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conditional-statementsserilog

Multiple conditional branches in Serilog expression

We've started using Serilog to generate structure logs for our application. Using Serilog Expressions we've been able to generate the following JSON, which is fairly cool as far as logging goes.

{
    "@t": "2022-02-11T15:57:57.6087361+01:00",
    "@m": "GET Request received on API endpoint /foo",
    "@l": "Info",
    "SourceContext": "Company.API.FooController",
    "ActionId": "bd248542-138b-4053-9d50-b9e62e0ab1fd",
    "ActionName": "Company.API.FooController.GetFoo (Company.API)",
    "RequestId": "0HMFDDRDSMUUI:00000001",
    "RequestPath": "/foo",
    "SpanId": "|85c9c2db-489a260ce2c6915e.",
    "TraceId": "85c9c2db-489a260ce2c6915e",
    "ParentId": "",
    "ConnectionId": "0HMFDDRDSMUUI",
    "ThreadId": 7,
    "ContextFieldA": "ValueA",
    "ContextFieldB": "ValueA"
}

These log events are generated using the following expression, which is read from the environment variables:

"{ {@t, @m, @r, @l: if @l = 'Information' then 'Info' else @l, @x, ..@p} }\n"

However we'd like to map the other log levels to short-hands as well. Such as Warning to Warn etc. How would we go about adding multiple if-else branches to this expression?

Solution

  • The answer is surprisingly simple actually. Multiple branches can be done exactly like one might expect:

    "{ {@t, @m, @r, @l: if @l = 'Information' then 'Info' 
    else if @l = 'Warning' then 'Warn' else @l, @x, ..@p} }\n"