Validation issue #2334

dimuska139 · 2020-04-21T22:41:49Z

Description

There is no way to handle validation error If struct field has type "int" and user sends string value.

How to reproduce

package main

import (
	"fmt"
	"github.com/gin-gonic/gin"
	"github.com/go-playground/validator/v10"
	"net/http"
        "reflect"
)

func main() {
	g := gin.Default()
	g.GET("/articles", func(c *gin.Context) {
		type Paginator struct {
			Page int `form:"page" binding:"required,min=1"`
		}
		var pag Paginator
		if err := c.ShouldBindQuery(&pag); err != nil {
			errs := err.(validator.ValidationErrors)
			respErrors := make(map[string]interface{})
			for _, v := range errs {
				field, _ := reflect.TypeOf(&pag).Elem().FieldByName(v.Field())
				fieldName, _ := field.Tag.Lookup("form")
				respErrors[fieldName] = v.Tag()
			}
			c.JSON(http.StatusBadRequest, gin.H{"errors": respErrors})
			return
		}
		c.String(200, "Articles list is here")
	})
	g.Run(":9000")
}

Expectations

For example: /articles?page=1 is correct but /articles?page=stringishere throws panic. How to resolve this situation and return correct error message {"errors":"page":"Number expected"}?

Environment

go version: go1.12.7 linux/amd64
gin version (or commit ref): 1.6.2
operating system: Linux Mint

canercidam · 2020-04-22T17:29:42Z

@dimuska139 The panic comes from type assertion line:

errs := err.(validator.ValidationErrors)

interface conversion: error is *strconv.NumError, not validator.ValidationErrors

You probably need to do something like:

errs, ok := err.(validator.ValidationErrors)
if !ok {
	c.String(400, "Handle differently")
	return
}

or this, which is even better handling IMO:

switch err.(type) {
case validator.ValidationErrors:
	respErrors := make(map[string]interface{})
	for _, v := range err.(validator.ValidationErrors) {
		field, _ := reflect.TypeOf(&pag).Elem().FieldByName(v.Field())
		fieldName, _ := field.Tag.Lookup("form")
		respErrors[fieldName] = v.Tag()
	}
	c.JSON(http.StatusBadRequest, gin.H{"errors": respErrors})

case *strconv.NumError:
	c.String(400, "Handle differently")
}

dimuska139 · 2020-04-22T17:36:28Z

@canercidam yes, you are right. But this method doesn't allow to know which field has error. Because of strconv.NumError has no information about validation.

canercidam · 2020-04-22T18:34:43Z

@dimuska139 True. I understand the problem better now.

The number conversion error comes from mapForm call inside Bind() and thus it's different than the error from validate(obj). I think the solution to your problem is setting the field empty, nil or zero in these cases by changing the overall logic in this file (and not returning these errors). Then I guess validate(obj) will fail with field errors.

It should also be possible to use a different query binding in ShouldBindWith(). I guess it is hard to prefer over the other solution but you might find something that works better for your case.

dimuska139 · 2020-04-22T18:58:51Z

@canercidam I've fixed it by using thedevsaddam/govalidator before ShouldBindQuery but I think that it's not a good solution.

rules := govalidator.MapData{
    "page":      []string{"required", "numeric", "numeric_between:1,"},
    "page_size": []string{"required", "numeric", "numeric_between:1,100"},
}

type Paginator struct {
    Page     int `form:"page"`
    PageSize int `form:"page_size"`
}

var pag Paginator

opts := govalidator.Options{
    Request: c.Request,
    Data:    &pag,
    Rules:   rules,
}

v := govalidator.New(opts)
errs := v.Validate()
if len(errs) != 0 {
    c.JSON(http.StatusOK, gin.H{
        "errors": errs,
        "meta":   nil,
        "data":   nil,
    })
    return
}
c.ShouldBindQuery(&pag)

May	JUN	Jul
	30
2019	2020	2021

gin-gonic / gin

Validation issue #2334

Validation issue #2334

dimuska139 commented Apr 21, 2020

canercidam commented Apr 22, 2020 •

edited

dimuska139 commented Apr 22, 2020 •

edited

canercidam commented Apr 22, 2020 •

edited

dimuska139 commented Apr 22, 2020 •

edited

gin-gonic / gin

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Validation issue #2334

Validation issue #2334

Comments

dimuska139 commented Apr 21, 2020

Description

How to reproduce

Expectations

Environment

canercidam commented Apr 22, 2020 • edited

dimuska139 commented Apr 22, 2020 • edited

canercidam commented Apr 22, 2020 • edited

dimuska139 commented Apr 22, 2020 • edited

canercidam commented Apr 22, 2020 •

edited

dimuska139 commented Apr 22, 2020 •

edited

canercidam commented Apr 22, 2020 •

edited

dimuska139 commented Apr 22, 2020 •

edited