Parsing Nested JSON string - go

Question

I am trying to parse a nested json string
I did get it to work by using multiple structs, but I am wondering if I can parse the JSON without using an extra struct.
type Events struct {
Events []Event `json:"events"`
}
type Event struct {
Name string `json:"name"`
Url string `json:"url"`
Dates struct {
Start struct {
LocalDate string
LocalTime string
}
}
}
type Embed struct {
TM Events `json:"_embedded"`
}
func TMGetEventsByCategory(location string, category string) {
parameters := "city=" + location + "&classificationName=" + category + "&apikey=" + api_key
tmUrl := tmBaseUrl + parameters
resp, err := http.Get(tmUrl)
var embed Embed
var tm Event
if err != nil {
log.Printf("The HTTP request failed with error %s\n", err)
} else {
data, _ := ioutil.ReadAll(resp.Body)
err := json.Unmarshal(data, &embed)
json.Unmarshal(data, &tm)
}
}
JSON Data looks like this:
{
"_embedded": {
"events": [],
},
"OtherStuff": {
}
}
Is it possible to get rid of the Embed struct and read straight to the events part of the json string?

Answer 1

What you're looking for here is json.RawMessage. It can help delay parsing of certain values, and in you case map[string]json.RawMessage should represent the top-level object where you can selectively parse values. Here's a simplified example you can adjust to your case:
package main
import (
"encoding/json"
"fmt"
)
type Event struct {
Name string `json:"name"`
Url string `json:"url"`
}
func main() {
bb := []byte(`
{
"event": {"name": "joe", "url": "event://101"},
"otherstuff": 15.2,
"anotherstuff": 100
}`)
var m map[string]json.RawMessage
if err := json.Unmarshal(bb, &m); err != nil {
panic(err)
}
if eventRaw, ok := m["event"]; ok {
var event Event
if err := json.Unmarshal(eventRaw, &event); err != nil {
panic(err)
}
fmt.Println("Parsed Event:", event)
} else {
fmt.Println("Can't find 'event' key in JSON")
}
}
In your case look for the _embedded key and then Unmarshal its value to Events

Answer 2

yes of course
type Embed struct {
TM []struct {
Name string `json:"name"`
Url string `json:"url"`
Dates struct {
Start struct {
LocalDate string
LocalTime string
}
} // add tag here if you want
} `json:"_embedded"`
}