如何在Go中确定json对象的类型

Question

In gobyexample.com/json, a few examples show how to decode json string into typed objects or dictionary objects, which are declared as map[string]interface{}. But it assumes the result is always a dictionary.

So my question is how to determine the type of json object and what is the best practice to handle that?

Answer 1

Checkout the definition of json.Unmarshal:

func Unmarshal(data []byte, v interface{}) error

So at least you can obtain the underlying type by using reflect.

var v interface{}
json.Unmarshal([]byte(JSON_STR), &v)
fmt.Println(reflect.TypeOf(v), reflect.ValueOf(v))

And switch definitely is a better practice. I suppose below snippet

switch result := v.(type) {
case map[string]interface{}:
    fmt.Println("dict:", result)
case []interface{}:
    fmt.Println("list:", result)
default:
    fmt.Println("value:", result)
}

can basically meet your requirement.