required_without does not work with pointers

[tbe]

Package version eg. v8, v9:

v9

Issue, Question or Enhancement:

required_without does not work with pointers

Code sample, to showcase or reproduce:

Playground: https://play.golang.org/p/5hpXOfDJU4V

package main

import (
	"fmt"
	"gopkg.in/go-playground/validator.v9"
)

type a struct {
	Field1 *string `validate:"required_without=Field2"`
	Field2 *int    `validate:"required_without=Field1"`
}

func main() {
	validate := validator.New()

	testStr := new(string)
	*testStr = "abcd"

	testInt := new(int)
	*testInt = 42

	if err := validate.Struct(a{Field1: testStr}); err != nil {
		fmt.Println(err)
	} else {
		fmt.Println("Test A OK")
	}

	if err := validate.Struct(a{Field2: testInt}); err != nil {
		fmt.Println(err)
	} else {
		fmt.Println("Test B OK")
	}

	if err := validate.Struct(a{Field1: testStr, Field2: testInt}); err != nil {
		fmt.Println(err)
	} else {
		fmt.Println("Test C OK")
	}
}

[AlexanderGrom]

Hello!
https://play.golang.org/p/lx1Qoi1HLOF

package main

import (
	"fmt"
	"gopkg.in/go-playground/validator.v9"
)

type a struct {
	Field1 string `validate:"required_with=Field2"`
	Field2 int    `validate:"required_with=Field1"`
}

func main() {
	validate := validator.New()

	// req is a pointer!
	req := &a{
		Field1: "string",
	}

	defer func() {
		if r := recover(); r != nil {
			fmt.Println("Recovered:", r)
		}
	}()

	// We get panic! (req is a pointer)
	if err := validate.Struct(req); err != nil {
		fmt.Println(err)
	} else {
		fmt.Println("Test A OK")
	}

	if err := validate.Struct(*req); err != nil {
		fmt.Println(err)
	} else {
		fmt.Println("Test B OK")
	}
}

I get panic: reflect: call of reflect.Value.FieldByName on ptr Value

fl.Parent().Kind() is a pointer if struct is a pointer.

Usually in http frameworks the request is a pointer.

var request = new(myRequest)
if err = ctx.BindJSON(request); err != nil {
	c.BadRequestError(ctx, "bad_request")
	return
}

[crathjen]

@tbe did #484 fix your issue? Because I still seem to be experiencing the problem that you identified (seeing it on the required_without_all tag rather than required_with).
Another example: https://play.golang.org/p/Gx6hh4ASKQa

package main

import (
	"gopkg.in/go-playground/validator.v9"
	"fmt"
)

func main() {
	
	v:=validator.New()
	
	result := v.Struct(foo{A: &emptystruct{}})
	if result != nil {
		fmt.Println(fmt.Sprintf("Unexpected Error: %s", result))
	}
	
	result = v.Struct(bar{A: "somevalue"})
	if result != nil {
		fmt.Println(fmt.Sprintf("Unexpected Error: %s", result))
	}
	
}

type foo struct {
	A *emptystruct `validate:"required"`
	B *emptystruct `validate:"required_without_all=A C"`
	C *emptystruct
}

type bar struct {
	A string `validate:"required"`
	B string `validate:"required_without_all=A C"`
	C string
}

type emptystruct struct {
}

gives the error

Unexpected Error: Key: 'foo.B' Error:Field validation for 'B' failed on the 'required_without_all' tag

The fact that this does not also output a failure for foo.A being required highlights the discrepancy between the behavior of required and the behavior of required_without_all

[johndww]

@leafduo @crathjen @tbe I don't think the fixed worked either.

func TestLookup(t *testing.T) {
	type Lookup struct {
		FieldA *string `json:"fieldA,omitempty" validate:"required_without=FieldB"`
		FieldB *string `json:"fieldB,omitempty" validate:"required_without=FieldA"`
	}

	fieldAValue := "1232"
	lookup := Lookup{
		FieldA: &fieldAValue,
		FieldB: nil,
	}

	assert.NoError(t, validator.New().Struct(lookup))
}

fails on 9.29.1

[renxiawang]

@johndww +1, still failing on 9.29.1.

[deankarn]

sorry that I have not been able to take a look at this, super busy with work right now.

If anyone can help with the debugging and a PR it would be very appreciated :)

[leafduo]

#484 fixed panicking when the variable to validate is pointer, as in

validator/validator_test.go

Line 8715 in 556b9da

errs = validate.Struct(&test2)

But it did not fix the problem of required_without working with pointers. Digging into the code, I've found out that the problem is in traverseField:

validator/validator.go

Lines 96 to 159 in 556b9da

	func (v *validate) traverseField(ctx context.Context, parent reflect.Value, current reflect.Value, ns []byte, structNs []byte, cf *cField, ct *cTag) {
	var typ reflect.Type
	var kind reflect.Kind
	current, kind, v.fldIsPointer = v.extractTypeInternal(current, false)
	switch kind {
	case reflect.Ptr, reflect.Interface, reflect.Invalid:
	if ct == nil {
	return
	}
	if ct.typeof == typeOmitEmpty || ct.typeof == typeIsDefault {
	return
	}
	if ct.hasTag {
	v.str1 = string(append(ns, cf.altName...))
	if v.v.hasTagNameFunc {
	v.str2 = string(append(structNs, cf.name...))
	} else {
	v.str2 = v.str1
	}
	if kind == reflect.Invalid {
	v.errs = append(v.errs,
	&fieldError{
	v: v.v,
	tag: ct.aliasTag,
	actualTag: ct.tag,
	ns: v.str1,
	structNs: v.str2,
	fieldLen: uint8(len(cf.altName)),
	structfieldLen: uint8(len(cf.name)),
	param: ct.param,
	kind: kind,
	},
	)
	return
	}
	v.errs = append(v.errs,
	&fieldError{
	v: v.v,
	tag: ct.aliasTag,
	actualTag: ct.tag,
	ns: v.str1,
	structNs: v.str2,
	fieldLen: uint8(len(cf.altName)),
	structfieldLen: uint8(len(cf.name)),
	value: current.Interface(),
	param: ct.param,
	kind: kind,
	typ: current.Type(),
	},
	)
	return
	}

// traverseField validates any field, be it a struct or single field, ensures it's validity and passes it along to be validated via it's tag options
func (v *validate) traverseField(ctx context.Context, parent reflect.Value, current reflect.Value, ns []byte, structNs []byte, cf *cField, ct *cTag) {

	var typ reflect.Type
	var kind reflect.Kind

	current, kind, v.fldIsPointer = v.extractTypeInternal(current, false)

	switch kind {
	case reflect.Ptr, reflect.Interface, reflect.Invalid:

		if ct == nil {
			return
		}

		if ct.typeof == typeOmitEmpty || ct.typeof == typeIsDefault {
			return
		}

		if ct.hasTag {
//...
			v.errs = append(v.errs,
				&fieldError{
					v:              v.v,
					tag:            ct.aliasTag,
					actualTag:      ct.tag,
					ns:             v.str1,
					structNs:       v.str2,
					fieldLen:       uint8(len(cf.altName)),
					structfieldLen: uint8(len(cf.name)),
					value:          current.Interface(),
					param:          ct.param,
					kind:           kind,
					typ:            current.Type(),
				},
			)

			return
		}
//...

According to code above, any pointer with validator other than omitempty or isdefault and has tag will throw error. Although I've found the bad code path, I don't know how to fix it, because I don't fully understand the logic. For example, how does other validators work with pointers? What does hasTag mean?

@deankarn can you shed some light?

BTW, in the test code, if errs != nil is misspelled as if errs == nil at

validator/validator_test.go

Line 8717 in 556b9da

if errs == nil {

and

validator/validator_test.go

Line 8762 in 556b9da

if errs == nil {

, which causes the bug not to be found.

[leafduo]

Maybe #510 will fix this issue?

[deankarn]

For context how other validations work with pointers is that they are dereferenced prior to validation, but since the value is nil then there's nothing to dereference.

I think another exception may be necessary like omitempty and isdefault.

I like #510 but it's unfortunately a breaking change.

[deankarn]

I released a bunch of fixes today including all required_with* functionality, please let me know if this works as expected for you now, see v9.30.0

[renxiawang]

So with the latest version, the issue is not fully resolved.
Working code: https://play.golang.org/p/PPp8OeT-2xG
Not working code: https://play.golang.org/p/scNTDSb_r4c (assigning false to a *bool breaks)

[deankarn]

I believe I've properly corrected the issues now and released in:

• https://github.com/go-playground/validator/releases/tag/v9.30.1
• https://github.com/go-playground/validator/releases/tag/v10.0.1

please let me know if this resolves your issues :)

P.S. I highly recomment updating to v10

[melonaerial]

Hello @deankarn
Do you ave any plans to add one_of functionality for required? For example, if I want to that just one of Field1 and Field2 was set, I have to write code something like this https://play.golang.org/p/tY4x6H5h8io . But this not so good hack I think. Or write required validation by my function.

[deankarn]

@melonaerial can you please open a new issue next time 🙏 it's hard discussing in a closed and unrelated thread.

I'm not 100% sure what you're trying to accomplish? doesn't required_without_all suite your use case?

[MaciejKaras]

Hi @deankarn

I'm not sure it works when you have mulitple validation tags. Please run:
https://play.golang.org/p/Aq1ebMyzXs8