Go Struct Flags

A lightweight and flexible library for binding command‑line arguments to Go structs. Go Struct Flags provides automatic discovery of struct tags, default handlers for common types, custom overrides, before/after hooks, and optional JSON backup.

Features

• Auto‑Discovery: Read struct fields tagged with flag:"name,type[,choices]" and bind accordingly.

• Default Handlers: Built‑in support for:

  • bool → strconv.ParseBool
  • int → strconv.ParseInt
  • duration → time.ParseDuration
  • enum → string validation against allowed choices
  • strings → split colon‑separated values into []string

• Custom Handlers: Override any binding with AddBool, AddInt, AddDuration, AddEnum, or AddStrings.

• Hooks: Register BeforeHook and AfterHook callbacks around each binding operation.

• Batch Binding: Apply multiple key→args pairs at once with RunAll.

• Optional Backup: Write a JSON snapshot of your struct on NewBinder(..., autobackup=true).

Getting Started

Installation

go get github.com/mirkobrombin/go-struct-flags

Basic Usage

package main

import (
  "fmt"
  "time"

  "github.com/mirkobrombin/go-struct-flags/v1/binder"
)

type Config struct {
  Verbose bool          `flag:"verbose,bool"`
  Timeout time.Duration `flag:"timeout,duration"`
  Mode    string        `flag:"mode,enum,dev|prod"`
  Tags    []string      `flag:"tags,strings"`
}

func main() {
  var cfg Config
  binder, err := binder.NewBinder(&cfg, "./_backups", true)
  if err != nil {
    panic(err)
  }

  // Bind individual flags
  binder.Run("verbose", []string{"true"})
  binder.Run("timeout", []string{"30s"})
  binder.Run("mode",    []string{"prod"})
  binder.Run("tags",    []string{"alpha:beta:gamma"})

  // Or in batch
  settings := map[string][]string{
    "verbose": {"true"},
    "timeout": {"45s"},
    "mode":    {"dev"},
    "tags":    {"x:y:z"},
  }
  binder.RunAll(settings)

  fmt.Printf("Loaded config: %+v\n", cfg)
}

Documentation

• Getting Started
• Struct Tags
• Default Handlers
• Custom Hooks

License

This project is licensed under the MIT License. See the LICENSE file for details.