我想在 golang 上寫類似 CRUD 的東西。我看到像type CRUD interface {  Save(entity interface{})() // done  Update(entity interface{})() // done  Delete(entity interface{})() // done  All() []interface{} // problem is here}我有幾個(gè)模型結(jié)構(gòu)。type User struct {  Login string  Password string}type Comment struct {  UserId int64  Message string  CreatedAt int64}我有一些服務(wù)：// Struct should implement interface CRUD and use instead of interface{} User structtype UserService struct {  Txn SomeStructForContext}func (rec *UserService) Save(entity interface{}) {  user := entity.(*model.User)  // TODO operation with user}// All the same with Update and Deletefunc (rec *UserService) All() ([]interface{}) {  // TODO: I can't convert User struct array for return }我希望，它會(huì)解釋什么問(wèn)題