紧急：接口转换：Obj不是ObjInterface：缺少方法X

At the moment, I'm stuck in this code : https://play.golang.org/p/r_HEVmpOuD

package main

import "fmt"

type (
    Collection struct {
        Id string
    }
    CollectionInterface interface {
        Process(...string)
    }
)

func (this *Collection) Process(params ...string) {
    this.Id = "ok"

}

func testfunc(input interface{}) CollectionInterface {
    inputCol := input.(CollectionInterface)
    inputCol.Process()
    return inputCol
}

func makeInterface(input interface{}) interface{} {
    return input
}

func main() {
    test := Collection{Id: "ya"}
    test.Process()
    testInt := makeInterface(test)

    test0 := testInt.(CollectionInterface)
    test1 := testfunc(test0)
    fmt.Println(test1)
}

I'm just wondering how can I convert the interface{} into CollectionInterface without changing the "Process" function into a static function?

You are doing it wrong. I make little modification to fix it. Let me know if you have question.

https://play.golang.org/p/SEesgVhXt8

Change this line test := Collection{Id: "ya"} to this test := &Collection{Id: "ya"}. The interface is implemented for type *Collection; not Collection.