Output with parameters in Serilog does no work

Question

In a .Net Core Webapi project I am using Serilog to log. But when I use _logger.LogInformation("Token for user {UserName} created",data.username); and check the log file, the output is "Token for user {Username} created". The {Username} is not replaced with the real value. I am sure that the value is not null.

I use this in a LoginService and the Serilog setting in the appsetting.json is

"Serilog": {
  "Using": [ "Serilog.Sinks.Console", "Serilog.Sinks.File" ],
  "MinimumLevel": {
    "Default": "Debug",
    "Override": {
      "Microsoft": "Information",
      "System": "Information"
    }
  },
  "WriteTo": [
    { "Name": "Console" },
    {
      "Name": "File",
      "Args": {
        "path": "C:\\Users\\ab\\Projects\\IQC\\IQC_Log.txt",
        "rollingInterval": "Day",
        "rollOnFileSizeLimit": true,
        "formatter": "Serilog.Formatting.Compact.CompactJsonFormatter"
      }
    }
  ]
}

Could someone help to point out where I did wrong?

Answer 1

Assuming you're getting JSON in that file as expected, the problem will be that you're using CompactJsonFormatter, which does not render message templates.

Instead, you need to pass Serilog.Formatting.Compact.RenderedCompactJsonFormatter for the formatter arg.