Go cannot range over <my var> (type interface {})

Question

I'm in the infant stages of trying to wrap my mind around Go. At the moment, I'm simulating an API request that returns a JSON-formatted string containing an array of objects. I'm trying to figure out the most appropriate way to iterate over each record and access each field. Ultimately, each field will be written to an Excel spreadsheet, but for now I just want to print each field's key & value.

Here's what I have (I'd provide it in the Go Playground, but HTTP requests aren't supported):

    response, err := http.Get("http://go-proto.robwilkerson.org/demo.json")     failOnError(err, "Uh oh")     defer response.Body.Close()      var view []interface{}     json.NewDecoder(response.Body).Decode(&view)     log.Printf(" [x] Pulled JSON: %s", view)     for _, record := range view {         log.Printf(" [===>] Record: %s", record)          for key, val := range record {             log.Printf(" [========>] %s = %s", key, val)         }     } 

Everything works fine until the nested loop that attempts to iterate over the map that holds the properties of each record:

cannot range over record (type interface {}) 

I have two questions, I guess:

1. Is the nested loop the most effective/efficient means of accessing each property of each record?
2. What do I need to do to work around that error?

UPDATE

When I dump the data that is decoded into the view variable, this is the logged result:

[     map[id:ef14912f-8031-42b3-8c50-7aa612287534 avatar:http://placehold.it/32x32 name:Vilma Hobbs email:[email protected] phone:+1 (886) 549-3522 address:471 Dahill Road, Jacksonwald, Alabama, 6026]      map[id:1b7bf182-2482-4b8b-8210-9dc9ee51069e avatar:http://placehold.it/32x32 name:Anne Dalton email:[email protected] phone:+1 (994) 583-2947 address:660 Macdougal Street, Ticonderoga, Alaska, 7942]      map[id:f8027852-f52e-4bbb-bc9d-fb5e34929b40 avatar:http://placehold.it/32x32 name:Amie Ray email:[email protected] phone:+1 (853) 508-3649 address:878 Kane Street, Derwood, Minnesota, 3826]      map[id:b9842ab7-5053-48b4-a991-f5c63af8fb7e avatar:http://placehold.it/32x32 name:Hope Benton email:[email protected] phone:+1 (938) 542-2232 address:396 Osborn Street, Rowe, Massachusetts, 702]      map[id:8f9f6d8d-d14e-4ddc-acb2-eb96d3c3d7a8 avatar:http://placehold.it/32x32 name:Janine Kidd email:[email protected] phone:+1 (877) 474-2633 address:173 Manhattan Court, Hall, Virginia, 7376]      map[avatar:http://placehold.it/32x32 name:Kristen Yang email:[email protected] phone:+1 (862) 469-3446 address:203 Doughty Street, Westmoreland, Rhode Island, 849 id:210a6ae6-8227-4f26-a47c-448c400f26e9]      map[name:Murray Sosa email:[email protected] phone:+1 (814) 549-2536 address:811 Kingsland Avenue, Shepardsville, Hawaii, 9117 id:05f4f6af-19af-4b76-9aa8-9352281cf7d9 avatar:http://placehold.it/32x32]      map[phone:+1 (918) 476-2264 address:176 Underhill Avenue, Ebro, Washington, 8099 id:9d21268d-067c-4b16-a6cd-42d184c4c059 avatar:http://placehold.it/32x32 name:Paige Stanton email:[email protected]]      map[id:9946c19f-c226-4ff3-b578-57a249f8d0c7 avatar:http://placehold.it/32x32 name:Melisa Oconnor email:[email protected] phone:+1 (908) 429-3915 address:768 Wallabout Street, Cotopaxi, Florida, 3388]      map[id:ee0b82cb-4990-428b-ba36-088287a404ba avatar:http://placehold.it/32x32 name:Monique Poole email:[email protected] phone:+1 (925) 564-2690 address:232 Hubbard Place, Islandia, Michigan, 3722] ] 

Answer 1

The defaults that the json package will decode into when the type isn't declared are:

bool, for JSON booleans float64, for JSON numbers string, for JSON strings []interface{}, for JSON arrays map[string]interface{}, for JSON objects nil for JSON null 

Since each record is (in your example) a json object, you can assert each one as a map[string]interface{} like so:

for _, record := range view {     log.Printf(" [===>] Record: %s", record)      if rec, ok := record.(map[string]interface{}); ok {         for key, val := range rec {             log.Printf(" [========>] %s = %s", key, val)         }     } else {         fmt.Printf("record not a map[string]interface{}: %v\n", record)     } }