(Go) How to use toml files? - go

Question

As title, I want to know how to use toml files from golang.
Before that, I show my toml examples. Is it right?
[datatitle]
enable = true
userids = [
"12345", "67890"
]
[datatitle.12345]
prop1 = 30
prop2 = 10
[datatitle.67890]
prop1 = 30
prop2 = 10
And then, I want to set these data as type of struct.
As a result I want to access child element as below.
datatitle["12345"].prop1
datatitle["67890"].prop2
Thanks in advance!

Answer 1

First get BurntSushi's toml parser:
go get github.com/BurntSushi/toml
BurntSushi parses toml and maps it to structs, which is what you want.
Then execute the following example and learn from it:
package main
import (
"github.com/BurntSushi/toml"
"log"
)
var tomlData = `title = "config"
[feature1]
enable = true
userids = [
"12345", "67890"
]
[feature2]
enable = false`
type feature1 struct {
Enable bool
Userids []string
}
type feature2 struct {
Enable bool
}
type tomlConfig struct {
Title string
F1 feature1 `toml:"feature1"`
F2 feature2 `toml:"feature2"`
}
func main() {
var conf tomlConfig
if _, err := toml.Decode(tomlData, &conf); err != nil {
log.Fatal(err)
}
log.Printf("title: %s", conf.Title)
log.Printf("Feature 1: %#v", conf.F1)
log.Printf("Feature 2: %#v", conf.F2)
}
Notice the tomlData and how it maps to the tomlConfig struct.
See more examples at https://github.com/BurntSushi/toml

Answer 2

A small update for the year 2019 - there is now newer alternative to BurntSushi/toml with a bit richer API to work with .toml files:
pelletier/go-toml (and documentation)
For example having config.toml file (or in memory):
[postgres]
user = "pelletier"
password = "mypassword"
apart from regular marshal and unmarshal of the entire thing into predefined structure (which you can see in the accepted answer) with pelletier/go-toml you can also query individual values like this:
config, err := toml.LoadFile("config.toml")
if err != nil {
fmt.Println("Error ", err.Error())
} else {
// retrieve data directly
directUser := config.Get("postgres.user").(string)
directPassword := config.Get("postgres.password").(string)
fmt.Println("User is", directUser, " and password is", directPassword)
// or using an intermediate object
configTree := config.Get("postgres").(*toml.Tree)
user := configTree.Get("user").(string)
password := configTree.Get("password").(string)
fmt.Println("User is", user, " and password is", password)
// show where elements are in the file
fmt.Printf("User position: %v\n", configTree.GetPosition("user"))
fmt.Printf("Password position: %v\n", configTree.GetPosition("password"))
// use a query to gather elements without walking the tree
q, _ := query.Compile("$..[user,password]")
results := q.Execute(config)
for ii, item := range results.Values() {
fmt.Println("Query result %d: %v", ii, item)
}
}
UPDATE
There is also spf13/viper that works with .toml config files (among other supported formats), but it might be a bit overkill in many cases.
UPDATE 2
Viper is not really an alternative (credits to #GoForth).

Answer 3

This issue was solved using recommended pkg BurntSushi/toml!!
I did as below and it's part of code.
[toml example]
[title]
enable = true
[title.clientinfo.12345]
distance = 30
some_id = 6
[Golang example]
type TitleClientInfo struct {
Distance int `toml:"distance"`
SomeId int `toml:"some_id"`
}
type Config struct {
Enable bool `toml:"enable"`
ClientInfo map[string]TitleClientInfo `toml:"clientinfo"`
}
var config Config
_, err := toml.Decode(string(d), &config)
And then, it can be used as I expected.
config.ClientInfo[12345].Distance
Thanks!

Answer 4

With solution Viper you can use a configuration file in JSON, TOML, YAML, HCL, INI and others properties formats.
Create file:
./config.toml
First import:
import (config "github.com/spf13/viper")
Initialize:
config.SetConfigName("config")
config.AddConfigPath(".")
err := config.ReadInConfig()
if err != nil {
log.Println("ERROR", err.Error())
}
And get the value:
config.GetString("datatitle.12345.prop1")
config.Get("datatitle.12345.prop1").(int32)
Doc.: https://github.com/spf13/viper
e.g.: https://repl.it/#DarlanD/Viper-Examples#main.go

Answer 5

I am using this [1] go-toml library.
It works great for my uses. I wrote this [2] go util to deal with containerd config.toml file using go-toml
[1]https://github.com/pelletier/go-toml
[2]https://github.com/prakashmirji/toml-configer

Answer 6

I am using spf13/viper
3rd packages
Status
Project
Starts
Forks
Alive
spf13/viper
Alive
BurntSushi/toml
usage of viper
I tried to use a table to put the code and the contents of the configuration file together, but obviously, the editing did not match the final result, so I put the image up in the hope that it would make it easier for you to compare
package main
import (
"github.com/spf13/viper"
"log"
"os"
)
func main() {
check := func(err error) {
if err != nil {
panic(err)
}
}
myConfigPath := "test_config.toml"
fh, err := os.OpenFile(myConfigPath, os.O_RDWR, 0666)
check(err)
viper.SetConfigType("toml") // do not ignore
err = viper.ReadConfig(fh)
check(err)
// Read
log.Printf("%#v", viper.GetString("title")) // "my config"
log.Printf("%#v", viper.GetString("DataTitle.12345.prop1")) // "30"
log.Printf("%#v", viper.GetString("dataTitle.12345.prop1")) // "30" // case-insensitive
log.Printf("%#v", viper.GetInt("DataTitle.12345.prop1")) // 30
log.Printf("%#v", viper.GetIntSlice("feature1.userids")) // []int{456, 789}
// Write
viper.Set("database", "newuser")
viper.Set("owner.name", "Carson")
viper.Set("feature1.userids", []int{111, 222}) // overwrite
err = viper.WriteConfigAs(myConfigPath)
check(err)
}
title = "my config"
[datatitle]
[datatitle.12345]
prop1 = 30
[feature1]
userids = [456,789]
database = "newuser" # New
title = "my config"
[datatitle]
[datatitle.12345]
prop1 = 30
[feature1]
userids = [111,222] # Update
[owner] # New
name = "Carson"