go - 使用 Gin 框架验证 Golang 中的枚举

Question

我尝试使用 Gin 框架验证枚举在 Golang 中是否有效。

我遇到了这个解决方案:

• Use enum validation in golang with gin with custom error messages

但这种方法的缺点是每次枚举值发生变化时我们都必须手动更改硬编码值。

有没有什么方法可以通过名称作为字符串获取枚举，而无需创建映射并将其注册到类型中？

期望的结果:

package main

import "github.com/go-playground/validator"

type Status int

const (
    Single Status = iota
    Married
    Other
)

type User struct {
    Status Status `json:"status" binding:"Enum=Status"`
}

func Enum(fl validator.FieldLevel) bool {
    enumType := fl.Param() // Status
    // get `Status` by `enumType` and validate it...
    return true
}

func main() {}

Answer 1

此解决方案的方法之一可能是:

package main

import (
    "net/http"

    "github.com/gin-gonic/gin"
    "github.com/gin-gonic/gin/binding"
    "github.com/go-playground/validator/v10"
)

type Enum interface {
    IsValid() bool
}

type Status int

const (
    Single Status = iota + 1 // add + 1 otherwise validation won't work for 0
    Married
    Other
)

func (s Status) IsValid() bool {
    switch s {
    case Single, Married, Other:
        return true
    }

    return false
}

type Input struct {
    RelationshipStatus Status `json:"relationship_status" binding:"required,enum"`
}

func UpdateRelationshipStatus(context *gin.Context) {
    input := Input{}

    err := context.ShouldBindJSON(&input)
    if err != nil {
        context.JSON(http.StatusBadRequest, gin.H{"message": "enum is not valid"})
        return
    }

    context.JSON(http.StatusOK, gin.H{"message": "correct enum"})
}

func ValidateEnum(fl validator.FieldLevel) bool {
    value := fl.Field().Interface().(Enum)
    return value.IsValid()
}

func main() {
    if v, ok := binding.Validator.Engine().(*validator.Validate); ok {
        v.RegisterValidation("enum", ValidateEnum)
    }

    router := gin.Default()

    router.POST("", UpdateRelationshipStatus)

    router.Run(":3000")
}

输出:

curl \
  --request POST \
  --data '{"relationship_status": 0}' \
  http://localhost:3000/
# {"message":"enum is not valid"}

curl \
  --request POST \
  --data '{"relationship_status": 1}' \
  http://localhost:3000/
# {"message":"correct enum"}

curl \
  --request POST \
  --data '{"relationship_status": 2}' \
  http://localhost:3000/
# {"message":"correct enum"}

curl \
  --request POST \
  --data '{"relationship_status": 3}' \
  http://localhost:3000/
# {"message":"correct enum"}

curl \
  --request POST \
  --data '{"relationship_status": 4}' \
  http://localhost:3000/
# {"message":"enum is not valid"}