decorator.go

package main

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

  "github.com/julienschmidt/httprouter"
)

func IDShouldBeInt(h httprouter.Handle, name string) httprouter.Handle {
  return CommonHeaders(func(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
      idParam := ps.ByName("yamaId")
      _, err := strconv.Atoi(idParam)
      if err != nil {
          w.Header().Set("Content-Type", "application/json; charset=UTF-8")
          w.WriteHeader(500)
          if err := json.NewEncoder(w).Encode(err); err != nil {
              return
          }
          return
      }

      h(w, r, ps)
  }, name)
}

func CommonHeaders(h httprouter.Handle, name string) httprouter.Handle {
  return Logging(func(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
      w.Header().Set("Content-Type", "application/json; charset=UTF-8")
      h(w, r, ps)
  }, name)
}