Go to JSON type mappings

Mapping between Go types and JSON types:

JSON type	Go type
null	nil
boolean	bool
number	float64 or int
string	string
array	slice
dictionary	map[struct]interface{} or struct

Here’s how they look in practice:

main.go

func printSerialized(v interface{}, w io.Writer) {
	d, err := json.Marshal(v)
	if err != nil {
		log.Fatalf("json.Marshal failed with '%s'\n", err)
	}
	fmt.Fprintf(w, "%T\t%s\n", v, string(d))
}

	w := new(tabwriter.Writer)
	w.Init(os.Stdout, 5, 0, 1, ' ', 0)
	fmt.Fprint(w, "Go type:\tJSON value:\n")
	fmt.Fprint(w, "\t\n")
	printSerialized(nil, w)
	printSerialized(5, w)
	printSerialized(8.23, w)
	printSerialized("john", w)
	ai := []int{5, 4, 18}
	printSerialized(ai, w)
	a := []interface{}{4, "string"}
	printSerialized(a, w)
	d := map[string]interface{}{
		"i": 5,
		"s": "foo",
	}
	printSerialized(d, w)
	s := struct {
		Name string
		Age  int
	}{
		Name: "John",
		Age:  37,
	}
	printSerialized(s, w)
	w.Flush()

Output:

Go type:                        JSON value:
                                
<nil>                           null
int                             5
float64                         8.23
string                          "john"
[]int                           [5,4,18]
[]interface {}                  [4,"string"]
map[string]interface {}         {"i":5,"s":"foo"}
struct { Name string; Age int } {"Name":"John","Age":37}

Found a mistake? Have a question or improvement idea? Let me know.

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