add mysql adaptor

Author: braindev

adaptor/mysql.go

@@ -0,0 +1,69 @@
+package adaptor
+
+import (
+	"database/sql"
+
+	"bitbucket.org/braindev/dbmigrate"
+)
+
+// MySQLAdaptor is a PostgreSQL DBMigrate adaptor
+type MySQLAdaptor struct {
+	db *sql.DB
+}
+
+// NewMySQL creates a new PostgresAdaptor
+func NewMySQL(db *sql.DB) (*MySQLAdaptor, error) {
+	a := &MySQLAdaptor{
+		db: db,
+	}
+	return a, a.createMigrationsTable()
+}
+
+// GetAppliedMigrationsOrderedAsc returns an ordered slice of string versions
+// of migrations that have been previously applied
+func (a *MySQLAdaptor) GetAppliedMigrationsOrderedAsc() ([]string, error) {
+	const query = "SELECT `version` FROM `dbmigrations` ORDER BY `version` ASC"
+	rows, err := a.db.Query(query)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var version string
+	versions := []string{}
+	for rows.Next() {
+		err = rows.Scan(&version)
+		if err != nil {
+			return nil, err
+		}
+		versions = append(versions, version)
+	}
+	return versions, nil
+}
+
+// createMigrationsTable conditionally creates the migrations table if it
+// doesn't yet exist
+func (a *MySQLAdaptor) createMigrationsTable() error {
+	const query = "CREATE TABLE IF NOT EXISTS `dbmigrations`(`version` varchar NOT NULL PRIMARY KEY)"
+	_, err := a.db.Exec(query)
+	return err
+}
+
+// ApplyMigration applies the specified migration
+func (a *MySQLAdaptor) ApplyMigration(pair dbmigrate.MigrationPair) error {
+	_, err := a.db.Exec(pair.ApplyBody)
+	if err != nil {
+		return err
+	}
+	_, err = a.db.Exec("INSERT INTO `dbmigrations` (`version`) VALUES (?)", pair.Version)
+	return err
+}
+
+// RollbackMigration rolls back the specifified migration
+func (a *MySQLAdaptor) RollbackMigration(pair dbmigrate.MigrationPair) error {
+	_, err := a.db.Exec(pair.RollbackBody)
+	if err != nil {
+		return err
+	}
+	_, err = a.db.Exec("DELETE FROM `dbmigrations` WHERE `version` = ?", pair.Version)
+	return nil
+}