binding
binding
binding 中间件为 Flame 实例提供请求数据绑定和验证服务，支持的数据格式包括 Form、Multipart Form、JSON 和 YAML。
你可以在 GitHub 上阅读该中间件的源码或通过 pkg.go.dev 查看 API 文档。
下载安装
go get github.com/flamego/binding用法示例
本小结仅展示 binding 中间件的相关用法，如需了解验证模块的用法请移步
validator 的文档。绑定对象自身会被注入到请求上下文中以供后续的处理器使用，并额外提供 binding.Errors 用于错误传递。
禁止传递绑定对象的指针以确保每个处理器都能够获得对象的全新副本，以及避免潜在的副作用而导致的意外错误。
Form
binding.Form 会将请求数据以 application/x-www-form-urlencoded 的编码格式将其解析到绑定对象上，binding.Options 可以被用于配置该函数的行为。
绑定对象内的字段需要使用结构体标签 form 来表示与请求数据之间的绑定关系：
package main
import (
"fmt"
"net/http"
"github.com/flamego/binding"
"github.com/flamego/flamego"
"github.com/flamego/template"
"github.com/flamego/validator"
)
type User struct {
FirstName string `form:"first_name" validate:"required"`
LastName string `form:"last_name" validate:"required"`
Age int `form:"age" validate:"gte=0,lte=130"`
Email string `form:"email" validate:"required,email"`
Hashtags []string `form:"hashtag"`
}
func main() {
f := flamego.Classic()
f.Use(template.Templater())
f.Get("/", func(t template.Template) {
t.HTML(http.StatusOK, "home")
})
f.Post("/", binding.Form(User{}), func(w http.ResponseWriter, form User, errs binding.Errors) {
if len(errs) > 0 {
var err error
switch errs[0].Category {
case binding.ErrorCategoryValidation:
err = errs[0].Err.(validator.ValidationErrors)[0]
default:
err = errs[0].Err
}
w.WriteHeader(http.StatusBadRequest)
_, _ = w.Write([]byte(fmt.Sprintf("Oops! Error occurred: %v", err)))
return
}
w.WriteHeader(http.StatusOK)
w.Write([]byte(fmt.Sprintf("User: %#+v", form)))
})
f.Run()
}Multipart Form
binding.MultipartForm 会将请求数据以 multipart/form-data 的编码格式将其解析到绑定对象上，binding.Options 可以被用于配置该函数的行为。
绑定对象内的字段需要使用结构体标签 form 来表示与请求数据之间的绑定关系，用于存储上传文件的字段则必须声明为 *multipart.FileHeader 类型：
package main
import (
"fmt"
"mime/multipart"
"net/http"
"github.com/flamego/binding"
"github.com/flamego/flamego"
"github.com/flamego/template"
"github.com/flamego/validator"
)
type User struct {
FirstName string `form:"first_name" validate:"required"`
LastName string `form:"last_name" validate:"required"`
Avatar *multipart.FileHeader `form:"avatar"`
}
func main() {
f := flamego.Classic()
f.Use(template.Templater())
f.Get("/", func(t template.Template) {
t.HTML(http.StatusOK, "home")
})
f.Post("/", binding.MultipartForm(User{}), func(w http.ResponseWriter, form User, errs binding.Errors) {
if len(errs) > 0 {
var err error
switch errs[0].Category {
case binding.ErrorCategoryValidation:
err = errs[0].Err.(validator.ValidationErrors)[0]
default:
err = errs[0].Err
}
w.WriteHeader(http.StatusBadRequest)
_, _ = w.Write([]byte(fmt.Sprintf("Oops! Error occurred: %v", err)))
return
}
w.WriteHeader(http.StatusOK)
w.Write([]byte(fmt.Sprintf("User: %#+v", form)))
})
f.Run()
}JSON
binding.JSON 会将请求数据以 application/json 的编码格式将其解析到绑定对象上，binding.Options 可以被用于配置该函数的行为。
绑定对象内的字段需要使用结构体标签 json 来表示与请求数据之间的绑定关系：
package main
import (
"fmt"
"net/http"
"github.com/flamego/binding"
"github.com/flamego/flamego"
"github.com/flamego/validator"
)
type Address struct {
Street string `json:"street" validate:"required"`
City string `json:"city" validate:"required"`
Planet string `json:"planet" validate:"required"`
Phone string `json:"phone" validate:"required"`
}
type User struct {
FirstName string `json:"first_name" validate:"required"`
LastName string `json:"last_name" validate:"required"`
Age uint8 `json:"age" validate:"gte=0,lte=130"`
Email string `json:"email" validate:"required,email"`
Addresses []*Address `json:"addresses" validate:"required,dive,required"`
}
func main() {
f := flamego.Classic()
f.Post("/", binding.JSON(User{}), func(w http.ResponseWriter, form User, errs binding.Errors) {
if len(errs) > 0 {
var err error
switch errs[0].Category {
case binding.ErrorCategoryValidation:
err = errs[0].Err.(validator.ValidationErrors)[0]
default:
err = errs[0].Err
}
w.WriteHeader(http.StatusBadRequest)
_, _ = w.Write([]byte(fmt.Sprintf("Oops! Error occurred: %v", err)))
return
}
w.WriteHeader(http.StatusOK)
w.Write([]byte(fmt.Sprintf("User: %#+v", form)))
})
f.Run()
}YAML
binding.YAML 会将请求数据以 application/yaml 的编码格式将其解析到绑定对象上，binding.Options 可以被用于配置该函数的行为。
绑定对象内的字段需要使用结构体标签 yaml 来表示与请求数据之间的绑定关系：
package main
import (
"fmt"
"net/http"
"github.com/flamego/binding"
"github.com/flamego/flamego"
"github.com/flamego/validator"
)
type Address struct {
Street string `yaml:"street" validate:"required"`
City string `yaml:"city" validate:"required"`
Planet string `yaml:"planet" validate:"required"`
Phone string `yaml:"phone" validate:"required"`
}
type User struct {
FirstName string `yaml:"first_name" validate:"required"`
LastName string `yaml:"last_name" validate:"required"`
Age uint8 `yaml:"age" validate:"gte=0,lte=130"`
Email string `yaml:"email" validate:"required,email"`
Addresses []*Address `yaml:"addresses" validate:"required,dive,required"`
}
func main() {
f := flamego.Classic()
f.Post("/", binding.YAML(User{}), func(w http.ResponseWriter, form User, errs binding.Errors) {
if len(errs) > 0 {
var err error
switch errs[0].Category {
case binding.ErrorCategoryValidation:
err = errs[0].Err.(validator.ValidationErrors)[0]
default:
err = errs[0].Err
}
w.WriteHeader(http.StatusBadRequest)
_, _ = w.Write([]byte(fmt.Sprintf("Oops! Error occurred: %v", err)))
return
}
w.WriteHeader(http.StatusOK)
w.Write([]byte(fmt.Sprintf("User: %#+v", form)))
})
f.Run()
}本地化验证错误消息
如果你的 Web 应用支持多语言，那么必然也希望能够提供本地化的错误消息给你的用户。
下面提供了一个可以在浏览器中把玩的示例来帮助你实现独居一格的本地化错误消息：
$ tree .
.
├── locales
│ ├── locale_en-US.ini
│ └── locale_zh-CN.ini
├── templates
│ └── home.tmpl
├── go.mod
├── go.sum
└── main.go