Macaron Documentation
  • Welcome
  • Starter Guide
  • Core Concepts
  • Core Services
  • Custom Services
  • Middlewares
    • Routing
    • Templating
    • Gzip
    • Localization
    • Data Binding and Validation
    • Cache
    • Captcha
    • Session
    • Cross-Site Request Forgery
    • Embed Binary Data
    • Serving Multiple Sites
  • FAQs
  • 简体中文
    • 初学者指南
    • 核心概念
    • 核心服务
    • 自定义服务
    • 中间件和辅助模块
      • 路由模块
      • 模板引擎
      • Gzip 压缩
      • 应用本地化
      • 数据绑定与验证
      • 缓存管理(Cache)
      • 验证码服务
      • 会话管理(Session)
      • 跨域请求攻击(CSRF)
      • 嵌入二进制数据
      • 服务多个站点
    • 常见问题
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On this page
  • Global Mapping
  • Request-Level Mapping
  • Mapping values to Interfaces

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Custom Services

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Last updated 5 years ago

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Services are objects that are available to be injected into a handler's argument list. You can map a service on a Global or Request level.

Global Mapping

A Macaron instance implements the interface, so mapping a service is easy:

db := &MyDatabase{}
m := macaron.Classic()
m.Map(db) // Service will be available to all handlers as *MyDatabase
m.Get("/", func(db *MyDatabase) {
    // Operations with db.
})
m.Run()

Request-Level Mapping

Mapping on the request level can be done in a handler via :

func MyCustomLoggerHandler(ctx *macaron.Context) {
    logger := &MyCustomLogger{ctx.Req}
    ctx.Map(logger) // mapped as *MyCustomLogger
}

func main() {
    //...
    m.Get("/", MyCustomLoggerHandler, func(logger *MyCustomLogger) {
        // Operations with logger.
    })
    m.Get("/panic", func(logger *MyCustomLogger) {
        // This will panic because no logger service maps to this request.
    })
    //...
}

Mapping values to Interfaces

func WrapResponseWriter(ctx *macaron.Context) {
    rw := NewSpecialResponseWriter(ctx.Resp)
    // override ResponseWriter with our wrapper ResponseWriter
    ctx.MapTo(rw, (*http.ResponseWriter)(nil)) 
}

In this way, your code can enjoy new custom service feature without any change. Plus, allow more custom implementations of same type of services.

One of the most powerful parts about services is the ability to map a service to an interface. For instance, if you wanted to override the with an object that wrapped it and performed extra operations, you can write the following handler:

inject.Injector
*macaron.Context
http.ResponseWriter