Reading the data which is in a map[string]interface{} - json

Question

Source server return the data in a Json format of multiple object
interfaces, how can we parse such data ?
I am using a variable of JSON map[string]interface{} type to hold the result from server
The data return from Server.
"data": [
{
"group": "PAA_TEST",
"id": "2018-04-10T09:24:18.000000Z",
"name": "PAA_STATION",
"released": true,
"version": 33
},
{
"group": "PAA_TEST",
"id": "2018-03-19T10:50:21.000000Z",
"name": "PAA_STATION",
"released": false,
"version": 32
}
my fmt.print output outputdata["data"] //where output data is of JSON
map[string]interface{}
[
map[group:PAA_TEST id:2018-04-10T09:24:18.000000Z name:PAA_STATION
released:true version:33]
map[group:PAA_TEST id:2018-03-19T10:50:21.000000Z name:PAA_STATION
released:false version:32]
]
How can we iterate with multiple Map interfaces? For example, if I just want to process the information with released status as true. I am trying various method for indexing but no luck yet.

Answer 1

The best solution is to decode the JSON directly to a Go type that matches the structure of the data. This avoids the type assertions required to dig through a map[string]interface{}.
I'll assume that the common function looks something like this:
func request(path string, ... more arguments) (map[string]interface{}}, error) {
...
resp, err := client.Do(req)
if err != nil {
return nil, err
}
defer resp.Body.Close()
...
var result map[string]interface{}
err := json.NewDecoder(resp.Body).Decode(&result)
return result, err
}
Change the function to take a pointer to the result as an argument:
func request(pv interface{}, path string, ... more arguments) error {
...
resp, err := client.Do(req)
if err != nil {
return err
}
defer resp.Body.Close()
...
err := json.NewDecoder(resp.Body).Decode(pv)
return err
}
Call this modified function like this:
var result struct {
Data []struct{
Group, ID, Name string
Released bool
Version int
}
}
err := request(&result, "some/path", ... more arguments )
if err != nil {
// handle error
}
for _, d := range result.Data {
if !d.Released {
continue
}
fmt.Println(d.Group, d.ID, d.Name, d.Version)
... process d
}