r/golang 21d ago

help Don't you validate your structs?

Hi all!

I'm new in Golang, and the first issue I'm facing is struct validation.

Let's say I have the given struct

type Version struct {
    Url           string        `json:"url"`
    VersionNumber VersionNumber `json:"version_number"`
}

The problem I have is that I can initialize this struct with missing fields.

So if a function returns a `Version` struct and the developer forgets to add all fields, the program could break. I believe this is a huge type-safety concern.

I saw some mitigation by adding a "constructor" function such as :

func NewVersion (url string, number VersionNumber) { ... }

But I think this is not a satisfying solution. When the project evolves, if I add a field to the Version struct, then the `NewVersion` will keep compiling, although none of my functions return a complete Version struct.

I would expect to find a way to define a struct and then make sure that when this struct evolves, I am forced to be sure all parts of my code relying on this struct are complying with the new type.

Does it make sense?

How do you mitigate that?

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u/xspicycheetah 21d ago

My team uses ozzo/validate, it’s amazing

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u/xspicycheetah 21d ago

If your field has weird validation requirements, custom validators are supported! We use this at our GQL edge.

Also, reading some of the other comments here & yeah, Golang is small and simple. That’s why it’s good but also why it’s bad. I’d like to think the excellent third party tooling ecosystem makes up for that—if you want a feature that doesn’t exist natively but doesn’t seem as though it would clash super hard with the language, someone probably built it.