处理不同类型的Golang处理程序
这些是我在研究gorilla/mux时在网上发现的模式中的应用处理程序。它们是满足http.Handler的结构的一部分。如果您注意到,以下两个块完全相同。实际上,它们可以作为字符串传递“variant”(“flow”或“process”)处理不同类型的Golang处理程序,go,dry,Go,Dry,这些是我在研究gorilla/mux时在网上发现的模式中的应用处理程序。它们是满足http.Handler的结构的一部分。如果您注意到,以下两个块完全相同。实际上,它们可以作为字符串传递“variant”(“flow”或“process”) func CreateFlow(a *AppContext, w http.ResponseWriter, r *http.Request) (int, error) { highest, code, err := a.Create("flow",
func CreateFlow(a *AppContext, w http.ResponseWriter, r *http.Request) (int, error) {
highest, code, err := a.Create("flow", r)
if code != 200 || err != nil {
return code, err
}
b := new(bytes.Buffer)
json.NewEncoder(b).Encode(struct {
Highest int `json:"id"`
}{highest})
w.Header().Set("Content-Type", "application/json")
w.Write(b.Bytes())
return 200, nil
}
func CreateProcess(a *AppContext, w http.ResponseWriter, r *http.Request) (int, error) {
highest, code, err := a.Create("process", r)
if code != 200 || err != nil {
return code, err
}
b := new(bytes.Buffer)
json.NewEncoder(b).Encode(struct {
Highest int `json:"id"`
}{highest})
w.Header().Set("Content-Type", "application/json")
w.Write(b.Bytes())
return 200, nil
}
但是,以下两个块不仅需要字符串,还需要关联类型的变量(“Flow”和“Process”)来成功地解组我从ElasticSearch获得的命中。除此之外,它们是相同的代码
func GetFlow(a *AppContext, w http.ResponseWriter, r *http.Request) (int, error) {
hit, code, err := a.GetByID("flow", mux.Vars(r)["id"], r)
if code != 200 {
return code, err
}
var flow Flow
err = json.Unmarshal(*hit.Source, &flow)
if err != nil {
return 500, err
}
flow.ESID = hit.Id
b := new(bytes.Buffer)
json.NewEncoder(b).Encode(flow)
w.Header().Set("Content-Type", "application/json")
w.Write(b.Bytes())
return 200, nil
}
func GetProcess(a *AppContext, w http.ResponseWriter, r *http.Request) (int, error) {
hit, code, err := a.GetByID("process", mux.Vars(r)["id"], r)
if code != 200 {
return code, err
}
var process Process
err = json.Unmarshal(*hit.Source, &process)
if err != nil {
return 500, err
}
process.ESID = hit.Id
b := new(bytes.Buffer)
json.NewEncoder(b).Encode(process)
w.Header().Set("Content-Type", "application/json")
w.Write(b.Bytes())
return 200, nil
}
我不知道当涉及到一个声明的类型时,如何在golang中推广这种行为。这些处理程序也都在同一个包中,因为我认为它们都在完成类似的任务。我很清楚地在代码中重复我自己,但我需要关于如何改进的建议。我已经走过了“一点复制比一点依赖要好”的历程,但我害怕,因为“反射永远不清晰”
下面是一个主要使用这些函数之一的声明示例
api.Handle("/flow/{id:[0-9]+}", handlers.AppHandler{context, handlers.GetFlow}).Methods("GET")
您可以通过传入必要类型的示例来完成此操作,方法与
Unmarshal
完成此操作的方法相同:
func GetFlow(a *AppContext, w http.ResponseWriter, r *http.Request) (int, error) {
return GetThing(a,w,r,"flow",new(Flow))
}
func GetProcess(a *AppContext, w http.ResponseWriter, r *http.Request) (int, error) {
return GetThing(a,w,r,"process",new(Process))
}
func GetThing(a *AppContext, w http.ResponseWriter, r *http.Request, t string, ob Elastible{}) (int, error) {
hit, code, err := a.GetByID(t, mux.Vars(r)["id"], r)
if code != 200 {
return code, err
}
err = json.Unmarshal(*hit.Source, ob)
if err != nil {
return 500, err
}
ob.SetESID(hit.Id)
b := new(bytes.Buffer)
json.NewEncoder(b).Encode(ob)
w.Header().Set("Content-Type", "application/json")
w.Write(b.Bytes())
return 200, nil
}
type Elastible interface {
SetESID(id ESIDType) // whatever type ESID is, not clear from example
}
func (f *Flow) SetESID(id ESIDType) {
f.ESID = id
}
这段代码未经测试(因为我没有struct def或其他依赖代码),但我希望它能让人明白这一点。好的,我提出了一个解决方案,它将为您提供最大的代码重用和最小的代码复制。在我看来,这是迄今为止最通用的解决方案。我们还将考虑由给出的答案来完成解决方案。您只需定义一个高阶函数
CreateHandler
,该函数将返回具有以下签名的函数:
func(*AppContext,http.ResponseWriter,http.Request)(int,error)
此签名是要用作mux端点的处理程序的实际签名。解决方案包括定义一个处理程序类型,该类型是一个具有三个字段的结构:
•handlerType
:将其视为值为“CREATE”
或“GET”
的枚举。这将决定您粘贴在问题中的两块代码中我们应该使用哪一块
•handlerActionName
:这将告诉“创建”
或“获取”
哪些是可弹性使用的。值应该是“flow”
或“process”
•elastible
:这将是具有SetESID
功能的接口类型elastible
。我们将使用它将流
或流程
类型发送到处理程序
。因此,流
和过程
都应该满足我们的接口。
这将使解决方案更加通用,只调用handler.elastible.SetESID()
,我们将插入ESID,而不管“elastible”中的底层类型是“Flow”还是“Process”
我还定义了一个sendResponse(响应接口{})
函数,我们将继续使用它来发送响应。它使用闭包获取whttp.ResponseWriter
<代码>响应
因此可以是任何内容,例如
struct {
Highest int `json:"id"`
}{highest}
或流
或过程
。这也将使该函数成为通用函数
现在,完整的解决方案是
// This is the type that will be used to build our handlers.
type Handler struct {
handlerType string // Can be "CREATE" or "GET"
handlerActionName string // Can be "flow" or "process"
elastible Elastible // Can be *Flow or *Process
}
// Your ESID Type.
type ESIDType string
// Solution proposed by https://stackoverflow.com/users/7426/adrian.
type Elastible interface {
SetESID(id ESIDType)
}
// Make the Flow and Process pointers implement the Elastible interface.
func (flow *Flow) SetESID(id ESIDType) {
flow.ESID = id
}
func (process *Process) SetESID(id ESIDType) {
process.ESID = id
}
// Create a Higher Order Function which will return the actual handler.
func CreateHandler(handler Handler) func(*AppContext, http.ResponseWriter, http.Request) (int, error) {
return func(a *AppContext, w http.ResponseWriter, r http.Request) (int, error) {
// Define a sendResponse function so that we may not need to copy paste it later.
// It captures w using closure and takes an interface argument that we use to call .Encode() with.
sendResponse := func(response interface{}) (int, error) {
b := new(bytes.Buffer)
json.NewEncoder(b).Encode(response)
w.Header().Set("Content-Type", "application/json")
w.Write(b.Bytes())
return 200, nil
}
// Define these variables beforehand since we'll be using them
// in both the if and else block. Not necessary really.
var code int
var err error
// Check the handlerType. Is it create or get?
if handler.handlerType == "CREATE" {
var highest int
// Creates the thing using handler.handlerActionName which may be "flow" or "process"
highest, code, err = a.Create(handler.handlerActionName, r)
if code != 200 || err != nil {
return code, err
}
// Send the response using the above defined function and return.
return sendResponse(struct {
Highest int `json:"id"`
}{highest})
} else {
// This is GET handlerType.
var hit HitType
// Get the hit using again the handler.handlerActionName which may be "flow" or "process"
hit, code, err = a.GetByID(handler.handlerActionName, mux.Vars(r)["id"], r)
if code != 200 || err != nil {
return code, err
}
// Do the un-marshalling.
err = json.Unmarshal(*hit.Source, ob)
if err != nil {
return 500, err
}
// We have set the handler.elastible to be an interface type
// which will have the SetESID function that will set the ESID in the
// underlying type that will be passed on runtime.
// So the ESID will be set for both the Flow and the Process types.
// This interface idea was given inside an earlier answer by
// https://stackoverflow.com/users/7426/adrian
handler.elastible.SetESID(hit.id)
return sendResponse(handler.elastible)
}
}
}
您可以使用以下代码设置mux端点
// This was your first function. "CreateFlow"
api.Handle("/createFlow/{id:[0-9]+}", handlers.AppHandler{
context, CreateHandler(Handler{
elastible: &Flow{},
handlerActionName: "flow",
handlerType: "CREATE",
}),
}).Methods("GET")
// This was your second function. "CreateProcess"
api.Handle("/createProcess/{id:[0-9]+}", handlers.AppHandler{
context, CreateHandler(Handler{
elastible: &Process{},
handlerActionName: "process",
handlerType: "CREATE",
}),
}).Methods("GET")
// This was your third function. "GetFlow"
api.Handle("/getFlow/{id:[0-9]+}", handlers.AppHandler{
context, CreateHandler(Handler{
elastible: &Flow{},
handlerActionName: "flow",
handlerType: "GET",
}),
}).Methods("GET")
// This was your fourth function. "GetProcess"
api.Handle("/getProcess/{id:[0-9]+}", handlers.AppHandler{
context, CreateHandler(Handler{
elastible: &Process{},
handlerActionName: "process",
handlerType: "GET",
}),
}).Methods("GET")
希望有帮助 太棒了。谢谢你的回复。我会在实施后更新。非常感谢您的详细回复。我将尝试实现您的建议(Adrian的超集),然后再回复您。为了简单起见,我省略了其他REST调用,有删除和必要的选项。也得到了一个大集。我将花一些时间来尝试和概括。阿德里安的解决方案似乎更简单,更容易理解/维护。在这里更通用似乎是以复杂性/可读性为代价的,除非你真的需要,否则IMO不值得。当然,99%的时间雅格尼原则适用:-)雅格尼原则将适用于如果我得到这个项目的报酬;)