@p['x'] <> 2 is false if @p['x'] is undefined #129
Description
It seems like @p['x'] <> 2 is evaluated to false if no context property x is given. I would expect an undefined value to be not equal to 2. It works if you check explicitly if x is defined.
Example code:
var logger = new Serilog.LoggerConfiguration()
.WriteTo.Logger(lc => lc
.WriteTo.Console(new ExpressionTemplate("[ALL] {@m}\n")))
// works
.WriteTo.Logger(lc => lc
.WriteTo.Console(new ExpressionTemplate("[x=2] {@m}\n"))
.Filter.ByIncludingOnly("@p['x'] = 2"))
// no output if x is undefined
.WriteTo.Logger(lc => lc
.WriteTo.Console(new ExpressionTemplate("[x<>2] {@m}\n"))
.Filter.ByIncludingOnly("@p['x'] <> 2"))
// works
.WriteTo.Logger(lc => lc
.WriteTo.Console(new ExpressionTemplate("[x<>2, def check] {@m}\n"))
.Filter.ByIncludingOnly("not IsDefined(@p['x']) or @p['x'] <> 2"))
.CreateLogger();
logger.Information("Some info, no x");
logger.ForContext("x", 2).Information("Some info, x is 2");
logger.ForContext("x", 3).Information("Some info, x is 3");
Output:
[ALL] Some info, no x
[x<>2, def check] Some info, no x
[ALL] Some info, x is 2
[x=2] Some info, x is 2
[ALL] Some info, x is 3
[x<>2] Some info, x is 3
[x<>2, def check] Some info, x is 3
Expected (at least by me):
[ALL] Some info, no x
[x<>2] Some info, no x
[x<>2, def check] Some info, no x
[ALL] Some info, x is 2
[x=2] Some info, x is 2
[ALL] Some info, x is 3
[x<>2] Some info, x is 3
[x<>2, def check] Some info, x is 3