TOML parser library for Golang

TOML parser library for Golang.

This library is compatible with TOML version v0.4.0.

Installation

go get -u github.com/naoina/toml

Usage

The following TOML save as example.toml.

# This is a TOML document. Boom.

title = "TOML Example"

[owner]
name = "Lance Uppercut"
dob = 1979-05-27T07:32:00-08:00 # First class dates? Why not?

[database]
server = "192.168.1.1"
ports = [ 8001, 8001, 8002 ]
connection_max = 5000
enabled = true

[servers]

  # You can indent as you please. Tabs or spaces. TOML don't care.
  [servers.alpha]
  ip = "10.0.0.1"
  dc = "eqdc10"

  [servers.beta]
  ip = "10.0.0.2"
  dc = "eqdc10"

[clients]
data = [ ["gamma", "delta"], [1, 2] ]

# Line breaks are OK when inside arrays
hosts = [
  "alpha",
  "omega"
]

Then above TOML will mapping to tomlConfig struct using toml.Unmarshal.

package main

import (
    "io/ioutil"
    "os"
    "time"

    "github.com/naoina/toml"
)

type tomlConfig struct {
    Title string
    Owner struct {
        Name string
        Dob  time.Time
    }
    Database struct {
        Server        string
        Ports         []int
        ConnectionMax uint
        Enabled       bool
    }
    Servers map[string]Server
    Clients struct {
        Data  [][]interface{}
        Hosts []string
    }
}

type Server struct {
    IP string
    DC string
}

func main() {
    f, err := os.Open("example.toml")
    if err != nil {
        panic(err)
    }
    defer f.Close()
    buf, err := ioutil.ReadAll(f)
    if err != nil {
        panic(err)
    }
    var config tomlConfig
    if err := toml.Unmarshal(buf, &config); err != nil {
        panic(err)
    }
    // then to use the unmarshaled config...
}

Mappings

A key and value of TOML will map to the corresponding field. The fields of struct for mapping must be exported.

The rules of the mapping of key are following:

Exact matching

timeout_seconds = 256

type Config struct {
	Timeout_seconds int
}

Camelcase matching

server_name = "srv1"

type Config struct {
	ServerName string
}

Uppercase matching

ip = "10.0.0.1"

type Config struct {
	IP string
}

See the following examples for the value mappings.

String

val = "string"

type Config struct {
	Val string
}

Integer

val = 100

type Config struct {
	Val int
}

All types that can be used are following:

• int8 (from -128 to 127)
• int16 (from -32768 to 32767)
• int32 (from -2147483648 to 2147483647)
• int64 (from -9223372036854775808 to 9223372036854775807)
• int (same as int32 on 32bit environment, or int64 on 64bit environment)
• uint8 (from 0 to 255)
• uint16 (from 0 to 65535)
• uint32 (from 0 to 4294967295)
• uint64 (from 0 to 18446744073709551615)
• uint (same as uint on 32bit environment, or uint64 on 64bit environment)

Float

val = 3.1415

type Config struct {
	Val float32
}

All types that can be used are following:

• float32
• float64

Boolean

val = true

type Config struct {
	Val bool
}

Datetime

val = 2014-09-28T21:27:39Z

type Config struct {
	Val time.Time
}

Array

val = ["a", "b", "c"]

type Config struct {
	Val []string
}

Also following examples all can be mapped:

val1 = [1, 2, 3]
val2 = [["a", "b"], ["c", "d"]]
val3 = [[1, 2, 3], ["a", "b", "c"]]
val4 = [[1, 2, 3], [["a", "b"], [true, false]]]

type Config struct {
	Val1 []int
	Val2 [][]string
	Val3 [][]interface{}
	Val4 [][]interface{}
}

Table

[server]
type = "app"

  [server.development]
  ip = "10.0.0.1"

  [server.production]
  ip = "10.0.0.2"

type Config struct {
	Server map[string]Server
}

type Server struct {
	IP string
}

You can also use the following struct instead of map of struct.

type Config struct {
	Server struct {
		Development Server
		Production Server
	}
}

type Server struct {
	IP string
}

Array of Tables

[[fruit]]
  name = "apple"

  [fruit.physical]
    color = "red"
    shape = "round"

  [[fruit.variety]]
    name = "red delicious"

  [[fruit.variety]]
    name = "granny smith"

[[fruit]]
  name = "banana"

  [[fruit.variety]]
    name = "plantain"

type Config struct {
	Fruit []struct {
		Name string
		Physical struct {
			Color string
			Shape string
		}
		Variety []struct {
			Name string
		}
	}
}

Using toml.UnmarshalTOML interface

duration = "10s"

import time

type Config struct {
	Duration Duration
}

type Duration struct {
	time.Duration
}

func (d *Duration) UnmarshalTOML(data []byte) error {
	d.Duration, err := time.ParseDuration(string(data))
	return err
}

API documentation

See Godoc.

License

MIT