How to encode a JSON result, that has null for some of the fields.

cjson_encode_data_with_null.v

module main

import json

pub type Node = C.cJSON

struct UseJson {
	x int
}

fn suppress_json_warning() {
	json.encode(UseJson{})
}

fn C.cJSON_CreateObject() &C.cJSON

fn C.cJSON_CreateArray() &C.cJSON

fn C.cJSON_CreateBool(bool) &C.cJSON

fn C.cJSON_CreateTrue() &C.cJSON

fn C.cJSON_CreateFalse() &C.cJSON

fn C.cJSON_CreateNull() &C.cJSON

fn C.cJSON_CreateNumber() &C.cJSON

fn C.cJSON_CreateString() &C.cJSON

fn C.cJSON_CreateRaw(&u8) &C.cJSON

fn C.cJSON_IsInvalid(voidptr) bool

fn C.cJSON_IsFalse(voidptr) bool

fn C.cJSON_IsTrue(voidptr) bool

fn C.cJSON_IsBool(voidptr) bool

fn C.cJSON_IsNull(voidptr) bool

fn C.cJSON_IsNumber(voidptr) bool

fn C.cJSON_IsString(voidptr) bool

fn C.cJSON_IsArray(voidptr) bool

fn C.cJSON_IsObject(voidptr) bool

fn C.cJSON_IsRaw(voidptr) bool

fn C.cJSON_AddItemToObject(voidptr, &u8, voidptr)

fn C.cJSON_AddItemToArray(voidptr, voidptr)

fn C.cJSON_Delete(voidptr)

fn C.cJSON_Print(voidptr) &u8

fn create_object() &C.cJSON {
	return C.cJSON_CreateObject()
}

fn create_array() &C.cJSON {
	return C.cJSON_CreateArray()
}

fn create_string(val string) &C.cJSON {
	return C.cJSON_CreateString(val.str)
}

fn create_number(val f64) &C.cJSON {
	return C.cJSON_CreateNumber(val)
}

fn create_bool(val bool) &C.cJSON {
	return C.cJSON_CreateBool(val)
}

fn create_true() &C.cJSON {
	return C.cJSON_CreateTrue()
}

fn create_false() &C.cJSON {
	return C.cJSON_CreateFalse()
}

fn create_null() &C.cJSON {
	return C.cJSON_CreateNull()
}

fn delete(b voidptr) {
	C.cJSON_Delete(b)
}

fn add_item_to_object(obj &C.cJSON, key string, item &C.cJSON) {
	C.cJSON_AddItemToObject(obj, key.str, item)
}

fn add_item_to_array(obj &C.cJSON, item &C.cJSON) {
	C.cJSON_AddItemToArray(obj, item)
}

fn json_print(json &C.cJSON) string {
	mut s := C.cJSON_PrintUnformatted(json)	
	return unsafe { tos3(s) }
}
	
fn main() {
	mut root := create_object()
	add_item_to_object(root, 'name', create_string('Andre'))
	add_item_to_object(root, 'age', create_null())
	s := json_print(root)
	dump(s)
}