Martini

Martini is a powerful package for quickly writing modular web applications/services in Golang.

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Getting Started

After installing Go and setting up your GOPATH, create your first .go file. We'll call it server.go.

package main

import "github.com/go-martini/martini"

func main() {
  m := martini.Classic()
  m.Get("/", func() string {
    return "Hello world!"
  })
  m.Run()
}

Then install the Martini package (go 1.1 and greater is required):

go get github.com/go-martini/martini

Then run your server:

go run server.go

You will now have a Martini webserver running on localhost:3000.

Getting Help

Join the Mailing list

Watch the Demo Video

Ask questions on Stackoverflow using the martini tag

GoDoc documentation

Features

Extremely simple to use.
Non-intrusive design.
Plays nice with other Golang packages.
Awesome path matching and routing.
Modular design - Easy to add functionality, easy to rip stuff out.
Lots of good handlers/middlewares to use.
Great 'out of the box' feature set.
Fully compatible with the http.HandlerFunc interface.

More Middleware

For more middleware and functionality, check out the repositories in the martini-contrib organization.

Classic Martini
Middleware Handlers
- Next()
Martini Env
FAQ

Classic Martini

To get up and running quickly, martini.Classic() provides some reasonable defaults that work well for most web applications:

  m := martini.Classic()
  // ... middleware and routing goes here
  m.Run()

Below is some of the functionality martini.Classic() pulls in automatically:

Request/Response Logging - martini.Logger
Panic Recovery - martini.Recovery
Static File serving - martini.Static
Routing - martini.Router

Handlers

Handlers are the heart and soul of Martini. A handler is basically any kind of callable function:

m.Get("/", func() {
  println("hello world")
})

Return Values

If a handler returns something, Martini will write the result to the current http.ResponseWriter as a string:

m.Get("/", func() string {
  return "hello world" // HTTP 200 : "hello world"
})

You can also optionally return a status code:

m.Get("/", func() (int, string) {
  return 418, "i'm a teapot" // HTTP 418 : "i'm a teapot"
})

Service Injection

Handlers are invoked via reflection. Martini makes use of Dependency Injection to resolve dependencies in a Handlers argument list. This makes Martini completely compatible with golang's http.HandlerFunc interface.

If you add an argument to your Handler, Martini will search its list of services and attempt to resolve the dependency via type assertion:

m.Get("/", func(res http.ResponseWriter, req *http.Request) { // res and req are injected by Martini
  res.WriteHeader(200) // HTTP 200
})

The following services are included with martini.Classic():

*log.Logger - Global logger for Martini.
martini.Context - http request context.
martini.Params - map[string]string of named params found by route matching.
martini.Routes - Route helper service.
http.ResponseWriter - http Response writer interface.
*http.Request - http Request.

Routing

In Martini, a route is an HTTP method paired with a URL-matching pattern. Each route can take one or more handler methods:

m.Get("/", func() {
  // show something
})

m.Patch("/", func() {
  // update something
})

m.Post("/", func() {
  // create something
})

m.Put("/", func() {
  // replace something
})

m.Delete("/", func() {
  // destroy something
})

m.Options("/", func() {
  // http options
})

m.NotFound(func() {
  // handle 404
})

Routes are matched in the order they are defined. The first route that matches the request is invoked.

Route patterns may include named parameters, accessible via the martini.Params service:

m.Get("/hello/:name", func(params martini.Params) string {
  return "Hello " + params["name"]
})

Routes can be matched with globs:

m.Get("/hello/**", func(params martini.Params) string {
  return "Hello " + params["_1"]
})

Regular expressions can be used as well:

m.Get("/hello/(?P<name>[a-zA-Z]+)", func(params martini.Params) string {
  return fmt.Sprintf ("Hello %s", params["name"])
})

Take a look at the Go documentation for more info about regular expressions syntax .

Route handlers can be stacked on top of each other, which is useful for things like authentication and authorization:

m.Get("/secret", authorize, func() {
  // this will execute as long as authorize doesn't write a response
})

Route groups can be added too using the Group method.

m.Group("/books", func(r martini.Router) {
    r.Get("/:id", GetBooks)
    r.Post("/new", NewBook)
    r.Put("/update/:id", UpdateBook)
    r.Delete("/delete/:id", DeleteBook)
})

Just like you can pass middlewares to a handler you can pass middlewares to groups.

m.Group("/books", func(r martini.Router) {
    r.Get("/:id", GetBooks)
    r.Post("/new", NewBook)
    r.Put("/update/:id", UpdateBook)
    r.Delete("/delete/:id", DeleteBook)
}, MyMiddleware1, MyMiddleware2)

Services

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 Martini instance implements the inject.Injector interface, so mapping a service is easy:

db := &MyDatabase{}
m := martini.Classic()
m.Map(db) // the service will be available to all handlers as *MyDatabase
// ...
m.Run()

Request-Level Mapping

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

func MyCustomLoggerHandler(c martini.Context, req *http.Request) {
  logger := &MyCustomLogger{req}
  c.Map(logger) // mapped as *MyCustomLogger
}

Mapping values to Interfaces

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 http.ResponseWriter with an object that wrapped it and performed extra operations, you can write the following handler:

func WrapResponseWriter(res http.ResponseWriter, c martini.Context) {
  rw := NewSpecialResponseWriter(res)
  c.MapTo(rw, (*http.ResponseWriter)(nil)) // override ResponseWriter with our wrapper ResponseWriter
}

Serving Static Files

A martini.Classic() instance automatically serves static files from the "public" directory in the root of your server. You can serve from more directories by adding more martini.Static handlers.

m.Use(martini.Static("assets")) // serve from the "assets" directory as well

Middleware Handlers

Middleware Handlers sit between the incoming http request and the router. In essence they are no different than any other Handler in Martini. You can add a middleware handler to the stack like so:

m.Use(func() {
  // do some middleware stuff
})

You can have full control over the middleware stack with the Handlers function. This will replace any handlers that have been previously set:

m.Handlers(
  Middleware1,
  Middleware2,
  Middleware3,
)

Middleware Handlers work really well for things like logging, authorization, authentication, sessions, gzipping, error pages and any other operations that must happen before or after an http request:

// validate an api key
m.Use(func(res http.ResponseWriter, req *http.Request) {
  if req.Header.Get("X-API-KEY") != "secret123" {
    res.WriteHeader(http.StatusUnauthorized)
  }
})

Next()

Context.Next() is an optional function that Middleware Handlers can call to yield the until after the other Handlers have been executed. This works really well for any operations that must happen after an http request:

// log before and after a request
m.Use(func(c martini.Context, log *log.Logger){
  log.Println("before a request")

  c.Next()

  log.Println("after a request")
})

Martini Env

Some Martini handlers make use of the martini.Env global variable to provide special functionality for development environments vs production environments. It is recommended that the MARTINI_ENV=production environment variable to be set when deploying a Martini server into a production environment.

FAQ

Where do I find middleware X?

Start by looking in the martini-contrib projects. If it is not there feel free to contact a martini-contrib team member about adding a new repo to the organization.

auth - Handlers for authentication.
binding - Handler for mapping/validating a raw request into a structure.
gzip - Handler for adding gzip compress to requests
render - Handler that provides a service for easily rendering JSON and HTML templates.
acceptlang - Handler for parsing the Accept-Language HTTP header.
sessions - Handler that provides a Session service.
strip - URL Prefix stripping.
method - HTTP method overriding via Header or form fields.
secure - Implements a few quick security wins.
encoder - Encoder service for rendering data in several formats and content negotiation.
cors - Handler that enables CORS support.
oauth2 - Handler that provides OAuth 2.0 login for Martini apps. Google Sign-in, Facebook Connect and Github login is supported.

How do I integrate with existing servers?

A Martini instance implements http.Handler, so it can easily be used to serve subtrees on existing Go servers. For example this is a working Martini app for Google App Engine:

package hello

import (
  "net/http"
  "github.com/go-martini/martini"
)

func init() {
  m := martini.Classic()
  m.Get("/", func() string {
    return "Hello world!"
  })
  http.Handle("/", m)
}

How do I change the port/host?

Martini's Run function looks for the PORT and HOST environment variables and uses those. Otherwise Martini will default to localhost:3000. To have more flexibility over port and host, use the http.ListenAndServe function instead.

  m := martini.Classic()
  // ...
  log.Fatal(http.ListenAndServe(":8080", m))

Live code reload?

gin and fresh both live reload martini apps.

Contributing

Martini is meant to be kept tiny and clean. Most contributions should end up in a repository in the martini-contrib organization. If you do have a contribution for the core of Martini feel free to put up a Pull Request.

About

Inspired by express and sinatra

Martini is obsessively designed by none other than the Code Gangsta

sundq/martini