uuid.go

package slices

import (
	"database/sql/driver"
	"encoding/json"
	"fmt"
	"strings"

	"errors"

	"github.com/gofrs/uuid"
)

// For reading in arrays from postgres

// UUID is a slice of UUIDs.
type UUID []uuid.UUID

// Interface implements the nulls.nullable interface.
func (s UUID) Interface() interface{} {
	return []uuid.UUID(s)
}

// Scan implements the sql.Scanner interface.
// It allows to read the UUID slice from the database value.
func (s *UUID) Scan(src interface{}) error {
	b, ok := src.([]byte)
	if !ok {
		return errors.New("scan source was not []byte")
	}
	us, err := strSliceToUUIDSlice(strToUUID(string(b)))
	if err != nil {
		return err
	}
	*s = us
	return nil
}

// Value implements the driver.Valuer interface.
// It allows to convert the UUID slice to a driver.value.
func (s UUID) Value() (driver.Value, error) {
	ss := make([]string, len(s))
	for i, u := range s {
		ss[i] = u.String()
	}
	return fmt.Sprintf("{%s}", strings.Join(ss, ",")), nil
}

// UnmarshalJSON will unmarshall JSON value into
// the UUID slice representation of this value.
func (s *UUID) UnmarshalJSON(data []byte) error {
	var ss []string
	if err := json.Unmarshal(data, &ss); err != nil {
		return err
	}
	us, err := strSliceToUUIDSlice(ss)
	if err != nil {
		return err
	}
	*s = us
	return nil
}

// UnmarshalText will unmarshall text value into
// the UUID slice representation of this value.
func (s *UUID) UnmarshalText(text []byte) error {
	var ss []string
	for _, x := range strings.Split(string(text), ",") {
		ss = append(ss, strings.TrimSpace(x))
	}
	us, err := strSliceToUUIDSlice(ss)
	if err != nil {
		return err
	}
	*s = us
	return nil
}

// TagValue implements the tagValuer interface, to work with https://github.com/gobuffalo/tags.
func (s UUID) TagValue() string {
	return s.Format(",")
}

// Format presents the slice as a string, using a given separator.
func (s UUID) Format(sep string) string {
	ss := make([]string, len(s))
	for i, u := range s {
		ss[i] = u.String()
	}
	return strings.Join(ss, sep)
}

func strToUUID(s string) []string {
	r := strings.Trim(s, "{}")
	return strings.Split(r, ",")
}

func strSliceToUUIDSlice(ss []string) (UUID, error) {
	us := make([]uuid.UUID, len(ss))
	for i, s := range ss {
		if s == "" {
			continue
		}
		u, err := uuid.FromString(s)
		if err != nil {
			return UUID{}, err
		}
		us[i] = u
	}
	return UUID(us), nil
}