luajson

Documentation

Overview

Package luajson converts between glua values and JSON, straight from tables to JSON text and back without an intermediate tree, and gives scripts a json module.

A table that is a non-empty sequence, keys 1 to n and no others, becomes a JSON array. Any other table becomes an object, with its keys in sorted order so that the output is deterministic; integer keys become their decimal strings. Strings must be valid UTF-8. Functions, userdata, coroutines, NaN and infinities cannot be encoded, and a float -0 is written as 0. Tables nested more than 64 deep, and tables that contain themselves, are errors.

Decoding gives tables, strings, booleans and numbers: an integer for a number written without a fraction or exponent that fits in 64 bits, a float otherwise. A JSON null is nil, so a null in an array leaves a hole and a null member is absent.

Example

package main

import (
	"context"
	"fmt"

	lua "github.com/folbricht/glua"
	"github.com/folbricht/glua/luajson"
)

func main() {
	rt := lua.MustNew(luajson.Module("json"))
	script, err := rt.Load(context.Background(), "hook.lua", `
		function handle(body)
			local req = json.decode(body)
			return json.encode({user = req.user, items = #req.items, ok = true})
		end`)
	if err != nil {
		panic(err)
	}
	handle, _ := script.Func1[string, string]("handle")
	out, err := handle(context.Background(), `{"user": "ann", "items": [1, 2, 3]}`)
	fmt.Println(out, err)

	v, _ := luajson.Unmarshal([]byte(`{"port": 8080}`))
	b, _ := luajson.Marshal(v)
	fmt.Println(string(b))
}

Output:
{"items":3,"ok":true,"user":"ann"} <nil>
{"port":8080}

Index

• func Marshal(v lua.Value, opts ...Options) ([]byte, error)
• func MarshalWrite(w io.Writer, v lua.Value, opts ...Options) error
• func Module(name string) lua.Option
• func Unmarshal(data []byte) (lua.Value, error)
• func UnmarshalRead(r io.Reader) (lua.Value, error)
• type Options

Examples

• Package

Functions

func Marshal

func Marshal(v lua.Value, opts ...Options) ([]byte, error)

Marshal encodes v as JSON.

func MarshalWrite

func MarshalWrite(w io.Writer, v lua.Value, opts ...Options) error

MarshalWrite encodes v as JSON to w.

func Module

func Module(name string) lua.Option

Module returns an option that defines a module of the given name, usually "json", with encode(value [, indent]) and decode(text). What decode makes, and the text encode makes, count toward the calling script's budgets.

rt := lua.MustNew(luajson.Module("json"))
-- in Lua: local doc = json.decode(text); local text = json.encode({ok = true})

func Unmarshal

func Unmarshal(data []byte) (lua.Value, error)

Unmarshal decodes one JSON value into tables, strings, numbers and booleans.

func UnmarshalRead

func UnmarshalRead(r io.Reader) (lua.Value, error)

UnmarshalRead decodes one JSON value from r.

Types

type Options

type Options struct {
	Indent string // when set, one member or element per line, indented by this: spaces and tabs only
}

Options for Marshal.