go-sfgen

See https://pkg.go.dev/github.com/rad12000/go-sfgen for detailed documentation.

go-sfgen is a command line tool, designed to be used in // go:generate directives. It aims to remove the boilerplate of creating const values that match tag name values. For example:

package main

type Person struct {
	FullName string `db:"full_name"`
	Age     int     `db:"age"`
}

const (
	DBColFullName = "full_name"
	DBColAge      = "age"
)

becomes

// -- main.go --
//go:generate go-sfgen --struct Person --tag db --prefix DBCol --export
package main

type Person struct {
	FullName string `db:"full_name"`
	Age     int     `db:"age"`
}

// -- person_dbcol_generated.go --
const (
	DBColFullName = "full_name"
	DBColAge      = "age"
)

it can also generate new types, type aliases, and generic types for type safety:

Alias

// -- main.go --
//go:generate go-sfgen --style alias --struct Person --tag db prefix DBCol --export
package main

type Person struct {
	FullName string `db:"full_name"`
	Age     int     `db:"age"`
}

// -- person_dbcol_generated.go --
type DBCol = string
const (
	DBColFullName DBCol = "full_name"
	DBColAge      DBCol = "age"
)

Type

// -- main.go --
//go:generate go-sfgen --style typed --struct Person --tag db --prefix DBCol --export
package main

type Person struct {
	FullName string `db:"full_name"`
	Age     int     `db:"age"`
}

// -- person_dbcol_generated.go --
type DBCol string
func (d DBCol) String() string {
	return (string)(d)
}

const (
	DBColFullName DBCol = "full_name"
	DBColAge      DBCol = "age"
)

Generic

// -- main.go --
//go:generate go-sfgen --style typed --struct Person --tag db --prefix DBCol --export
package main

type Person struct {
	FullName string `db:"full_name"`
	Age     int     `db:"age"`
}

// -- person_dbcol_generated.go --
type DBCol[T any] string
func (d DBCol[T]) String() string {
	return (string)(d)
}

const (
	DBColFullName DBCol[string] = "full_name"
	DBColAge      DBCol[int] = "age"
)

One can also generate enum-like values from a struct:

// -- main.go --
//go:generate go-sfgen --style typed --iter --struct Person --export
package main

type Person struct {
	FullName string `db:"full_name"`
	Age     int     `db:"age"`
}

// -- person_dbcol_generated.go --
type Field string
func (f Field) String() string {
	return (string)(f)
}

func (F Field) All() [2]string {
	return [2]string{"FullName", "Age"}
}

const (
	FieldFullName Field = "FullName"
	FieldAge      Field = "Age"
)