Add AutoMigrate Support

README.md

@@ -14,6 +14,7 @@ Yet Another ORM library for Go, aims for developer friendly
 * Automatically CreatedAt, UpdatedAt
 * Soft Delete
 * Create/Drop table from struct
+* Automating Migrations
 * Dynamically set table name when search, create, update, delete...
 * Prevent SQL Injection
 * Goroutines friendly
@@ -97,6 +98,18 @@ db.CreateTable(User{})
 db.DropTable(User{})
 ```
 
+### Automating Migrations
+
+Feel Free to update your struct, AutoMigrate will keep your database update to date.
+
+FYI, AutoMigrate will only add new columns, won't change column's type or delete unused columns, to make sure gorm won't harm your data.
+
+If table doesn't exist when AutoMigrate, it will run create table automatically.
+
+```go
+db.AutoMigrate(User{})
+```
+
 ## Create
 
 ```go

chain.go

@@ -236,17 +236,17 @@ func (s *Chain) Or(querystring interface{}, args ...interface{}) *Chain {
 }
 
 func (s *Chain) CreateTable(value interface{}) *Chain {
-	s.do(value).createTable().exec()
+	s.do(value).createTable()
 	return s
 }
 
 func (s *Chain) DropTable(value interface{}) *Chain {
-	s.do(value).dropTable().exec()
+	s.do(value).dropTable()
 	return s
 }
 
 func (s *Chain) AutoMigrate(value interface{}) *Chain {
-	s.do(value).autoMigrate().exec()
+	s.do(value).autoMigrate()
 	return s
 }
 

do.go

@@ -715,6 +715,7 @@ func (s *Do) createTable() *Do {
 		s.tableName(),
 		strings.Join(sqls, ","),
 	)
+	s.exec()
 	return s
 }
 
@@ -723,13 +724,32 @@ func (s *Do) dropTable() *Do {
 		"DROP TABLE %v",
 		s.tableName(),
 	)
+	s.exec()
 	return s
 }
 
 func (s *Do) autoMigrate() *Do {
-	sql := fmt.Sprintf("SELECT column_name, data_type FROM information_schema.columns WHERE table_name = %v", s.tableName())
-	for _, field := range s.model.fields("other") {
-		s.sql = fmt.Sprintf(sql+"and column_name = %v", field.DbName)
+	var table_name string
+	sql := fmt.Sprintf("SELECT table_name FROM INFORMATION_SCHEMA.tables where table_name = %v", s.addToVars(s.tableName()))
+	s.db.QueryRow(sql, s.sqlVars...).Scan(&table_name)
+	s.sqlVars = []interface{}{}
+
+	// If table doesn't exist
+	if len(table_name) == 0 {
+		s.createTable()
+	} else {
+		for _, field := range s.model.fields("other") {
+			var column_name, data_type string
+			sql := fmt.Sprintf("SELECT column_name, data_type FROM information_schema.columns WHERE table_name = %v", s.addToVars(s.tableName()))
+			s.db.QueryRow(fmt.Sprintf(sql+" and column_name = %v", s.addToVars(field.DbName)), s.sqlVars...).Scan(&column_name, &data_type)
+			s.sqlVars = []interface{}{}
+
+			// If column doesn't exist
+			if len(column_name) == 0 {
+				s.sql = fmt.Sprintf("ALTER TABLE %v ADD %v %v", s.tableName(), field.DbName, field.SqlType)
+				s.exec()
+			}
+		}
 	}
 	return s
 }

gorm_test.go

@@ -38,13 +38,12 @@ type CreditCard struct {
 }
 
 type Email struct {
-	Id         int64
-	UserId     int64
-	Email      string
-	Subscribed bool
-	CreatedAt  time.Time
-	UpdatedAt  time.Time
-	DeletedAt  time.Time
+	Id        int64
+	UserId    int64
+	Email     string
+	CreatedAt time.Time
+	UpdatedAt time.Time
+	DeletedAt time.Time
 }
 
 type Address struct {
@@ -1236,6 +1235,32 @@ func TestTableName(t *testing.T) {
 	}
 }
 
+type BigEmail struct {
+	Id           int64
+	UserId       int64
+	Email        string
+	UserAgent    string
+	RegisteredAt time.Time
+	CreatedAt    time.Time
+	UpdatedAt    time.Time
+	DeletedAt    time.Time
+}
+
+func (b BigEmail) TableName() string {
+	return "emails"
+}
+
 func TestAutoMigration(t *testing.T) {
 	db.AutoMigrate(Address{})
+	if err := db.Table("emails").AutoMigrate(BigEmail{}).Error; err != nil {
+		t.Errorf("Auto Migrate should not raise any error", err)
+	}
+
+	db.Save(&BigEmail{Email: "jinzhu@example.org", UserAgent: "pc", RegisteredAt: time.Now()})
+
+	var big_email BigEmail
+	db.First(&big_email, "user_agent = ?", "pc")
+	if big_email.Email != "jinzhu@example.org" || big_email.UserAgent != "pc" || big_email.RegisteredAt.IsZero() {
+		t.Error("Big Emails should be saved and fetched correctly")
+	}
 }