validator

I'm aware of this as well as go(lang)'s https://github.com/go-playground/validator, so you are right, I'm wondering about a more implicit validator like what Pydantic does when a value is assigned, versus an explicit call to validate().

validator has worked well for me, but it doesn't operate on files, rather it validates the structs after unmarshaling. https://pkg.go.dev/github.com/go-playground/validator/v10

Hello HN! go-playground/validator¹ is probably the most ubiquitous validation library in Go codebases. As much as it's flexible and neat, it's sometimes a PITA to iterate — I have to setup a whole new Go project² to just test some tags. Hence, I made a WASM³ driven online playground for the same! You can find it here: https://apps.abhijithota.me/go-validator-playground/ You can find the code and more details on the GitHub repo: https://github.com/abhijit-hota/go-validator-playground 1: https://pkg.go.dev/github.com/go-playground/validator/v10 2: Still waiting for a good Go REPL 3: There is an obvious drawback of loading the 6 MB WASM binary upfront over just using a HTTP server but hey, this a half-serious experiment!

A different language, most likely. I'd use Python for this if the work being done isn't too CPU-intensive and I can afford to make big tradeoffs. If you want to do data validation like this but for something with better performance while still retaining the benefits of a high-level GC'd language, then I'd try something like https://github.com/go-playground/validator for Go.

For json unmarshalling of structs at least, I've become a pretty big fan of the validator library from the go playground: github.com/go-playground/validator/v10 It uses struct tags to validate the struct and is quite extensive. https://godoc.org/gopkg.in/go-playground/validator.v10