How to configure Serilog's ContainsKey-Filter in a external JSON config file?

Question

How can I configure the filter lc.Filter.ByIncludingOnly(lc => lc.Properties.ContainsKey("log_gp") in a external applicationsettings.json file? I tried

  "Filter": [
    {
      "Name": "ByIncludingOnly",
      "Args": {
        "expression": "Contains(Properties, 'log_gp')"
      }
    }
  ]

but no success. Thanks

Answer 1

dotnet add package serilog.expressions

then:

  "Using": ["Serilog.Expressions"],
  "Filter": [
    {
      "Name": "ByIncludingOnly",
      "Args": {
        "expression": "IsDefined(log_gp)"
      }
    }
  ]