## TOML parser and encoder for Go with reflection
TOML stands for Tom's Obvious, Minimal Language. This Go package provides a
reflection interface similar to Go's standard library `json` and `xml`
packages. This package also supports the `encoding.TextUnmarshaler` and
`encoding.TextMarshaler` interfaces so that you can define custom data
representations. (There is an example of this below.)
Compatible with TOML version [v1.0.0](https://toml.io/en/v1.0.0).
Documentation: https://godocs.io/github.com/BurntSushi/toml
See the [releases page](https://github.com/BurntSushi/toml/releases) for a
changelog; this information is also in the git tag annotations (e.g. `git show
v0.4.0`).
This library requires Go 1.13 or newer; install it with:
$ go get github.com/BurntSushi/toml
It also comes with a TOML validator CLI tool:
$ go get github.com/BurntSushi/toml/cmd/tomlv
$ tomlv some-toml-file.toml
### Testing
This package passes all tests in
[toml-test](https://github.com/BurntSushi/toml-test) for both the decoder
and the encoder.
### Examples
This package works similarly to how the Go standard library handles XML and
JSON. Namely, data is loaded into Go values via reflection.
For the simplest example, consider some TOML file as just a list of keys
and values:
```toml
Age = 25
Cats = [ "Cauchy", "Plato" ]
Pi = 3.14
Perfection = [ 6, 28, 496, 8128 ]
DOB = 1987-07-05T05:45:00Z
```
Which could be defined in Go as:
```go
type Config struct {
Age int
Cats []string
Pi float64
Perfection []int
DOB time.Time // requires `import time`
}
```
And then decoded with:
```go
var conf Config
if _, err := toml.Decode(tomlData, &conf); err != nil {
// handle error
}
```
You can also use struct tags if your struct field name doesn't map to a TOML
key value directly:
```toml
some_key_NAME = "wat"
```
```go
type TOML struct {
ObscureKey string `toml:"some_key_NAME"`
}
```
Beware that like other most other decoders **only exported fields** are
considered when encoding and decoding; private fields are silently ignored.
### Using the `encoding.TextUnmarshaler` interface
Here's an example that automatically parses duration strings into
`time.Duration` values:
```toml
[[song]]
name = "Thunder Road"
duration = "4m49s"
[[song]]
name = "Stairway to Heaven"
duration = "8m03s"
```
Which can be decoded with:
```go
type song struct {
Name string
Duration duration
}
type songs struct {
Song []song
}
var favorites songs
if _, err := toml.Decode(blob, &favorites); err != nil {
log.Fatal(err)
}
for _, s := range favorites.Song {
fmt.Printf("%s (%s)\n", s.Name, s.Duration)
}
```
And you'll also need a `duration` type that satisfies the
`encoding.TextUnmarshaler` interface:
```go
type duration struct {
time.Duration
}
func (d *duration) UnmarshalText(text []byte) error {
var err error
d.Duration, err = time.ParseDuration(string(text))
return err
}
```
To target TOML specifically you can implement `UnmarshalTOML` TOML interface in
a similar way.
### More complex usage
Here's an example of how to load the example from the official spec page:
```toml
# This is a TOML document. Boom.
title = "TOML Example"
[owner]
name = "Tom Preston-Werner"
organization = "GitHub"
bio = "GitHub Cofounder & CEO\nLikes tater tots and beer."
dob = 1979-05-27T07:32:00Z # 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] ] # just an update to make sure parsers support it
# Line breaks are OK when inside arrays
hosts = [
"alpha",
"omega"
]
```
And the corresponding Go types are:
```go
type tomlConfig struct {
Title string
Owner ownerInfo
DB database `toml:"database"`
Servers map[string]server
Clients clients
}
type ownerInfo struct {
Name string
Org string `toml:"organization"`
Bio string
DOB time.Time
}
type database struct {
Server string
Ports []int
ConnMax int `toml:"connection_max"`
Enabled bool
}
type server struct {
IP string
DC string
}
type clients struct {
Data [][]interface{}
Hosts []string
}
```
Note that a case insensitive match will be tried if an exact match can't be
found.
A working example of the above can be found in `_examples/example.{go,toml}`.
