cfg

Documentation

Index

• type EnvOption
  • func EnvSplitter(splitter string) EnvOption
• type FileDecoder
• type FileOption
  • func FileDecoders(decoder ...FileDecoder) FileOption
  • func FileFlagSet(set FlagSet) FileOption
• type FlagOption
  • func FlagSplitter(splitter string) FlagOption
  • func FlagWithFlagSet(set FlagSet) FlagOption
• type FlagSet
• type JSON
  • func (JSON) Decode(r io.Reader, a any) error
  • func (JSON) ExtNames() []string
  • func (JSON) MimeNames() []string
  • func (JSON) TagName() string
• type Parser
  • func Parse[T any](src ...Source) *Parser[T]
  • func (p *Parser[T]) Parse(ctx context.Context, v *T) error
• type Source
  • func FromEnv(prefix string, opt ...EnvOption) Source
  • func FromFile(flagName, flagValue, flagUsage string, opt ...FileOption) Source
  • func FromFlag(prefix string, opt ...FlagOption) Source

Examples

• Parser

Types

type EnvOption

type EnvOption func(*envSource)

func EnvSplitter

func EnvSplitter(splitter string) EnvOption

type FileDecoder

type FileDecoder interface {
	ExtNames() []string
	MimeNames() []string
	TagName() string
	Decode(r io.Reader, a any) error
}

type FileOption

type FileOption func(s *fileSource)

func FileDecoders

func FileDecoders(decoder ...FileDecoder) FileOption

func FileFlagSet

func FileFlagSet(set FlagSet) FileOption

type FlagOption

type FlagOption func(*flagSource)

func FlagSplitter

func FlagSplitter(splitter string) FlagOption

func FlagWithFlagSet

func FlagWithFlagSet(set FlagSet) FlagOption

type FlagSet

type FlagSet interface {
	BoolVar(p *bool, name string, value bool, usage string)
	StringVar(p *string, name string, value string, usage string)
	DurationVar(p *time.Duration, name string, value time.Duration, usage string)
	TextVar(p encoding.TextUnmarshaler, name string, value encoding.TextMarshaler, usage string)
	Float64Var(p *float64, name string, value float64, usage string)
	Uint64Var(p *uint64, name string, value uint64, usage string)
	UintVar(p *uint, name string, value uint, usage string)
	Int64Var(p *int64, name string, value int64, usage string)
	IntVar(p *int, name string, value int, usage string)
	Var(value flag.Value, name string, usage string)
}

type JSON

type JSON struct{}

func (JSON) Decode

func (JSON) Decode(r io.Reader, a any) error

func (JSON) ExtNames

func (JSON) ExtNames() []string

func (JSON) MimeNames

func (JSON) MimeNames() []string

func (JSON) TagName

func (JSON) TagName() string

type Parser

type Parser[T any] struct {
	// contains filtered or unexported fields
}

Example

An example to load `Config` from sources orderly: - from a config file - from env variables - from flags

The same field in the flag overwrites the env variable, and the same file in the env variable overwrites the value in the config file.

package main

import (
	"bytes"
	"context"
	"flag"
	"fmt"
	"os"
	"strings"

	"github.com/googollee/go-cfg"
)

type Config struct {
	Str     string `cfg:"str,,string value from file"`
	I       int    `cfg:"int,,int value from file"`
	FromEnv struct {
		Str string `cfg:"str,none,string value from env"`
	} `cfg:"from_env"`
	FromFlag struct {
		Str string `cfg:"str,none,string value from flags"`
	} `cfg:"from_flag"`
	WithDefault struct {
		Str string `cfg:"str,default_value,string value with default"`
	} `cfg:"with_default"`
}

// An example to load `Config` from sources orderly:
// - from a config file
// - from env variables
// - from flags
//
// The same field in the flag overwrites the env variable, and the same file in the env variable overwrites the value in the config file.
func main() {
	os.Setenv("DEMO_FROM_ENV_STR", "string_from_env")

	set := flag.NewFlagSet("demo", flag.PanicOnError)

	parser := cfg.Parse[Config](
		cfg.FromFile("config", "./testdata/config.json", "config file",
			cfg.FileDecoders(cfg.JSON{}),
			cfg.FileFlagSet(set)),
		cfg.FromEnv("DEMO", cfg.EnvSplitter("_")),
		cfg.FromFlag("demo", cfg.FlagSplitter("."), cfg.FlagWithFlagSet(set)),
	)

	if err := set.Parse([]string{
		"--config", "./testdata/config.json",
		"--demo.from_flag.str", "string_from_flag",
	}); err != nil {
		fmt.Println("flag error:", err)
		return
	}

	var buf bytes.Buffer
	set.SetOutput(&buf)
	set.Usage()
	fmt.Println(strings.ReplaceAll(buf.String(), "\t", "  "))

	var config Config
	if err := parser.Parse(context.Background(), &config); err != nil {
		fmt.Println("load config error:", err)
		return
	}

	fmt.Println("config:", config)

}

Output:

Usage of demo:
  -config string
      config file (default "./testdata/config.json")
  -demo.from_env.str value
      string value from env (default none)
  -demo.from_flag.str value
      string value from flags (default none)
  -demo.int value
      int value from file
  -demo.str value
      string value from file
  -demo.with_default.str value
      string value with default (default default_value)

config: {string 10 {string_from_env} {string_from_flag} {default_value}}

func Parse

func Parse[T any](src ...Source) *Parser[T]

func (*Parser[T]) Parse

func (p *Parser[T]) Parse(ctx context.Context, v *T) error

type Source

type Source interface {
	Setup(t reflect.Type) error
	Parse(ctx context.Context, v any) error
}

func FromEnv

func FromEnv(prefix string, opt ...EnvOption) Source

func FromFile

func FromFile(flagName, flagValue, flagUsage string, opt ...FileOption) Source

func FromFlag

func FromFlag(prefix string, opt ...FlagOption) Source