add conversion interface; add struct derive support; add single mapping support

examples/conversion.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	_ "github.com/mattn/go-sqlite3"
+	"os"
+	. "xorm"
+)
+
+type Status struct {
+	Name  string
+	Color string
+}
+
+var (
+	Registed Status            = Status{"Registed", "white"}
+	Approved Status            = Status{"Approved", "green"}
+	Removed  Status            = Status{"Removed", "red"}
+	Statuses map[string]Status = map[string]Status{
+		Registed.Name: Registed,
+		Approved.Name: Approved,
+		Removed.Name:  Removed,
+	}
+)
+
+func (s *Status) FromDB(bytes []byte) error {
+	if r, ok := Statuses[string(bytes)]; ok {
+		*s = r
+		return nil
+	} else {
+		return errors.New("no this data")
+	}
+}
+
+func (s *Status) ToDB() ([]byte, error) {
+	return []byte(s.Name), nil
+}
+
+type User struct {
+	Id     int64
+	Name   string
+	Status Status `xorm:"varchar(40)"`
+}
+
+func main() {
+	f := "conversion.db"
+	os.Remove(f)
+
+	Orm, err := NewEngine("sqlite3", f)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	Orm.ShowSQL = true
+	err = Orm.CreateTables(&User{})
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	_, err = Orm.Insert(&User{1, "xlw", Registed})
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	users := make([]User, 0)
+	err = Orm.Find(&users)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	fmt.Println(users)
+}

session.go

@@ -225,6 +225,12 @@ func (session *Session) scanMapIntoStruct(obj interface{}, objMap map[string][]b
 				}
 
 				v = x
+			} else if structConvert, ok := structField.Addr().Interface().(Conversion); ok {
+				err := structConvert.FromDB(data)
+				if err != nil {
+					return err
+				}
+				continue
 			} else if session.Statement.UseCascade {
 				table := session.Engine.AutoMapType(structField.Type())
 				if table != nil {
@@ -710,6 +716,13 @@ func (session *Session) InsertOne(bean interface{}) (int64, error) {
 			} else {
 				continue
 			}
+		} else if fieldConvert, ok := fieldValue.Addr().Interface().(Conversion); ok {
+			data, err := fieldConvert.ToDB()
+			if err != nil {
+				return 0, err
+			} else {
+				args = append(args, string(data))
+			}
 		} else {
 			args = append(args, val)
 		}

table.go

@@ -94,3 +94,8 @@ type Table struct {
 func (table *Table) PKColumn() Column {
 	return table.Columns[table.PrimaryKey]
 }
+
+type Conversion interface {
+	FromDB([]byte) error
+	ToDB() ([]byte, error)
+}