[英]go: type assert of interface
I have a problem with making dynamic model of a struct. 我对构建结构的动态模型有问题。 I mean that I want to assert or cast, or just change the type of struct according to the incoming data strut.
我的意思是我想断言或强制转换,或者只是根据传入的数据strut更改结构的类型。
if sourceName
variable would be type_x
, than the type of deserializedData
should be type_x
, if type_y
, than type_y
. 如果
sourceName
变量将被type_x
,比的类型deserializedData
应type_x
,如果type_y
,比type_y
。 How to set the variable deserializedData
dynamicly for this ? 如何设置可变
deserializedData
动态地为这个?
I have this part in my code: 我的代码中有这一部分:
....
var cacheData []byte
var deserializedData models.NoaggModel
cache_err := cache.Get(string(string(sourceName) + "_" + string(t.Date)), &cacheData);
if cache_err != nil {
fmt.Println("cache_error: ", cache_err)
panic("the cache is empty")
}
err2 := json.Unmarshal([]byte(cacheData), &deserializedData)
if err2 == nil {
fmt.Println("deserialized data: " + string(sourceName), deserializedData)
}
for _, chart := range charts {
w.Name = chart.Name
if err2 == nil {
w.Data = countDataByName(sourceName, deserializedData, t.Request.Filters, string(chart.Name))
}
out <- w
}
....
How to modify it, to avoid setting models.Noagg Model
type in a strict way? 如何进行修改,以避免设置
models.Noagg Model
。严格models.Noagg Model
类型?
Creating an instance of a type dynamically during runtime can be done using the reflect package. 可以使用反射包在运行时动态创建类型的实例。 You can use a map to store the different types that you should be able to create:
您可以使用地图来存储应该创建的不同类型:
Example: 例:
package main
import (
"fmt"
"reflect"
)
type Foo struct {
Foo string
}
type Bar struct {
Bar int
}
func main() {
var sourceTypes = map[string]reflect.Type{
"foo": reflect.TypeOf(Foo{}),
"bar": reflect.TypeOf(Bar{}),
}
sourceName := "foo"
var deserializedData interface{}
deserializedData = reflect.New(sourceTypes[sourceName]).Interface()
fmt.Printf("%#v", deserializedData)
}
Output: 输出:
&main.Foo{Foo:""}
&main.Foo {富: “”}
Playground: http://play.golang.org/p/qeDA4cu5et 游乐场: http : //play.golang.org/p/qeDA4cu5et
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