encapsulate ErrNotFound

session.go

@@ -6,6 +6,10 @@ import (
 	mgo "gopkg.in/mgo.v2"
 )
 
+var (
+	ErrNotFound = errors.New("not found")
+)
+
 type Session struct {
 	session *mgo.Session
 }
@@ -14,6 +18,10 @@ func (s *Session) Close() {
 	s.session.Close()
 }
 
+func (s *Session) Copy() *Session {
+	return &Session{session: s.session.Copy()}
+}
+
 func NewSession(dial string) (*Session, error) {
 	session, err := mgo.Dial(dial)
 	if err != nil {
@@ -105,7 +113,11 @@ func (q *Query) Select(selector interface{}) *Query {
 }
 
 func (q *Query) One(result interface{}) error {
-	return q.query.One(result)
+	err := q.query.One(result)
+	if err == mgo.ErrNotFound {
+		err = ErrNotFound
+	}
+	return err
 }
 
 func (q *Query) Sort(fields ...string) *Query {
@@ -124,11 +136,19 @@ func (q *Query) Limit(n int) *Query {
 }
 
 func (q *Query) All(result interface{}) error {
-	return q.query.All(result)
+	err := q.query.All(result)
+	if err == mgo.ErrNotFound {
+		err = ErrNotFound
+	}
+	return err
 }
 
 func (q *Query) Count() (int, error) {
-	return q.query.Count()
+	c, err := q.query.Count()
+	if err == mgo.ErrNotFound {
+		err = ErrNotFound
+	}
+	return c, err
 }
 
 type Index struct {
@@ -151,7 +171,11 @@ type Pipe struct {
 }
 
 func (p *Pipe) All(result interface{}) error {
-	return p.pipe.All(result)
+	err := p.pipe.All(result)
+	if err == mgo.ErrNotFound {
+		err = ErrNotFound
+	}
+	return err
 }
 
 func (c *Collection) Pipe(pipeline interface{}) *Pipe {