goenumcodegen

go-enum-codegen

go-enum-codegen is a command-line tool that generates methods to satisfy json.Marshaler, json.Unmarshaler, sql.Scanner, & driver.Valuer interfaces for common enum patterns.

With the default settings and given a type MyEnum that is a string or integer type, go-enum-codegen will create a new self-contained Go source file implementing:

// myenum.gen.go
// Code generated by "go-enum-codegen -type MyEnum"; DO NOT EDIT

package mypackage

func (t MyEnum) MarshalJSON() ([]byte, error) {
	...
}

func (t *MyEnum) UnmarshalJSON(data []byte) error {
	...
}

func (t MyEnum) Value() (driver.Value, error) {
	...
}

func (t *MyEnum) Scan(v any) error  {
	...
}

Installation

go-enum-codegen can be installed using the recommended tools.go pattern] so it can be managed alongside the rest of your module.

To do so, create a file called tools/tools.go at the root of your module with the following contents:

//go:build tools
// +build tools

package main

import (
	_ "github.com/ejfrick/go-enum-codegen/cmd/go-enum-codegen"
)

Then, you can invoke go-enum-codegen like so:

//go:generate go run github.com/ejfrick/go-enum-codegen/cmd/go-enum-codegen -type MyEnum

go-enum-codegen can alternatively be installed as a binary:

$ go install github.com/ejfrick/go-enum-codegen/cmd/go-enum-codegen@latest
$ go-enum-codegen -version

When installed as a binary, it would be invoked as follows:

//go:generate go-enum-codegen -type MyEnum

Usage

Usage of go-enum-codegen:
  -e    
        same as -error-on-unknown
  -error-on-unknown
        whether to return an error if scanning or unmarshalling an unknown value; automatically set to true when iota is first set to "_" or there is no enum equal to the empty value of its underlying type; otherwise default is false and an unknown value will be assigned to the enum with the empty value of its underlying type
  -h    
        same as -help.
  -help
        show this help and exit
  -json
        generate only json.Marshaler and json.Unmarshaler methods; default false
  -output string
        output file name; default srcdir/<type>.gen.go
  -sql
        generate only sql.Scanner and driver.Value methods; default false
  -stringer
        use the String() method of the enum instead of the underlying integer value; default false
  -tags string
        comma-separated list of build tags to apply
  -type string
        comma-separated list of type names; must be set
  -version
        show version and exit

Examples

You can find examples for several different scenarios in [./examples]

To-Do

• [] Homebrew formula
• [] More tests
• [] More docs

Feature Requests, Bug Reports, Contributing, Etc.

Please open an issue (or a pull request!)