Improve Error when required is used with bool

[rvernica]

• [x] I have looked at the documentation here first?
• [x] I have looked at the examples provided that may showcase my question here?

Package version eg. v9, v10:

v10

Issue, Question or Enhancement:

When validate:"required" is added to a field of bool type, it results in this error:

2024-08-29T10:10:45.065-0700	ERROR	runtime/proc.go:271	Error loading config: error creating config: config struct issues: [Key: 'Config.Foo.Bar' Error:Field validation for 'Bar' failed on the 'required' tag]

The error is misleading, as it seems to indicate that the field is missing from the provided configuration file. In fact, the field is fine; the required validation does not make sense for the bool type. The error should be improved to provide the correct information.

See related discussion in #142

Code sample, to showcase or reproduce:

type Foo struct {
	Bar   bool   `validate:"required"`
}

[ghosx]

try

type Foo struct {
	Bar   *bool   `validate:"required"`
}

[rvernica]

That is not the point. I don't want to use a pointer, and I understand the limitations of required on bool. The point is that the error message could be improved.

[deankarn]

@rvernica you are free to translate the error into anything you desire. This is and has been the default messaging for all validations and there are no plans to change that.

[doudouwer]

Dears, I encounter this case as well. This is my case: PublicIpAssigned bool json:"PublicIpAssigned" validate:"required" And when I let PublicIpAssigned be false, I received the Error:Field validation for 'PublicIpAssigned' failed on the 'required' tag.

It's truly confused before I read the discussion in https://github.com/go-playground/validator/issues/142. However, in my humble opinion, "false" is a meaningful value just like zero in integers and is different from "null". So I suggested that "required" should refuse the "null" case, and allow the "false" case.

Hoping to hear from ur opinions.

[daniel-uribe-sperantus]

@doudouwer Yes, it's an error but it seems that its not in the roadmap to correct it. The only workaround is by using a pointer which is not ideal, the problem is quite obvious if you use the required on an int field and send it with value 0 it will trigger the validation error when it shouldn't.

It seems that the validation is wrong and the required instead of working as a required is working an an exists/notempty. Required should check if the key exists in the JSON

[deankarn]

@daniel-uribe-sperantus this is NOT an error and working as documented.

Please read the documentation here.

Additional Context:

There is no such thing as an uninitialized variable in the Go language and unset variables get their default values, nil is also a value in Go and is not the same as uninitialized.

It seems that the validation is wrong and the required instead of working as a required is working an an exists/notempty. Required should check if the key exists in the JSON

This package does not validate JSON, XML or any other data exchange format, it validates structs and variables in Go.

If you are trying to validate the existence of a variable in any of these exchange formats, then your data structure must be representative of that fact for example in this struct:

struct {
    MyBool bool
}

This boolean only represents 2 states, true or false and if no value is present gets the data types default value false. If you wish to check the presence in the exchange format you need a third state.

The main native Go way is using a pointer to gain that...I don't love pointers like this either as they're unwieldy and error prone but there are other ways also like using a custom type or an off the shelf one like Option here and registering it with the validator to know about how to handle it just like sql.NullString in the examples. The point being you need something to represent the third state.

Additionally, If it's ok to for the value to not be present in the payload and want to default it, then the third state isn't required and neither is the validation for required.

Also if you still disagree or wish the behaviour to be different for your use case you are free to register you own custom validation to suit your needs :)

I hope this helps clear up some of the confusion surrounding required.