot;
            set => _configurationRoot = value;
        }

        /// <summary>
        /// Global configuration. Used if it has set
        /// </summary>
        public static IConfiguration AppSettings { private get; set; }

        ///<summary>
		/// The AppSetting name.
		///</summary>
		[RequiredParameter]
        [DefaultParameter]
        public string Name { get; set; }

        ///<summary>
        /// The default value to render if the AppSetting value is null.
        ///</summary>
        public string Default { get; set; }

        public ConnectionStringsLayoutRenderer()
        {

            if (AppSettings == null && DefaultAppSettings == null)
            {
                DefaultAppSettings = new ConfigurationBuilder().SetBasePath(Directory.GetCurrentDirectory())
                    .AddJsonFile("appsettings.json")
                    .AddJsonFile($"appsettings.{Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT")}.json", optional: true).Build();
            }
        }

        /// <summary>
        /// Renders the specified application setting or default value and appends it to the specified <see cref="StringBuilder" />.
        /// </summary>
        /// <param name="builder">The <see cref="StringBuilder"/> to append the rendered data to.</param>
        /// <param name="logEvent">Logging event.</param>
        protected override void Append(StringBuilder builder, LogEventInfo logEvent)
        {
            if (Name == null) return;

            string value = AppSettingValue;
            if (value == null && Default != null)
                value = Default;

            if (string.IsNullOrEmpty(value) == false)
                builder.Append(value);
        }

        private bool _cachedAppSettingValue = false;
        private string _appSettingValue = null;
        private string AppSettingValue
        {
            get
            {
                Name = Name.Replace('.', ':');
                if (_cachedAppSettingValue == false)
                {
                    _appSettingValue = AppSettings == null ? DefaultAppSettings.GetConnectionString(Name) : AppSettings[Name];
                    _cachedAppSettingValue = true;
                }
                return _appSettingValue;
            }
        }
    }