The field to be compared with the oneof values can be converted to lower case before validating the struct.

@vijsourabh as @filikos stated you could normalize the data if that's an option; here's a lib to help out with that https://github.com/go-playground/mold

If not then a custom validator is also an option.

@deankarn & @filikos, It worked, Thanks :)

This is a rather obtuse solution "downcase the value before validating" the point of the project is to add magic to model validation right? Adding another meta tag that will handle casing would be rather helpful. There are more applications to model validations that serving up 400s to a client, and using the same model across a platform is of benefit. I could accept "we are taking pull requests!" as a better answer than "downcase the value", it's essentially a non-answer.

@draper-lucid

1. Please try not to comment on closed issues unless it's also asking to be re-opened.
2. This is a rather obtuse solution is it? Depends on your use case. Sanitization of data before storing is the norm in my experience ymmv. In any case, it's not a non-answer.
3. Nobody's stopping anyone from making a PR for a new validation tag, something like case_insensitive_oneof or alike.
4. Library also allows creating and registering custom validations for you use case that's not supported by default. In fact for oneof I usually register my own custom one in order to leverage an internal map, array etc.. that holds these concrete values in the code and if any are added or removed there's no forgetting to update the struct tags.

Just another idea

Register your new validation

validate.RegisterValidation("oneof_insensitive", validateOneOfInsensitive)

Validation logic for oneof_insensitive case

func validateOneOfInsensitive(fl validator.FieldLevel) bool {
	fieldValue := fl.Field().String()
	allowedValues := strings.Split(fl.Param(), " ")

	for _, allowedValue := range allowedValues {
		if strings.EqualFold(fieldValue, allowedValue) {
			return true
		}
	}

	return false
}