autobind

README

= README for Autobind
Author <jeroen@hierynomus.com>
:source-highlighter: pygments

[![GoDoc](https://godoc.org/github.com/hierynomus/autobind?status.svg)](https://godoc.org/github.com/hierynomus/autobind)

Autobind is a library that can use Golang struct annotations to automatically bind Viper and Cobra flags to struct fields.

It is inspired by the excellent work of @spf13 on Viper and Cobra.

Installation
------------

Installing Autobind is as simple as running:

[source,sh]
----
go get github.com/hierynomus/autobind
----

Usage
-----

[source,go]
----
    package main

    import (
        "github.com/hierynomus/autobind"
        "github.com/spf13/cobra"
        "github.com/spf13/viper"
    )

    type Config struct {
        Host string `cobra:"host" env:"HOST" viper:"host" default:"localhost"`
        Port int    `cobra:"port" env:"PORT" viper:"port" default:"8080"`
    }

    func main() {
        var config Config

        vp := viper.New()
        vp.SetConfigName("config")
        vp.AddConfigPath(".")
        vp.SetConfigType("yaml")
        if err := vp.ReadInConfig(); err != nil {
            if _, ok := err.(viper.ConfigFileNotFoundError); ok {
                logger.Warn().Msg("No config file found... Continuing with defaults")
                // Config file not found; ignore error if desired
            } else {
                fmt.Printf("%s", err)
                os.Exit(1)
            }
        }

        cmd := &cobra.Command{
            Run: func(cmd *cobra.Command, args []string) {
                // Do something with config
            },
        }

        binder := &autobind.Autobinder{
            ConfigObject: &config,
            Viper: vp,
            EnvPrefix: "MYAPP",
        }

        binder.Bind(context.Background(), cmd, []string{})

        cmd.Execute()
    }
----

Configuration
-------------

The following items can be set on the `Autobind` struct:

[options="header"]
|=====================
| Name | Description
| `ConfigObject` | The (pointer to the) struct that should be bound to the flags and environment variables.
| `Viper` | The instantiated Viper instace.
| `UseNesting` | Whether to use nested keys in Viper if encountering a sub-struct in the config object.
| `EnvPrefix` | The prefix to use for environment variables.
| `SetDefaults` | Whether to set the default values on config object.
| `Casters` | A map of custom cast functions to use for specific types.

Documentation

Index

• Constants
• func AutoBind(vp *viper.Viper, cfg interface{}) func(cmd *cobra.Command, args []string) error
• type Autobinder
  • func (b *Autobinder) Bind(ctx context.Context, cmd *cobra.Command, prefix []string)
  • func (b *Autobinder) Cast(key string, caster Caster)
• type Caster

Constants

const (
	ViperTag = "viper"
	CobraTag = "cobra"
	EnvTag   = "env"
)

Functions

func AutoBind

func AutoBind(vp *viper.Viper, cfg interface{}) func(cmd *cobra.Command, args []string) error

Types

type Autobinder

type Autobinder struct {
	ConfigObject interface{}
	Viper        *viper.Viper
	UseNesting   bool
	EnvPrefix    string            // Viper prefix for environment variables, viper does not expose this, and because we construct the ENV variables, the prefix isn't set by Viper.
	SetDefaults  bool              // Set default values for Viper keys that are not set
	Casters      map[string]Caster // Custom casters
}

func (*Autobinder) Bind

func (b *Autobinder) Bind(ctx context.Context, cmd *cobra.Command, prefix []string)

func (*Autobinder) Cast

func (b *Autobinder) Cast(key string, caster Caster)

type Caster

type Caster func(interface{}) interface{}