https://pkg.go.dev/github.com/go-playground/validator/v10#readme-baked-in-validations

• min 最小
• max 最大
• len 长度限制
• gt 大于
• eq 等于
• ne 不等于
• eqfield 与某个字段值一样
• nefield 与某个字段值不一样

package main

import (
	"net/http"

	"github.com/gin-gonic/gin"
)

type UserInfo struct {
	UserName  string `json:"username" binding:"required,min=4,max=6"`
	Age       int    `json:"age" binding:"gt=18,lte=120"`
	Password  string `json:"password" binding:"required"`
	Password2 string `json:"password2" binding:"required,eqfield=Password"`
}

// 结构体中写json
func validation(c *gin.Context) {
	var user UserInfo
	err := c.ShouldBindJSON(&user)
	if err != nil {
		c.JSON(http.StatusBadRequest, gin.H{"msg": err.Error()})
	} else {
		c.JSON(http.StatusOK, user)
	}
}

func main() {
	router := gin.Default()
	router.POST("/validation", validation)
	router.Run("localhost:9999")
}