REST API Todo

main.go

package main

import (
  "os"
  "encoding/json"
  "net/http"
  "strconv"

  "github.com/gorilla/mux"
  "github.com/gorilla/handlers"
)

type Todo struct {
  Id              int    `json:"id"`
  Description     string `json:"description"`
  Complete        bool   `json:"complete"`
}

var Todos []Todo
var Id int

func main() {

  Id = 1
  Todos = []Todo{ Todo{Id: Id, Description: "Buy Cola"} }

  r := mux.NewRouter()

  r.Handle("/todos", ListTodoHandler).Methods("GET")
  r.Handle("/todos", CreateTodoHandler).Methods("POST")
  r.Handle("/todos/{id}", UpdateTodoHandler).Methods("PUT")
  r.Handle("/todos/{id}", DeleteTodoHandler).Methods("DELETE")

  // start the server listening, and always sending back
  // the "NotImplemented" message
  http.ListenAndServe(":3000", 
    handlers.LoggingHandler(os.Stdout, r))

}

var NotImplementedHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
  w.Header().Set("Content-Type", "application/json")
  w.WriteHeader(http.StatusNotImplemented)
})

var ListTodoHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
  json.NewEncoder(w).Encode(Todos);  
})

var CreateTodoHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
  decoder := json.NewDecoder(r.Body);
  var newTodo Todo

  err := decoder.Decode(&newTodo)

  if err != nil {
    w.WriteHeader(http.StatusInternalServerError)
    return
  } 

  defer r.Body.Close()

  Id ++
  newTodo.Id = Id

  Todos = append(Todos, newTodo)

  w.WriteHeader(http.StatusCreated)
  json.NewEncoder(w).Encode(Id);  
})

func Filter(vs []Todo, f func(Todo) bool) []Todo {
  vsf := make([]Todo, 0)
  for _, v := range vs {
    if f(v) {
      vsf = append(vsf, v)
    }
  }
  return vsf
}

var UpdateTodoHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
  params := mux.Vars(r)
  id, _ := strconv.Atoi(params["id"])

  Todos = Filter(Todos, func(t Todo) bool { 
    return t.Id != id
  })

  decoder := json.NewDecoder(r.Body);
  var newTodo Todo

  err := decoder.Decode(&newTodo)

  if err != nil {
    w.WriteHeader(http.StatusInternalServerError)
    return
  } 

  defer r.Body.Close()

  newTodo.Id = id

  Todos = append(Todos, newTodo)

  w.WriteHeader(http.StatusNoContent)
})

var DeleteTodoHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
  params := mux.Vars(r)
  id, _ := strconv.Atoi(params["id"])

  Todos = Filter(Todos, func(t Todo) bool { 
    return t.Id != id
  })

  w.WriteHeader(http.StatusNoContent)
})