dbmate/mysql.go
2017-05-04 20:58:23 -07:00

149 lines
3.4 KiB
Go

package dbmate
import (
"database/sql"
"fmt"
"net/url"
"strings"
_ "github.com/go-sql-driver/mysql" // mysql driver for database/sql
)
// MySQLDriver provides top level database functions
type MySQLDriver struct {
}
func normalizeMySQLURL(u *url.URL) string {
normalizedURL := *u
normalizedURL.Scheme = ""
normalizedURL.Host = fmt.Sprintf("tcp(%s)", normalizedURL.Host)
query := normalizedURL.Query()
query.Set("multiStatements", "true")
normalizedURL.RawQuery = query.Encode()
str := normalizedURL.String()
return strings.TrimLeft(str, "/")
}
// Open creates a new database connection
func (drv MySQLDriver) Open(u *url.URL) (*sql.DB, error) {
return sql.Open("mysql", normalizeMySQLURL(u))
}
func (drv MySQLDriver) openRootDB(u *url.URL) (*sql.DB, error) {
// connect to no particular database
rootURL := *u
rootURL.Path = "/"
return drv.Open(&rootURL)
}
func quoteIdentifier(str string) string {
str = strings.Replace(str, "`", "\\`", -1)
return fmt.Sprintf("`%s`", str)
}
// CreateDatabase creates the specified database
func (drv MySQLDriver) CreateDatabase(u *url.URL) error {
name := databaseName(u)
fmt.Printf("Creating: %s\n", name)
db, err := drv.openRootDB(u)
if err != nil {
return err
}
defer mustClose(db)
_, err = db.Exec(fmt.Sprintf("create database %s",
quoteIdentifier(name)))
return err
}
// DropDatabase drops the specified database (if it exists)
func (drv MySQLDriver) DropDatabase(u *url.URL) error {
name := databaseName(u)
fmt.Printf("Dropping: %s\n", name)
db, err := drv.openRootDB(u)
if err != nil {
return err
}
defer mustClose(db)
_, err = db.Exec(fmt.Sprintf("drop database if exists %s",
quoteIdentifier(name)))
return err
}
// DatabaseExists determines whether the database exists
func (drv MySQLDriver) DatabaseExists(u *url.URL) (bool, error) {
name := databaseName(u)
db, err := drv.openRootDB(u)
if err != nil {
return false, err
}
defer mustClose(db)
exists := false
err = db.QueryRow(`select true from information_schema.schemata
where schema_name = ?`, name).Scan(&exists)
if err == sql.ErrNoRows {
return false, nil
}
return exists, err
}
// CreateMigrationsTable creates the schema_migrations table
func (drv MySQLDriver) CreateMigrationsTable(db *sql.DB) error {
_, err := db.Exec(`create table if not exists schema_migrations (
version varchar(255) primary key)`)
return err
}
// SelectMigrations returns a list of applied migrations
// with an optional limit (in descending order)
func (drv MySQLDriver) SelectMigrations(db *sql.DB, limit int) (map[string]bool, error) {
query := "select version from schema_migrations order by version desc"
if limit >= 0 {
query = fmt.Sprintf("%s limit %d", query, limit)
}
rows, err := db.Query(query)
if err != nil {
return nil, err
}
defer mustClose(rows)
migrations := map[string]bool{}
for rows.Next() {
var version string
if err := rows.Scan(&version); err != nil {
return nil, err
}
migrations[version] = true
}
return migrations, nil
}
// InsertMigration adds a new migration record
func (drv MySQLDriver) InsertMigration(db Transaction, version string) error {
_, err := db.Exec("insert into schema_migrations (version) values (?)", version)
return err
}
// DeleteMigration removes a migration record
func (drv MySQLDriver) DeleteMigration(db Transaction, version string) error {
_, err := db.Exec("delete from schema_migrations where version = ?", version)
return err
}