为什么 DictionaryValue 在 ASP.NET Core 中的 Serilog 中转换为 ScalarValue

Question

My Serilog configuration is the following:

    LevelSwitch.MinimumLevel = LogEventLevel.Verbose;

    var loggerConfiguration =
        new LoggerConfiguration()
            .MinimumLevel.ControlledBy(LevelSwitch)
            .Enrich.FromLogContext()
            .WriteTo.Conditional(
                IsDictionaryValue,
                cfg => cfg.Console());

    services.AddLogging(configure => configure.AddSerilog());

where the IsDictionaryValue is defined as:

    static bool IsDictionaryValue(LogEvent logEvent)
    {
        if (logEvent.Properties.TryGetValue("LOG_TEST", out LogEventPropertyValue value))
        {
            return value is DictionaryValue;
        }

        return false;
    }

trying to log trace and information message:

    var logger = loggerFactory.CreateLogger<Program>();

    var dict = new Dictionary<string, object>
    {
        { "val1", 1 },
        { "val2", 2 },
        { "val3", "_3" },
    };

    logger.LogTrace("{@LOG_TEST}", dict);

    logger.LogInformation("{@LOG_TEST}", dict);

The question is:
Why in ASP.NET Core web app the log trace message correctly creates DictionaryValue and the result of IsDictionaryValue is true , but when I log information message, the LogEventPropertyValue value is ScalarValue .

BUT
This "bug" is only in ASP.NET Core web app. When I use the same Serilog configuration in Console app, both LogTrace and LogInformation, correctly represents the dict dictionary as DictionaryValue .

Update:
type of LogEventPropertyValue in DictionaryValue

Log method	Console App	Web app
LogTrace	DictionaryValue	DictionaryValue
LogDebug	DictionaryValue	DictionaryValue
LogInformation	DictionaryValue	ScalarValue
LogWarning	DictionaryValue	ScalarValue
LogError	DictionaryValue	ScalarValue
LogCritical	DictionaryValue	ScalarValue

Answer 1

The problem:
In ASP.NET Core are registered some default LoggerProviders like:

1. Microsoft.Extensions.Logging.Console.ConsoleLogger
2. Microsoft.Extensions.Logging.Debug.DebugLogger
3. Microsoft.Extensions.Logging.EventSource.EventSourceLogger
4. Microsoft.Extensions.Logging.EventLog.EventLogLogger

and when you configure serilog

services.AddLogging(configure => configure.AddSerilog());

the fifth LoggerProvider was added:

5. Serilog.Extensions.Logging.SerilogLogger

The default configuration for other providers is LogLevel:Information . This is the reason why LogTrace and LogDebug works in Web app. So if you call LogInformation the first four logger providers hits the TState in

namespace Microsoft.Extensions.Logging
{
    internal class Logger : ILogger
    {
        public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
    }
}

and it converts the original dictionary to string . And when the fifth logger provider (out SerilogLogger ) comes to play, it cannot resolve DictionaryValue because the TState is string

The solution:
Set the SerilogLogger as the first LoggerProvider :

    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                })
            .ConfigureLogging(cfg => cfg
                .ClearProviders()
                .AddSerilog()
                .AddConsole()
                .AddDebug()
                .AddEventSourceLogger()
                .AddEventLog());
    }

and because the SerilogLoggerProvider is registered in Program.cs within IHostBuilder , the AddSerilog() in services.AddLogging(configure => configure.AddSerilog()); is not necessary.

services.AddLogging();