JSON

Must be included via require.

---

json.encode

Returns a string of JSON or MessagePack.

Parameters

1. data — A boolean, number, string, or table to encode as JSON.
2. format — Can be "compact", "pretty", or "msgpack". Defaults to "compact".

pluto
local json = require("json")
local data
data = "Hello, world!"
print(json.encode(data, "pretty"))
--> "Hello, world!"
data = {
    key = "Hello, world!",
    nested = {
        nested_key = 1337
    }
}
print(json.encode(data, "pretty"))
--> {
-->     "key": "Hello, world!",
-->     "nested": {
-->         "nested_key": 1337
-->     }
--> }
print(json.encode({ 0, true, json.null }, "msgpack"):tohex()) --> 9300c3c0

Because Lua tables do not have order guarantees, you can add an __order field to fix the order:

pluto
local t = {
    __order = { "a", "b", "c" },
    a = 1,
    b = 2,
    c = 3
}
print(require"json".encode(t)) -- {"a":1,"b":2,"c":3}

The json.null value — assuming you did local json = require("json") — can be used to encode JSON null values.

pluto
local json = require("json")
print(json.encode(json.null)) --> null

---

json.decode

Returns multiple potential types. If you pass a serialized boolean, number, or string, then it will return the same type. If you pass a complex JSON object, it will return a table.

Parameters

1. data — The JSON or MessagePack data to decode.
2. flags — Options to augment the return value. Multiple options can be combined with bitwise OR (|). Defaults to 0.
   • json.withnull — decodes JSON null values as json.null instead of nil.
   • json.withorder — adds an __order field to tables of decoded JSON objects. json.encode respects this, so this is perfect for modifying data while preserving order.
   • json.msgpack — treats the input as MessagePack data instead of JSON.

pluto
local json = require("json")
local encoded, decoded
encoded = [[{"key":"Hello, world!","nested":{"nested_key":1337}}]]
decoded = json.decode(encoded)
print(decoded.key) --> Hello, world!
print(decoded.nested.nested_key) --> 1337
-- Null & Order
encoded = [[{"null":null,"string":"Hello"}]]
decoded = json.decode(encoded, json.withnull | json.withorder)
assert(decoded.__order[1] == "null")
assert(decoded.null == json.null)
assert(json.encode(decoded) == encoded)
-- MessagePack
encoded = "\x93\x00\xc3\xc0"
decoded = json.decode(encoded, json.msgpack | json.withnull | json.withorder)
assert(decoded[1] == 0)
assert(decoded[2] == true)
assert(decoded[3] == json.null)
assert(json.encode(decoded, "msgpack") == encoded)