将字节数组解组到接口，然后将该接口类型强制转换为struct不起作用？

Question

I have been coding in golang for a while now. I have come across something I thought would work perfectly fine.

When I JSON Marshal a nested struct in golang I get the array of bytes, when I UnMarshal the same into an interface and convert the interface into the respective nested struct, it gives me a panic stating interface conversion: interface is map[string]interface but not the nested struct.

Please go through the link below.

https://play.golang.org/p/apdR4TKjee-

Can someone explain to me what is that I am missing?

Answer 1

When you unmarshall JSON into interface{}, it has no way to know what type you want it to use, so it defaults to map[string]interface{} as indicated in the documentation:

To unmarshal JSON into an interface value, Unmarshal stores one of these in the interface value:

...

map[string]interface{}, for JSON objects

If you want to unmarshal to a specific type, pass an instance of that type to Unmarshal:

var result sample 
err = json.Unmarshal(data,&result)