🧵 string-enumer

String enumer is a golang code generator for enums declared as strings.

The function func (v X) Valid() bool will always be generated on the defined types together with func XValues() []X. But options to generate more code exist. It is especially useful with the --text option, that generates an UnmarshalText function which forces any unmarshaling of the type (via for JSON/XML/etc.) to be limited to the defined types.

The tool is primarily intended to be used with go:generate, but can be used as a separate CLI tool.

Example usage with go generate

//go:generate string-enumer --text -t Country -o ./generated.go .
// or
//go:generate go run github.com/lindell/string-enumer --text -t Country -o ./generated.go .
type Country string

const (
	CountryCanada       Country = "CA"
	CountryChina        Country = "CN"
	CountrySweden       Country = "SE"
	CountryUnitedStates Country = "US"
)

When you run go generate for that package, it will generate:

// Valid validates if a value is a valid Country
func (v Country) Valid() bool {
	...
}

// CountryValues returns a list of all (valid) Country values
func CountryValues() []Country {
	...
}

// UnmarshalText takes a text, verifies that it is a correct Country and unmarshals it
func (v *Country) UnmarshalText(text []byte) error {
	...
}

(Please click this link for a real example at Go Playgrounds example)

CLI Description:

$ string-enumer --help
Usage of string-enumer:
	string-enumer [flags] --type T --type T2 [directory]
	string-enumer [flags] --type T --type T2 files... # Must be a single package
For more information, see:
	https://github.com/lindell/string-enumer
Flags:
  -o, --output string   output file name; default is stdout
  -T, --text            if set, text unmarshaling methods will be generated. Default: false
  -t, --type strings    the type name(s), can be multiple, but at least on must be set