go
sqlx
enum type
#TIL 22 - Enum Type with PostgreSQL and sqlx
Why
This is a solution when I need to have a custom scan for enum type
How
Let's say, we will have ProjectSector as enum on PostgreSQL DB.
type ProjectSector string
type SourceEntity struct {
...
ProjectSectors ProjectSectors `json:"project_sectors" db:"project_sectors"`
}
func parseEnumFormat(str []byte) string {
if len(str) == 0 {
return ""
}
// remove {} from enum
val := string(str[1 : len(str)-1])
return removeAllQuotesFromStr(val)
}
// Remove the quotes from the enum
func removeAllQuotesFromStr(str string) string {
if len(str) == 0 {
return ""
}
// remove quotes from enum
val := strings.Replace(str, "\"", "", -1)
return val
}
func (ps *ProjectSector) Scan(val interface{}) error {
switch v := val.(type) {
case []byte:
*ps = ProjectSector(parseEnumFormat(v))
return nil
default:
return fmt.Errorf("UNSUPPORTED TYPE: %T", v)
}
}
Then if you want to work with enum slice
type ProjectSectors []ProjectSector
func (ps *ProjectSectors) Scan(val interface{}) (err error) {
list := []ProjectSector{}
if val == nil {
*ps = list
return
}
v := val.([]byte)
sectorsArray := strings.Split(parseEnumFormat(v), ",")
// make unique
keys := make(map[string]bool)
for i := 0; i < len(sectorsArray); i++ {
if _, value := keys[sectorsArray[i]]; !value {
keys[sectorsArray[i]] = true
list = append(list, ProjectSector(sectorsArray[i]))
}
}
*ps = list
return
}
func (ps ProjectSectors) Value() (driver.Value, error) {
if ps == nil {
return "", nil
}
// remove [] from enum
enumStrArray := make([]string, len(ps))
for i, sector := range ps {
// add quotes to enum if contain spaces
if strings.Contains(string(sector), " ") {
enumStrArray[i] = fmt.Sprintf("\"%s\"", sector)
} else {
enumStrArray[i] = string(sector)
}
}
println(strings.Join(enumStrArray, ","))
return fmt.Sprintf(`{%s}`, strings.Join(enumStrArray, ",")), nil
}
