如何使用反射包访问函数的返回数据？

Question

I have a function of the IndexController type:

func (this IndexController) ActionIndex() map[string]string {
    return map[string]string{"Name": "Hello from the actionIndex()!"}
}

It is used so:

routerInstance := router.Constructor(request)

controllerObject := controllers[routerInstance.GetRequestController(true)]

outputData := reflect.ValueOf(controllerObject).MethodByName(routerInstance.GetRequestAction(true)).Call([]reflect.Value{})

fmt.Println(outputData)

Now for example, how to show the Name element of outputData? I try to print so:

fmt.Println(outputData["Name"])

But program will exit with error:

# command-line-arguments
./server.go:28: non-integer array index "Name"

I will be thankful!

Answer 1

First, (v Value) Call(…) returns a []reflect.Value, so you need to index it to get your actual return value:

outputData := reflect.ValueOf(controllerObject).MethodByName(routerInstance.GetRequestAction(true)).Call([]reflect.Value{})[0]

(note the [0] at the end of the line)

From there on, you could probably do a type switch or maybe an interface conversion like outputData.(map[string]interface{}) to get a map that you can index by string.

It would help though if you would provide your entire server.go file, or maybe put it up on play.golang.org.