# TOML parser and encoder library for Golang [](https://travis-ci.org/naoina/toml)
[TOML](https://github.com/toml-lang/toml) parser and encoder library for [Golang](http://golang.org/).
This library is compatible with TOML version [v0.4.0](https://github.com/toml-lang/toml/blob/master/versions/en/toml-v0.4.0.md).
## Installation
go get -u github.com/naoina/toml
## Usage
The following TOML save as `example.toml`.
```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`.
```go
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]ServerInfo
Clients struct {
Data [][]interface{}
Hosts []string
}
}
type ServerInfo struct {
IP net.IP
DC string
}
func main() {
f, err := os.Open("example.toml")
if err != nil {
panic(err)
}
defer f.Close()
var config Config
if err := toml.NewDecoder(f).Decode(&config); err != nil {
panic(err)
}
// then to use the unmarshaled config...
fmt.Println("IP of server 'alpha':", config.Servers["alpha"].IP)
}
```
## 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
```toml
timeout_seconds = 256
```
```go
type Config struct {
Timeout_seconds int
}
```
#### Camelcase matching
```toml
server_name = "srv1"
```
```go
type Config struct {
ServerName string
}
```
#### Uppercase matching
```toml
ip = "10.0.0.1"
```
```go
type Config struct {
IP string
}
```
See the following examples for the value mappings.
### String
```toml
val = "string"
```
```go
type Config struct {
Val string
}
```
### Integer
```toml
val = 100
```
```go
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
```toml
val = 3.1415
```
```go
type Config struct {
Val float32
}
```
All types that can be used are following:
* float32
* float64
### Boolean
```toml
val = true
```
```go
type Config struct {
Val bool
}
```
### Datetime
```toml
val = 2014-09-28T21:27:39Z
```
```go
type Config struct {
Val time.Time
}
```
### Array
```toml
val = ["a", "b", "c"]
```
```go
type Config struct {
Val []string
}
```
Also following examples all can be mapped:
```toml
val1 = [1, 2, 3]
val2 = [["a", "b"], ["c", "d"]]
val3 = [[1, 2, 3], ["a", "b", "c"]]
val4 = [[1, 2, 3], [["a", "b"], [true, false]]]
```
```go
type Config struct {
Val1 []int
Val2 [][]string
Val3 [][]interface{}
Val4 [][]interface{}
}
```
### Table
```toml
[server]
type = "app"
[server.development]
ip = "10.0.0.1"
[server.production]
ip = "10.0.0.2"
```
```go
type Config struct {
Server map[string]Server
}
type Server struct {
IP string
}
```
You can also use the following struct instead of map of struct.
```go
type Config struct {
Server struct {
Development Server
Production Server
}
}
type Server struct {
IP string
}
```
### Array of Tables
```toml
[[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"
```
```go
type Config struct {
Fruit []struct {
Name string
Physical struct {
Color string
Shape string
}
Variety []struct {
Name string
}
}
}
```
### Using the `encoding.TextUnmarshaler` interface
Package toml supports `encoding.TextUnmarshaler` (and `encoding.TextMarshaler`). You can
use it to apply custom marshaling rules for certain types. The `UnmarshalText` method is
called with the value text found in the TOML input. TOML strings are passed unquoted.
```toml
duration = "10s"
```
```go
import time
type Duration time.Duration
// UnmarshalText implements encoding.TextUnmarshaler
func (d *Duration) UnmarshalText(data []byte) error {
duration, err := time.ParseDuration(string(data))
if err == nil {
*d = Duration(duration)
}
return err
}
// MarshalText implements encoding.TextMarshaler
func (d Duration) MarshalText() ([]byte, error) {
return []byte(time.Duration(d).String()), nil
}
type ConfigWithDuration struct {
Duration Duration
}
```
### Using the `toml.UnmarshalerRec` interface
You can also override marshaling rules specifically for TOML using the `UnmarshalerRec`
and `MarshalerRec` interfaces. These are useful if you want to control how structs or
arrays are handled. You can apply additional validation or set unexported struct fields.
Note: `encoding.TextUnmarshaler` and `encoding.TextMarshaler` should be preferred for
simple (scalar) values because they're also compatible with other formats like JSON or
YAML.
[See the UnmarshalerRec example](https://godoc.org/github.com/naoina/toml/#example_UnmarshalerRec).
### Using the `toml.Unmarshaler` interface
If you want to deal with raw TOML syntax, use the `Unmarshaler` and `Marshaler`
interfaces. Their input and output is raw TOML syntax. As such, these interfaces are
useful if you want to handle TOML at the syntax level.
[See the Unmarshaler example](https://godoc.org/github.com/naoina/toml/#example_Unmarshaler).
## API documentation
See [Godoc](http://godoc.org/github.com/naoina/toml).
## License
MIT