使用Gin框架在Golang中验证枚举

Question

我试着用Gin框架验证枚举在Golang中是否有效。

我偶然发现了这样的解决方案：

• 使用带有自定义错误消息的gin在golang中使用枚举验证

但是这种方法的缺点是硬编码值，每当枚举值发生变化时，必须手动更改。

是否有任何方法可以获得枚举的名称为字符串，而不创建和注册类型的映射？

预期结果：

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

解决这一问题的办法之一是：

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"}