lowercase_string.go

lowercase_string.go

package main

import (
	"database/sql"
	"database/sql/driver"
	"errors"
	_ "github.com/go-sql-driver/mysql"
	"log"
	"strings"
)

type LowercaseString string

// Implements driver.Valuer.
func (ls LowercaseString) Value() (driver.Value, error) {
	return driver.Value(strings.ToLower(string(ls))), nil
}

// Implements sql.Scanner. Simplistic -- only handles string and []byte
func (ls *LowercaseString) Scan(src interface{}) error {
	var source string
	switch src.(type) {
	case string:
		source = src.(string)
	case []byte:
		source = string(src.([]byte))
	default:
		return errors.New("Incompatible type for LowercaseString")
	}
	*ls = LowercaseString(strings.ToLower(source))
	return nil
}

func main() {
	db, err := sql.Open("mysql",
		"root:@tcp(:3306)/test")
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	_, err = db.Exec(
		"CREATE TABLE IF NOT EXISTS test.hello(world varchar(50))")
	if err != nil {
		log.Fatal(err)
	}

	_, err = db.Exec("DELETE FROM test.hello")
	if err != nil {
		log.Fatal(err)
	}

	// Insert a row that's not lowercased, and one that is.
	var normalString string = "I AM UPPERCASED NORMAL STRING"
	var lcString LowercaseString = "I AM UPPERCASED MAGIC STRING"

	_, err = db.Exec("INSERT INTO test.hello VALUES(?), (?)", normalString, lcString)
	if err != nil {
		log.Fatal(err)
	}

	rows, err := db.Query("SELECT * FROM test.hello")
	if err != nil {
		log.Fatal(err)
	}
	defer rows.Close()
	for rows.Next() {
		var s1 LowercaseString
		err = rows.Scan(&s1)
		if err != nil {
			log.Print(err)
		}
		log.Print(s1)
	}
}