GO中运行时类型的结构的新实例 [英] New instance of struct from the type at runtime in GO
问题描述
我试图在运行时使用类型(reflect.TypeOf)来创建结构的新实例。我在StackOverflow上关注了这个线程如何在Go中运行时从Type中创建一个新的实例?。这是我的实现(也在 http://play.golang.org/p/BtX0d5Ytu8 ): 由于某些原因,我总是会得到空的struct。我无法设置字段或修改。有人可能会提出什么问题吗? 我检查了您的代码。当你使用reflect创建一个类型时,你得到了一个 检查代码 I am trying to create new instance of a struct, using it's type (reflect.TypeOf) at runtime. I have followed this thread on StackOverflow How do you create a new instance of a struct from it's Type at runtime in Go?. Here is my implementation (also at http://play.golang.org/p/BtX0d5Ytu8): For some reason, I always get empty struct. I am unable to set fields or modify. Can someone suggest what is wrong? i reviewed your code. when you new a type with reflect, you got a value in check the code
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$ b $ pre $ $ $ $ $
$ f $ $
$反映
编码/ json
字节
)
类型UserInfo结构{
电子邮件字符串`json:email`
FullName字符串`json:name`
ID字符串`json:_id`
}
func main(){
fmt.Println( Hello,playground)
db:= DBEngine {}
db.DB = make(map [string] [] byte)
db.Register(UserInfo {})
db.Put(142321,UserInfo {jdoe@acme.com,John Doe,142321})
ret:= db.Get(142321 )
fmt.Println(TypeOf(ret):,reflect.TypeOf(ret))
fmt.Println(ValueOf(ret):,reflect.ValueOf(ret))
fmt.Println(Value:,ret)
}
类型DBEngine结构体{
模板接口{}
DB map [string] [] byte
$ b $ func(db * DBEngine)Register(v interface {}){
db.Template = v
}
// Set用户定义的对象
func(db * DBEngine)Put(key string,v interface {}){
res,_:= json.Marshal(v)
db.DB [key] = res
}
//返回用户定义的对象
func(db * DBEngine)获取(键字符串)接口{} {
解码器:= json.NewDecoder bytes.NewReader(db.DB [键]));
fmt.Println(Value [] byte:,string(db.DB [key]))
ret:= reflect.New(reflect.TypeOf(db.Template))。Elem()
fmt.Println(reflect.TypeOf(db.Template),ret)
decoder.Decode(ret)
return ret.Interface()
}
Value
类型的值,需要调用 Interface()
来获得新生成的值的接口
http://play.golang.org/p/CHWSV8EG7D package main
import (
"fmt"
"reflect"
"encoding/json"
"bytes"
)
type UserInfo struct {
Email string `json:"email"`
FullName string `json:"name"`
ID string `json:"_id"`
}
func main() {
fmt.Println("Hello, playground")
db := DBEngine{}
db.DB = make(map[string][]byte)
db.Register(UserInfo{})
db.Put("142321", UserInfo{"jdoe@acme.com", "John Doe", "142321"})
ret := db.Get("142321")
fmt.Println("TypeOf(ret):", reflect.TypeOf(ret))
fmt.Println("ValueOf(ret):", reflect.ValueOf(ret))
fmt.Println("Value:", ret)
}
type DBEngine struct {
Template interface{}
DB map[string][]byte
}
func (db *DBEngine) Register(v interface{}) {
db.Template = v
}
//Set User defined object
func (db *DBEngine) Put(key string, v interface{}) {
res, _ := json.Marshal(v)
db.DB[key] = res
}
//Return user defined object
func (db *DBEngine) Get(key string) interface{} {
decoder := json.NewDecoder(bytes.NewReader(db.DB[key]));
fmt.Println("Value []byte:", string(db.DB[key]))
ret := reflect.New(reflect.TypeOf(db.Template)).Elem()
fmt.Println(reflect.TypeOf(db.Template), ret)
decoder.Decode(ret)
return ret.Interface()
}
Value
type, need to call Interface()
to get the interface of that new generated value