英文:
How to avoid code duplication in router handling code
问题
我有一个大型路由器：
router.HandleFunc("/tags", controllers.GetTags)
router.HandleFunc("/tags/items/{tagId}", controllers.GetTaggedItemsByTagId).Methods("GET")
// ...
每个函数的结构如下：
func GetTags(w http.ResponseWriter, r *http.Request) {
tags, err := (&postgres.TagsService{}).GetTags()
if err != nil {
log.Println(err)
w.WriteHeader(500)
} else {
w.Header().Add("Content-Type", "application/json")
resp, _ := json.Marshal(tags)
w.Write(resp)
}
}
func GetTaggedItemsByTagId(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
tagId, err := strconv.Atoi(vars["tagId"])
items, err := (&postgres.TagsService{}).GetTaggedItemsByTagId(tagId)
if err != nil {
log.Println(err)
w.WriteHeader(500)
} else {
w.Header().Add("Content-Type", "application/json")
resp, _ := json.Marshal(items)
w.Write(resp)
}
}
在每个函数中，我从数据库获取数据，将结果序列化为 json，然后返回给客户端。
我需要一些方法来避免代码重复。类似于：
func Handler(err error, data object) {
if err != nil {
log.Println(err)
w.WriteHeader(500)
} else {
w.Header().Add("Content-Type", "application/json")
resp, _ := json.Marshal(object)
w.Write(resp)
}
}
由于Go是一种强类型语言，我不能这样做。在这种情况下，Go中有什么最好的方法来避免代码重复？
英文:
I have a big router:
router.HandleFunc("/tags", controllers.GetTags)
router.HandleFunc("/tags/items/{tagId}", controllers.GetTaggedItemsByTagId).Methods("GET")
// ...
Each of such functions looks like:
func GetTags(w http.ResponseWriter, r *http.Request) {
tags, err := (&postgres.TagsService{}).GetTags()
if err != nil {
log.Println(err)
w.WriteHeader(500)
} else {
w.Header().Add("Content-Type", "application/json")
resp, _ := json.Marshal(tags)
w.Write(resp)
}
}
func GetTaggedItemsByTagId(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
tagId, err := strconv.Atoi(vars["tagId"])
items, err := (&postgres.TagsService{}).GetTaggedItemsByTagId(tagId)
if err != nil {
log.Println(err)
w.WriteHeader(500)
} else {
w.Header().Add("Content-Type", "application/json")
resp, _ := json.Marshal(items)
w.Write(resp)
}
}
In each of these functions I get the data from the database, serialize result to json and return it to client.
I need something to avoid code duplication. Something like:
func Handler(err error, data object) {
if err != nil {
log.Println(err)
w.WriteHeader(500)
} else {
w.Header().Add("Content-Type", "application/json")
resp, _ := json.Marshal(object)
w.Write(resp)
}
}
I can not do this way as Go is typed language. What is the best way in Go to avoid code duplication in this case ?
答案1
得分: 3
为每个HTTP处理程序的函数签名使用一个类型：
type HandlerFunc func(w http.ResponseWriter, req *http.Request) (interface{}, error)
然后像这样包装函数：
func WrapHandler(h HandlerFunc) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
d, err := h(w, req)
// 处理错误并发送数据
}
}
然后使用以下方式设置处理程序：
router.Get('/myroute', WrapHandler(GetTaggedItemsByTagId))
英文:
Use a type for the function signature for each of the http handlers
type HandlerFunc func(w http.ResponseWriter, req *http.Request) (interface{}, error)
Then wrap the functions like this
func WrapHandler(h HandlerFunc) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
d, err := h(w, req)
// handle errors and sending out the data
}
Then set the handlers using
router.Get('/myroute', WrapHandler(GetTaggedItemsByTagId))
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