BeforeValidate hook

[jh125486]

Would a BeforeValidate hook be useful?

My own use case is that I'm setting up a logger with levels, which can be enumed DEBUG,INFO,WARN,ERROR.
The issue is that users are inputting level=Debug or level=debug, so I would like to normalize that input to uppercase before the Validation is run.

I can PR this in if anyone else finds it useful.

[alecthomas]

Wouldn't it be simpler to do the normalisation in UnmarshalText() for the field?

eg.

type LogLevel string

func (l *LogLevel) UnmarshalText(data []byte) error {
  level := strings.ToLower(string(data))
  ...
}

[jh125486]

I think it would.... I never had to satisfy UnmarshalText() for a type, so it completely skipped my mind.

[alecthomas]

That's usually where I do all my validation and/or normalisation. Works quite well.