英文:
Passing in parameters to a http.HandlerFunc
问题
我正在使用Go语言内置的http服务器和pat来响应一些URL：
mux.Get("/products", http.HandlerFunc(index))
func index(w http.ResponseWriter, r *http.Request) {
// 做一些事情。
}
我需要向这个处理函数传递一个额外的参数 - 一个接口。
func (api Api) Attach(resourceManager interface{}, route string) {
// 将典型的REST操作应用于Mux。
// 例如：Product - 对应 /products
mux.Get(route, http.HandlerFunc(index(resourceManager)))
// 例如：Product ID: 1 - 对应 /products/1
mux.Get(route+"/:id", http.HandlerFunc(show(resourceManager)))
}
func index(w http.ResponseWriter, r *http.Request, resourceManager interface{}) {
managerType := string(reflect.TypeOf(resourceManager).String())
w.Write([]byte(fmt.Sprintf("%v", managerType)))
}
func show(w http.ResponseWriter, r *http.Request, resourceManager interface{}) {
managerType := string(reflect.TypeOf(resourceManager).String())
w.Write([]byte(fmt.Sprintf("%v", managerType)))
}
如何向处理函数传递额外的参数？
英文:
I'm using Go's built in http server and pat to respond to some URLs:
mux.Get("/products", http.HandlerFunc(index))
func index(w http.ResponseWriter, r *http.Request) {
// Do something.
}
I need to pass in an extra parameter to this handler function - an interface.
func (api Api) Attach(resourceManager interface{}, route string) {
// Apply typical REST actions to Mux.
// ie: Product - to /products
mux.Get(route, http.HandlerFunc(index(resourceManager)))
// ie: Product ID: 1 - to /products/1
mux.Get(route+"/:id", http.HandlerFunc(show(resourceManager)))
}
func index(w http.ResponseWriter, r *http.Request, resourceManager interface{}) {
managerType := string(reflect.TypeOf(resourceManager).String())
w.Write([]byte(fmt.Sprintf("%v", managerType)))
}
func show(w http.ResponseWriter, r *http.Request, resourceManager interface{}) {
managerType := string(reflect.TypeOf(resourceManager).String())
w.Write([]byte(fmt.Sprintf("%v", managerType)))
}
How can I send in an extra paramter to the handler function?
答案1
得分: 16
你可以通过使用闭包来实现你想要的功能。
将func index()更改为以下内容（未经测试）：
func index(resourceManager interface{}) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
managerType := string(reflect.TypeOf(resourceManager).String())
w.Write([]byte(fmt.Sprintf("%v", managerType)))
}
}
然后对func show()做同样的更改。
英文:
You should be able to do what you wish by using closures.
Change func index() to the following (untested):
func index(resourceManager interface{}) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
managerType := string(reflect.TypeOf(resourceManager).String())
w.Write([]byte(fmt.Sprintf("%v", managerType)))
}
}
And then do the same to func show()
答案2
得分: 8
另一种选择是直接使用实现了http.Handler接口的类型，而不仅仅使用函数。例如：
type IndexHandler struct {
resourceManager interface{}
}
func (ih IndexHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
managerType := string(reflect.TypeOf(ih.resourceManager).String())
w.Write([]byte(fmt.Sprintf("%v", managerType)))
}
...
mux.Get(route, IndexHandler{resourceManager})
如果你想将ServeHTTP处理方法重构为多个方法，这种模式可能会很有用。
英文:
Another option is to use types implementing http.Handler directly rather than only using functions. For example:
type IndexHandler struct {
resourceManager interface{}
}
func (ih IndexHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
managerType := string(reflect.TypeOf(ih.resourceManager).String())
w.Write([]byte(fmt.Sprintf("%v", managerType)))
}
...
mux.Get(route, IndexHandler{resourceManager})
This kind of pattern can be useful if you want to refactor your ServeHTTP handler method into multiple methods.
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