go-playground/validator

Hello, I'm new to this library and have a question on validation for specific strings.

Question
Which way is good to validate specific string such as some status string defined like this ?

I need to apply the same type validation to multiple places.

const (
    StatusSuccess = "success"
    StatusFail = "fail"
    StatusProcessing = "processing"
)

var validStatusList = []string{
    StatusSuccess,
    StatusFail,
    StatusProcessing,
}

Background
I found 2 ways to do it using struct tag or custom validation.
I'm wondering costome valiation is better for the case we would like to use variables for validation in my current understanding because in struct tag way like the following, the strings needd to be hardcoded in struct tag.

type SomeStruct struct {
    status string `form:"status" json:"status" binding:"required,oneof=success fail processing"`
}