niltoempty

Recursively initializes all nil maps and slices in a given object, so json.Marshal() serializes they as empty object {} or array [] instead of null.

This is more complete solution based on the idea from nilslice. It works not only for nil slices but also for nil maps.

	type T struct {
		M  map[string]any  `json:"m"`
		S  []any           `json:"s"`
		PM *map[string]any `json:"pm"`
		PS *[]any          `json:"ps"`
	}

	var v T

	m1, _ := json.MarshalIndent(v, "", "    ")
	fmt.Println(string(m1))
	m2, _ := json.MarshalIndent(niltoempty.Initialize(&v), "", "    ")
	fmt.Println(string(m2))
	// output
	// {
	//     "m": null,
	//     "s": null,
	//     "pm": null,
	//     "ps": null
	// }
	// {
	//     "m": {},
	//     "s": [],
	//     "pm": null,
	//     "ps": null
	// }