gonumerate

README

Gonumerate

Gonumerate is an enumeration generator for Go.

Installation

go get github.com/nickmro/gonumerate

Usage

Usage:
 gonumerate [OPTION]...

Options:
 -type    The enum type name (Required)
 -values  The enum values
 -prefix  The prefix to apply to each enum value
 -json    The JSON encoding type {string, int}
 -sql     The SQL encoding type {string, int}
 -o       The output filename
 -help    Print usage

Example

gonumerate --type UserType \
	--prefix UserType \
	--values Admin,Support \
	--json string \
	--sql string

This will produce the following file:

package gonumerate

import (
	"database/sql/driver"
	"encoding/json"
	"errors"
)

// UserType is an enumeration of values
type UserType int

// The UserType values
const (
	_ UserType = iota
	UserTypeAdmin
	UserTypeSupport
)

var userTypeStrings = map[UserType]string{
	UserTypeAdmin:   "admin",
	UserTypeSupport: "support",
}

// String returns a string representation of the UserType.
func (t UserType) String() string {
	if v, ok := userTypeStrings[t]; ok {
		return v
	}
	return ""
}

// UserTypeFromString returns the UserType from the given string.
func UserTypeFromString(s string) UserType {
	for k, v := range userTypeStrings {
		if v == s {
			return k
		}
	}
	return 0
}

// MarshalJSON marshals the UserType to JSON.
func (t UserType) MarshalJSON() ([]byte, error) {
	return json.Marshal(t.String())
}

// UnmarshalJSON unmarshals the UserType from JSON.
func (t *UserType) UnmarshalJSON(b []byte) error {
	var v string
	if err := json.Unmarshal(b, &v); err != nil {
		return err
	}
	*t = UserTypeFromString(v)
	return nil
}

// Value returns the UserType value for SQL encoding.
func (t *UserType) Value() (driver.Value, error) {
	return t.String(), nil
}

// Scan scans the UserType from its SQL encoded value.
func (t *UserType) Scan(v interface{}) error {
	bv, err := driver.String.ConvertValue(v)
	if err != nil {
		*t = 0
		return errors.New("failed to scan UserType")
	}

	if b, ok := bv.([]byte); ok {
		*t = UserTypeFromString(string(b))
		return nil
	} else if s, ok := bv.(string); ok {
		*t = UserTypeFromString(s)
		return nil
	} else {
		*t = 0
		return errors.New("failed to scan UserType")
	}
}

Go Generate

To use go generate, add the command as a comment to any .go file in your directory.

Example:

//go:generate gonumerate --type UserType --values Admin,Support

Then run:

go generate

For more information: https://blog.golang.org/generate

Other options

This is not the only enumeration generator written in Go. For other options, see:

• https://github.com/abice/go-enum
• https://github.com/alvaroloes/enumer
• https://github.com/steinfletcher/gonum