From e64b7cc233dcfdc2739eb478e4a82bdc8a942375 Mon Sep 17 00:00:00 2001
From: Matthias Kadenbach <matthias.kadenbach@gmail.com>
Date: Sun, 19 Feb 2017 15:51:12 -0800
Subject: [PATCH] explain dirty version error

---
 migrate.go      | 21 ++++++++++++++-------
 migrate_test.go | 10 +++++-----
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/migrate.go b/migrate.go
index a53f52f..2a620c0 100644
--- a/migrate.go
+++ b/migrate.go
@@ -29,7 +29,6 @@ var (
 	ErrNilVersion  = fmt.Errorf("no migration")
 	ErrLocked      = fmt.Errorf("database locked")
 	ErrLockTimeout = fmt.Errorf("timeout: can't acquire database lock")
-	ErrDirty       = fmt.Errorf("dirty database")
 )
 
 // ErrShortLimit is an error returned when not enough migrations
@@ -43,6 +42,14 @@ func (e ErrShortLimit) Error() string {
 	return fmt.Sprintf("limit %v short", e.Short)
 }
 
+type ErrDirty struct {
+	Version int
+}
+
+func (e ErrDirty) Error() string {
+	return fmt.Sprintf("Dirty database version %v. Fix and force version.", e.Version)
+}
+
 type Migrate struct {
 	sourceName   string
 	sourceDrv    source.Driver
@@ -210,7 +217,7 @@ func (m *Migrate) Migrate(version uint) error {
 	}
 
 	if dirty {
-		return m.unlockErr(ErrDirty)
+		return m.unlockErr(ErrDirty{curVersion})
 	}
 
 	ret := make(chan interface{}, m.PrefetchMigrations)
@@ -236,7 +243,7 @@ func (m *Migrate) Steps(n int) error {
 	}
 
 	if dirty {
-		return m.unlockErr(ErrDirty)
+		return m.unlockErr(ErrDirty{curVersion})
 	}
 
 	ret := make(chan interface{}, m.PrefetchMigrations)
@@ -263,7 +270,7 @@ func (m *Migrate) Up() error {
 	}
 
 	if dirty {
-		return m.unlockErr(ErrDirty)
+		return m.unlockErr(ErrDirty{curVersion})
 	}
 
 	ret := make(chan interface{}, m.PrefetchMigrations)
@@ -285,7 +292,7 @@ func (m *Migrate) Down() error {
 	}
 
 	if dirty {
-		return m.unlockErr(ErrDirty)
+		return m.unlockErr(ErrDirty{curVersion})
 	}
 
 	ret := make(chan interface{}, m.PrefetchMigrations)
@@ -317,13 +324,13 @@ func (m *Migrate) Run(migration ...*Migration) error {
 		return err
 	}
 
-	_, dirty, err := m.databaseDrv.Version()
+	curVersion, dirty, err := m.databaseDrv.Version()
 	if err != nil {
 		return m.unlockErr(err)
 	}
 
 	if dirty {
-		return m.unlockErr(ErrDirty)
+		return m.unlockErr(ErrDirty{curVersion})
 	}
 
 	ret := make(chan interface{}, m.PrefetchMigrations)
diff --git a/migrate_test.go b/migrate_test.go
index 21aa64c..0ec4bce 100644
--- a/migrate_test.go
+++ b/migrate_test.go
@@ -289,7 +289,7 @@ func TestMigrateDirty(t *testing.T) {
 	}
 
 	err := m.Migrate(1)
-	if err != ErrDirty {
+	if _, ok := err.(ErrDirty); !ok {
 		t.Fatalf("expected ErrDirty, got %v", err)
 	}
 }
@@ -370,7 +370,7 @@ func TestStepsDirty(t *testing.T) {
 	}
 
 	err := m.Steps(1)
-	if err != ErrDirty {
+	if _, ok := err.(ErrDirty); !ok {
 		t.Fatalf("expected ErrDirty, got %v", err)
 	}
 }
@@ -420,7 +420,7 @@ func TestUpDirty(t *testing.T) {
 	}
 
 	err := m.Up()
-	if err != ErrDirty {
+	if _, ok := err.(ErrDirty); !ok {
 		t.Fatalf("expected ErrDirty, got %v", err)
 	}
 }
@@ -433,7 +433,7 @@ func TestDownDirty(t *testing.T) {
 	}
 
 	err := m.Down()
-	if err != ErrDirty {
+	if _, ok := err.(ErrDirty); !ok {
 		t.Fatalf("expected ErrDirty, got %v", err)
 	}
 }
@@ -514,7 +514,7 @@ func TestRunDirty(t *testing.T) {
 	}
 
 	err = m.Run(migr)
-	if err != ErrDirty {
+	if _, ok := err.(ErrDirty); !ok {
 		t.Fatalf("expected ErrDirty, got %v", err)
 	}
 }