为什么我的 Go 代码没有运行？

Question

package mainimport (    "fmt"    "github.com/ant0ine/go-json-rest"    "net/http")type App struct {    Id   string    Name string}func GetApp(w *rest.ResponseWriter, req *rest.Request) {    user := App{        Id:   req.PathParam("id"),        Name: "Antoine",    }    w.WriteJson(&user)}type MyResourceHandler struct {    rest.ResourceHandler}type ResourceController interface {    Show(w *rest.ResponseWriter, req *rest.Request)    Create(w *rest.ResponseWriter, req *rest.Request)    Update(w *rest.ResponseWriter, req *rest.Request)    Delete(w *rest.ResponseWriter, req *rest.Request)}func (self *MyResourceHandler) AddResource(name string, c ResourceController) error {    show_func := func(w *rest.ResponseWriter, r *rest.Request) {        c.Show(w, r)    }    create_func := func(w *rest.ResponseWriter, r *rest.Request) {        c.Create(w, r)    }    update_func := func(w *rest.ResponseWriter, r *rest.Request) {        c.Update(w, r)    }    delete_func := func(w *rest.ResponseWriter, r *rest.Request) {        c.Delete(w, r)    }    err := self.ResourceHandler.SetRoutes(        rest.Route{"GET", fmt.Sprintf("/%s/:id", name), show_func},        rest.Route{"POST", fmt.Sprintf("/%s", name), create_func},        rest.Route{"PUT", fmt.Sprintf("/%s/:id", name), update_func},        rest.Route{"DELETE", fmt.Sprintf("/%s/:id", name), delete_func},    )    return err}type AppController struct{}func (self *AppController) Show(w *rest.ResponseWriter, r *rest.Request) {    app := App{        Id:   r.PathParam("id"),        Name: "Antoine",    }    w.WriteJson(&app)}我已经实现了 interface 的所有四种方法ResourceController，但它告诉我：./fakeapi.go:93: cannot use controler (type AppController) as type ResourceController in function argument:    AppController does not implement ResourceController (Create method requires pointer receiver)

Answer 1

它在错误消息中： (Create method requires pointer receiver)

您已经在*AppController（指向 AppController 的指针）上定义了 Create ，但是您正在尝试使用AppController不满足接口的 。

您可能想要的解决方案是更改controler := AppController{}为controler := &AppController{}

Answer 2

正如 cthom06 所说，答案就在错误中。

错误消息的原因是您仅ResourceController在传递指针而不是值时才实现。

当您实现Show,Create等时，您使用了

func (self *AppController)...

这需要该方法获取一个指针接收器，而是AddResources被赋予了价值 的controler，而不是指针。

下面是一些示例代码来显示问题：

package main

import "fmt"

type I interface {

    Show(i int)

}

type T struct{}

func (t *T) Show(i int) {

    fmt.Println(i)

}

func CallShow(i I) {

    i.Show(32);

}

func main() {

    obj := T{}

    // CallShow(obj) // This doesn't work unless you change func (t *T) to func (t T)

    CallShow(&obj) // This works because you pass a pointer

}

Answer 3

不推荐使用“ResourceHandler”。我建议使用 v3 API：

api := rest.NewApi()

api.Use(rest.DefaultDevStack...)

router, err := rest.MakeRouter(

   // your routes here ...

)

if err != nil {

    log.Fatal(err)

}

api.SetApp(router)

log.Fatal(http.ListenAndServe(":8080", api.MakeHandler()))

Antoine - go-json-rest 作者