Binding time.Time with a format tag

[Rudis1261]

I am keen to use datetime_local input fields for simple projects that post a custom format to the API.

I can currently support this with custom types which formatters, and binders, a bunch of boilerplate, but it feels like for a time.Time field, it would be awesome to be able to add a tag, for instance, format:datetime:"2006-01-02T15:04", or if I wanted to for a date input field type then I could also support that simply with a tag.

Sounds like a decent idea?