如何让Serilog文件接收器输出键名带引号的合法JSON日志？

问题核心在于文件接收器的输出模板未指定结构化日志格式器：控制台接收器使用了{Message:lj}格式符（其中lj代表LiteralJson，会将结构化数据序列化为标准JSON），而文件接收器仅用{Message}，默认采用简洁的非JSON格式输出，导致键名不带引号。

只需修改appsettings.json中文件接收器的outputTemplate，将{Message}替换为{Message:lj}即可：

{
  "AllowedHosts": "*",
  "Serilog": {
    "MinimumLevel": {
      "Default": "Information",
      "Override": {
        "Microsoft.Hosting.Lifetime": "Information",
        "Microsoft": "Warning",
        "System": "Warning"
      }
    },
    "Enrich": [ "FromLogContext" ],
    "WriteTo": [
      {
        "Name": "Console",
        "Args": {
          "outputTemplate": "{Timestamp:HH:mm:ss.fff} {Level:u3} {SourceContext} {Message:lj}{NewLine:1}{Exception:1}"
        }
      },
      {
        "Name": "File",
        "Args": {
          "path": "logs/log.log",
          "rollingInterval": "Day",
          "outputTemplate": "{Timestamp:yyyy-MM-dd HH:mm:ss.fff}|{Level:u3}|{SourceContext}|{Message:lj}{NewLine:1}{Exception:1}"
        }
      }
    ]
  }
}

修改后，文件日志的结构化数据会和控制台输出一致，呈现合法JSON格式：

2023-01-27 08:09:38.880|INF|My.Test|HERE IT IS
2023-01-27 08:09:38.884|INF|My.Test|HERE IT IS {"Foo": "bar"}
2023-01-27 08:09:38.888|INF|My.Test|HERE IS ANOTHER ONE {"x": 1, "y": "2"}
2023-01-27 08:09:38.889|INF|My.Test|HERE IS DATA {"Name": "my data", "Value": 27.82859584, "IsValid": true, "$type": "Data"}

内容的提问来源于stack exchange，提问作者monty