golang，如何在simplejson中解码json数组的项目？

Question

incoming String is:

     {"status_list":[
         {"m_id":70,"m_status":"OK","m_status_code":200,"reported":false},
         {"m_id":71,"m_status":"Send Message Over Time","m_status_code":800,"reported":false},
         {"m_id":72,"m_status":"OK","m_status_code":200,"reported":false},
         {"m_id":73,"m_status":"OK","m_status_code":200,"reported":false}
         ]
      }

How can I get the m_status field of the last status element?

The way I am using is

import github.com/bitly/go-simplejson"

....
jsonRequest, _ := simplejson.NewJson([]byte(incommingString))
mArray := jsonRequest.Get("status_list").MustArray()
mItem := mArray[3]
fmt.printf("mItem: %")
m3StatusCode := mItem["m_status_code"]   //<---<< Can't compile

I got:

invalid operation: mItem["m_status_code"] (type interface {} does not support indexing)

If I remove last line code. I can print out mItem as

mItem: : map[m_id:73 m_status:OK m_status_code:200 reported:%!s(bool=false)]

QUESTION: How can I fetch m_status_code value?

Answer 1

You will have to do a type assertion first.

m, ok := mItem.(map[string]interface{})
if(!ok){
    fmt.Println("Invalide data")
}

fmt.Println(m["m_status_code"])

This is because mItem is not actually a map. Its an interface{}. simplejson's MustArray returns a []interface{}.

So you have to assert that the value stored in mItem is of a type you can use an index m_status_code on.