README
¶
TOML parser and encoder library for Golang 
TOML parser and encoder 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]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
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
-128to127) - int16 (from
-32768to32767) - int32 (from
-2147483648to2147483647) - int64 (from
-9223372036854775808to9223372036854775807) - int (same as
int32on 32bit environment, orint64on 64bit environment) - uint8 (from
0to255) - uint16 (from
0to65535) - uint32 (from
0to4294967295) - uint64 (from
0to18446744073709551615) - uint (same as
uinton 32bit environment, oruint64on 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 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.
duration = "10s"
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.
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.
API documentation
See Godoc.
License
MIT
Documentation
¶
Overview ¶
Package toml encodes and decodes the TOML configuration format using reflection.
This library is compatible with TOML version v0.4.0.
Example (TextUnmarshaler) ¶
Output: Unmarshaled: {Servers:[192.0.2.10 198.51.100.3]} Marshaled: servers = ["192.0.2.10", "198.51.100.3"]
Example (TextUnmarshalerError) ¶
Output: Unmarshal error: line 2: (toml_test.Config.Servers) invalid IP address: 198.51.100.500
Index ¶
- Variables
- func Marshal(v interface{}) ([]byte, error)
- func Parse(data []byte) (*ast.Table, error)
- func Unmarshal(data []byte, v interface{}) error
- func UnmarshalTable(t *ast.Table, v interface{}) error
- type Config
- type Decoder
- type Encoder
- type LineError
- type Marshaler
- type MarshalerRec
- type Unmarshaler
- type UnmarshalerRec
Examples ¶
Constants ¶
Variables ¶
var DefaultConfig = Config{
NormFieldName: defaultNormFieldName,
FieldToKey: snakeCase,
}
DefaultConfig contains the default options for encoding and decoding. Snake case (i.e. 'foo_bar') is used for key names.
Functions ¶
func Marshal ¶
Marshal returns the TOML encoding of v. It is shorthand for DefaultConfig.Marshal(v).
func Unmarshal ¶
Unmarshal parses the TOML data and stores the result in the value pointed to by v. It is shorthand for DefaultConfig.Unmarshal(data, v).
func UnmarshalTable ¶
UnmarshalTable applies the contents of an ast.Table to the value pointed at by v. It is shorthand for DefaultConfig.UnmarshalTable(t, v).
Types ¶
type Config ¶
type Config struct {
// NormFieldName is used to match TOML keys to struct fields. The function runs for
// both input keys and struct field names and should return a string that makes the
// two match. You must set this field to use the decoder.
//
// Example: The function in the default config removes _ and lowercases all keys. This
// allows a key called 'api_key' to match the struct field 'APIKey' because both are
// normalized to 'apikey'.
//
// Note that NormFieldName is not used for fields which define a TOML
// key through the struct tag.
NormFieldName func(typ reflect.Type, keyOrField string) string
// FieldToKey determines the TOML key of a struct field when encoding.
// You must set this field to use the encoder.
//
// Note that FieldToKey is not used for fields which define a TOML
// key through the struct tag.
FieldToKey func(typ reflect.Type, field string) string
// MissingField, if non-nil, is called when the decoder encounters a key for which no
// matching struct field exists. The default behavior is to return an error.
MissingField func(typ reflect.Type, key string) error
}
Config contains options for encoding and decoding.
func (*Config) Marshal ¶
Marshal returns the TOML encoding of v.
Struct values encode as TOML. Each exported struct field becomes a field of the TOML structure unless
- the field's tag is "-", or - the field is empty and its tag specifies the "omitempty" option.
The "toml" key in the struct field's tag value is the key name, followed by an optional comma and options. Examples:
// Field is ignored by this package. Field int `toml:"-"` // Field appears in TOML as key "myName". Field int `toml:"myName"` // Field appears in TOML as key "myName" and the field is omitted from the // result of encoding if its value is empty. Field int `toml:"myName,omitempty"` // Field appears in TOML as key "field", but the field is skipped if // empty. Note the leading comma. Field int `toml:",omitempty"`
func (*Config) NewDecoder ¶
NewDecoder returns a new Decoder that reads from r. Note that it reads all from r before parsing it.
func (*Config) NewEncoder ¶
NewEncoder returns a new Encoder that writes to w.
func (*Config) Unmarshal ¶
Unmarshal parses the TOML data and stores the result in the value pointed to by v.
Unmarshal will mapped to v that according to following rules:
TOML strings to string TOML integers to any int type TOML floats to float32 or float64 TOML booleans to bool TOML datetimes to time.Time TOML arrays to any type of slice TOML tables to struct or map TOML array tables to slice of struct or map
func (*Config) UnmarshalTable ¶
UnmarshalTable applies the contents of an ast.Table to the value pointed at by v.
UnmarshalTable will mapped to v that according to following rules:
TOML strings to string TOML integers to any int type TOML floats to float32 or float64 TOML booleans to bool TOML datetimes to time.Time TOML arrays to any type of slice TOML tables to struct or map TOML array tables to slice of struct or map
type Decoder ¶
type Decoder struct {
// contains filtered or unexported fields
}
A Decoder reads and decodes TOML from an input stream.
func NewDecoder ¶
NewDecoder returns a new Decoder that reads from r. It is shorthand for DefaultConfig.NewDecoder(r).
type Encoder ¶
type Encoder struct {
// contains filtered or unexported fields
}
A Encoder writes TOML to an output stream.
func NewEncoder ¶
NewEncoder returns a new Encoder that writes to w. It is shorthand for DefaultConfig.NewEncoder(w).
type LineError ¶
LineError is returned by Unmarshal, UnmarshalTable and Parse if the error is local to a line.
type Marshaler ¶
Marshaler can be implemented to override the encoding of TOML values. The returned text must be a simple TOML value (i.e. not a table) and is inserted into marshaler output.
This interface exists for backwards-compatibility reasons. You probably want to implement encoding.TextMarshaler or MarshalerRec instead.
type MarshalerRec ¶
type MarshalerRec interface {
MarshalTOML() (interface{}, error)
}
MarshalerRec can be implemented to override the TOML encoding of a type. The returned value is marshaled in place of the receiver.
type Unmarshaler ¶
Unmarshaler can be used to capture and process raw TOML source of a table or value. UnmarshalTOML must copy the input if it wishes to retain it after returning.
Note: this interface is retained for backwards compatibility. You probably want to implement encoding.TextUnmarshaler or UnmarshalerRec instead.
Example ¶
Output: config.Foo = 1 config.Servers = [[servers]] addr = "198.51.100.3:80" # a comment [[servers]] addr = "192.0.2.10:8080" timeout = "30s"
type UnmarshalerRec ¶
UnmarshalerRec may be implemented by types to customize their behavior when being unmarshaled from TOML. You can use it to implement custom validation or to set unexported fields.
UnmarshalTOML receives a function that can be called to unmarshal the original TOML value into a field or variable. It is safe to call the function more than once if necessary.
Example ¶
Output: Unmarshaled: {Servers:[{Addr:198.51.100.3:80 Timeout:10s} {Addr:192.0.2.10:8080 Timeout:30s}]}
Source Files
Directories
Valid go.mod file
Redistributable license