Make it possible to run migrations as a library

cmd/perform.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/andrewpillar/mgrt/config"
 	"github.com/andrewpillar/mgrt/database"
+	"github.com/andrewpillar/mgrt/migration"
 	"github.com/andrewpillar/mgrt/revision"
 	"github.com/andrewpillar/mgrt/util"
 )
@@ -34,15 +35,15 @@ func loadRevisions(c cli.Command, d revision.Direction) ([]*revision.Revision, e
 	var err error
 
 	switch d {
-		case revision.Up:
-			revisions, err = revision.Oldest()
-			break
-		case revision.Down:
-			revisions, err = revision.Latest()
-			break
-		default:
-			err = errors.New("unknown direction")
-			break
+	case revision.Up:
+		revisions, err = revision.Oldest()
+		break
+	case revision.Down:
+		revisions, err = revision.Latest()
+		break
+	default:
+		err = errors.New("unknown direction")
+		break
 	}
 
 	return revisions, err
@@ -83,38 +84,8 @@ func perform(c cli.Command, d revision.Direction) {
 
 	force := c.Flags.IsSet("force")
 
-	for _, r := range revisions {
-		r.Direction = d
-
-		if err := r.GenHash(); err != nil {
-			util.ExitError("failed to perform revision", err)
-		}
-
-		if err := db.Perform(r, force); err != nil {
-			if err != database.ErrAlreadyPerformed {
-				util.ExitError("failed to perform revision", fmt.Errorf("%s: %d", err, r.ID))
-			}
-
-			fmt.Printf("%s - %s: %d", d, err, r.ID)
-
-			if r.Message != "" {
-				fmt.Printf(": %s", r.Message)
-			}
-
-			fmt.Printf("\n")
-			continue
-		}
-
-		if err := db.Log(r, force); err != nil {
-			util.ExitError("failed to log revision", err)
-		}
-
-		fmt.Printf("%s - performed revision: %d", d, r.ID)
-
-		if r.Message != "" {
-			fmt.Printf(": %s", r.Message)
-		}
-
-		fmt.Printf("\n")
+	err = migration.Perform(db, revisions, d, force)
+	if err != nil {
+		util.ExitError("failed to perform revision ", err)
 	}
 }

database/mysql.go

@@ -55,6 +55,12 @@ func init() {
 	databases["mysql"] = &MySQL{}
 }
 
+func (p *MySQL) FromConn(db *sql.DB) {
+	p.database = &database{
+		DB: db,
+	}
+}
+
 func (m *MySQL) Open(cfg *config.Config) error {
 	dsn := fmt.Sprintf(mysqlDsn, cfg.Username, cfg.Password, cfg.Address, cfg.Database)
 

database/postgres.go

@@ -52,6 +52,12 @@ func init() {
 	databases["postgres"] = &Postgres{}
 }
 
+func (p *Postgres) FromConn(db *sql.DB) {
+	p.database = &database{
+		DB: db,
+	}
+}
+
 func (p *Postgres) Open(cfg *config.Config) error {
 	host, port, err := net.SplitHostPort(cfg.Address)
 

database/sqlite3.go

@@ -32,6 +32,12 @@ func init() {
 	databases["sqlite3"] = &SQLite3{}
 }
 
+func (p *SQLite3) FromConn(db *sql.DB) {
+	p.database = &database{
+		DB: db,
+	}
+}
+
 func (s *SQLite3) Open(cfg *config.Config) error {
 	db, err := sql.Open("sqlite3", cfg.Address)
 

migration/migrate.go

@@ -0,0 +1,47 @@
+package migration
+
+import (
+	"fmt"
+
+	"github.com/andrewpillar/mgrt/database"
+	"github.com/andrewpillar/mgrt/revision"
+)
+
+func Perform(db database.DB, revisions []*revision.Revision, d revision.Direction, force bool) error {
+	for _, r := range revisions {
+
+		r.Direction = d
+
+		if err := r.GenHash(); err != nil {
+			return err
+		}
+
+		if err := db.Perform(r, force); err != nil {
+			if err != database.ErrAlreadyPerformed {
+				return fmt.Errorf("%s: %d", err, r.ID)
+			}
+
+			fmt.Printf("%s - %s: %d", d, err, r.ID)
+
+			if r.Message != "" {
+				fmt.Printf(": %s", r.Message)
+			}
+
+			fmt.Printf("\n")
+			continue
+		}
+
+		if err := db.Log(r, force); err != nil {
+			return err
+		}
+
+		fmt.Printf("%s - performed revision: %d", d, r.ID)
+
+		if r.Message != "" {
+			fmt.Printf(": %s", r.Message)
+		}
+
+		fmt.Printf("\n")
+	}
+	return nil
+}

revision/revision.go

@@ -17,8 +17,8 @@ import (
 )
 
 var (
-	upFile      = "up.sql"
-	downFile    = "down.sql"
+	upFile   = "up.sql"
+	downFile = "down.sql"
 
 	reslug = regexp.MustCompile("[^a-zA-Z0-9]")
 	redup  = regexp.MustCompile("-{2,}")
@@ -196,6 +196,10 @@ func Find(id string) (*Revision, error) {
 		}
 	}
 
+	if base == "" {
+		return nil, errors.New("no revision found with ID: " + id)
+	}
+
 	return resolveFromPath(filepath.Join(config.RevisionsDir(), base))
 }