strict json parser in golang - json

Question

In Go, I have some JSON from third-party API and then I'm trying to parse it:
b := []byte(`{"age":21,"married":true}`)
var response_hash map[string]string
_ = json.Unmarshal(b, &response_hash)
But it fails (response_hash becomes empty) and Unmarshal can handle only JSON with quotes:
b := []byte(`{"age":"21","married":"true"}`)
var response_hash map[string]string
_ = json.Unmarshal(b, &response_hash)
Is there any way to read the first version of JSON from third-party API?

Answer 1

Go is a strongly typed language. You need to specify what types the JSON encoder is to expect. You're creating a map of string values but your two json values are an integer and a boolean value.
Here's a working example with a struct.
http://play.golang.org/p/oI1JD1UUhu
package main
import (
"fmt"
"encoding/json"
)
type user struct {
Age int
Married bool
}
func main() {
src_json := []byte(`{"age":21,"married":true}`)
u := user{}
err := json.Unmarshal(src_json, &u)
if err != nil {
panic(err)
}
fmt.Printf("Age: %d\n", u.Age)
fmt.Printf("Married: %v\n", u.Married)
}
If you want to do it in a more dynamic manner you can use a map of interface{} values. You just have to do type assertions when you use the values.
http://play.golang.org/p/zmT3sPimZC
package main
import (
"fmt"
"encoding/json"
)
func main() {
src_json := []byte(`{"age":21,"married":true}`)
// Map of interfaces can receive any value types
u := map[string]interface{}{}
err := json.Unmarshal(src_json, &u)
if err != nil {
panic(err)
}
// Type assert values
// Unmarshal stores "age" as a float even though it's an int.
fmt.Printf("Age: %1.0f\n", u["age"].(float64))
fmt.Printf("Married: %v\n", u["married"].(bool))
}