Unmarshaling nested JSON objects
Yes. With gjson all you have to do now is:
bar := gjson.Get(json, "foo.bar")
bar
could be a struct property if you like. Also, no maps.
This is an example of how to unmarshall JSON responses from the Safebrowsing v4 API sbserver proxy server: https://play.golang.org/p/4rGB5da0Lt
// this example shows how to unmarshall JSON requests from the Safebrowsing v4 sbserver
package main
import (
"fmt"
"log"
"encoding/json"
)
// response from sbserver POST request
type Results struct {
Matches []Match
}
// nested within sbserver response
type Match struct {
ThreatType string
PlatformType string
ThreatEntryType string
Threat struct {
URL string
}
}
func main() {
fmt.Println("Hello, playground")
// sample POST request
// curl -X POST -H 'Content-Type: application/json'
// -d '{"threatInfo": {"threatEntries": [{"url": "http://testsafebrowsing.appspot.com/apiv4/ANY_PLATFORM/MALWARE/URL/"}]}}'
// http://127.0.0.1:8080/v4/threatMatches:find
// sample JSON response
jsonResponse := `{"matches":[{"threatType":"MALWARE","platformType":"ANY_PLATFORM","threatEntryType":"URL","threat":{"url":"http://testsafebrowsing.appspot.com/apiv4/ANY_PLATFORM/MALWARE/URL/"}}]}`
res := &Results{}
err := json.Unmarshal([]byte(jsonResponse), res)
if(err!=nil) {
log.Fatal(err)
}
fmt.Printf("%v\n",res)
fmt.Printf("\tThreat Type: %s\n",res.Matches[0].ThreatType)
fmt.Printf("\tPlatform Type: %s\n",res.Matches[0].PlatformType)
fmt.Printf("\tThreat Entry Type: %s\n",res.Matches[0].ThreatEntryType)
fmt.Printf("\tURL: %s\n",res.Matches[0].Threat.URL)
}
Is there a way to unmarshal the nested bar property and assign it directly to a struct property without creating a nested struct?
No, encoding/json cannot do the trick with ">some>deep>childnode" like encoding/xml can do. Nested structs is the way to go.
Like what Volker mentioned, nested structs is the way to go. But if you really do not want nested structs, you can override the UnmarshalJSON func.
https://play.golang.org/p/dqn5UdqFfJt
type A struct {
FooBar string // takes foo.bar
FooBaz string // takes foo.baz
More string
}
func (a *A) UnmarshalJSON(b []byte) error {
var f interface{}
json.Unmarshal(b, &f)
m := f.(map[string]interface{})
foomap := m["foo"]
v := foomap.(map[string]interface{})
a.FooBar = v["bar"].(string)
a.FooBaz = v["baz"].(string)
a.More = m["more"].(string)
return nil
}
Please ignore the fact that I'm not returning a proper error. I left that out for simplicity.
UPDATE: Correctly retrieving "more" value.