Example of using gojay JSON decoder on Recursive structure

hierarchy_test.go

//
// An example of using gojay to decode a 'recursive' data-structure
// typical of hierarchal data used in a cli.
//
// Keywords: Decode JSON recursive
//
package main

import (
	"testing"

	"github.com/francoispqt/gojay"
)

type ItemArrayT []Item

type Item struct {
	name  string
	help  string
	child ItemArrayT
}

//
// Interface for the array of Items, used to decode the array
//
func (item *ItemArrayT) UnmarshalJSONArray(dec *gojay.Decoder) error {
	it := Item{}

	if err := dec.Object(&it); err != nil {
		return err
	}

	*item = append(*item, it)
	return nil
}

//
// Interface for the decoding of the main object
//
func (item *Item) UnmarshalJSONObject(dec *gojay.Decoder, key string) error {
	switch key {
	case "name":
		return dec.String(&(item.name))
	case "help":
		return dec.String(&(item.help))
	case "child":
		return dec.AddArray(&(item.child))
	}

	return nil
}

//
// Gotta tell gojay how many keys Item has
//
func (item *Item) NKeys() int {
	return 3
}

//
// Helper function for testing. Errors reported here are not reported
// here, instead the go-test framework will report it at the
// caller site.  Cool how this works.  Note also how we use
// interface{} types to do generic equality testing, so you can pass
// in two strings, two floats, two integers
//
func test_eq(t *testing.T, s1, s2 interface{}) {
	t.Helper()

	if s1 != s2 {
		t.Errorf("'%v' is not equaled to '%v'", s1, s2)
	}
}

//
// Main test routine
//
func TestRecursive(t *testing.T) {
	str := []byte(`
{
  "name": "top",
  "help": "Help for top level",
  "child" : [ {
        "name": "interfaces",
        "help": "Show interface help file",
	"child" : [{
		"name": "unit",
		"help": "Help for unit",
         }, {
                "name": "other",
		"help": "Help for other"
         }]
     }]
}`)

	top := &Item{}

	err := gojay.UnmarshalJSONObject(str, top)
	if err != nil {
		t.Fatal(err)
	}

	test_eq(t, top.name, "top")
	test_eq(t, len(top.child), 1)
	test_eq(t, top.child[0].name, "interfaces")
	test_eq(t, len(top.child[0].child), 2)
	test_eq(t, top.child[0].child[0].name, "unit")
	test_eq(t, top.child[0].child[0].help, "Help for unit")
	test_eq(t, top.child[0].child[1].name, "other")
	test_eq(t, top.child[0].child[1].help, "Help for other")
}