Allow to select the database name for every collection.

Usefull if you want to allow people to switch databases.

collection.go

@@ -63,6 +63,7 @@ func (v *ValidationError) Error() string {
 
 type Collection struct {
 	Name       string
+	Database   string
 	Context    *Context
 	Connection *Connection
 }
@@ -78,12 +79,14 @@ func (d DocumentNotFoundError) Error() string {
 	return "Document not found"
 }
 
+// Collection ...
 func (c *Collection) Collection() *mgo.Collection {
-	return c.Connection.Session.DB(c.Connection.Config.Database).C(c.Name)
+	return c.Connection.Session.DB(c.Database).C(c.Name)
 }
 
+// CollectionOnSession ...
 func (c *Collection) collectionOnSession(sess *mgo.Session) *mgo.Collection {
-	return sess.DB(c.Connection.Config.Database).C(c.Name)
+	return sess.DB(c.Database).C(c.Name)
 }
 
 func (c *Collection) PreSave(doc Document) error {

main.go

@@ -59,7 +59,6 @@ func (m *Connection) Connect() (err error) {
 	}
 
 	session, err := mgo.DialWithInfo(m.Config.DialInfo)
-
 	if err != nil {
 		return err
 	}
@@ -71,12 +70,18 @@ func (m *Connection) Connect() (err error) {
 	return nil
 }
 
-func (m *Connection) Collection(name string) *Collection {
-
-	// Just create a new instance - it's cheap and only has name
+// CollectionFromDatabase ...
+func (m *Connection) CollectionFromDatabase(name string, database string) *Collection {
+	// Just create a new instance - it's cheap and only has name and a database name
 	return &Collection{
 		Connection: m,
-		Name:       name,
 		Context:    m.Context,
+		Database:   database,
+		Name:       name,
 	}
 }
+
+// Collection ...
+func (m *Connection) Collection(name string) *Collection {
+	return m.CollectionFromDatabase(name, m.Config.Database)
+}

main_test.go

@@ -59,9 +59,29 @@ func TestRetrieveCollection(t *testing.T) {
 	Convey("should be able to retrieve a collection instance from a connection", t, func() {
 		conn := getConnection()
 		defer conn.Session.Close()
-		col := conn.Collection("tests")
-
+		col := conn.Collection("tests");
 		So(col.Name, ShouldEqual, "tests")
 		So(col.Connection, ShouldEqual, conn)
+
+		So(col.Context.Get("foo"), ShouldEqual, "bar")
+
+		So(conn.Config.Database, ShouldEqual, col.Database)
+	})
+	Convey("should be able to retrieve a collection instance from a connection with different databases", t, func() {
+		conn := getConnection()
+		defer conn.Session.Close()
+
+		col1 := conn.CollectionFromDatabase("tests", "test1");
+		So(col1.Name, ShouldEqual, "tests")
+		So(col1.Connection, ShouldEqual, conn)
+		So(col1.Database, ShouldEqual, "test1")
+
+		col2 := conn.CollectionFromDatabase("tests", "test2");
+		So(col2.Name, ShouldEqual, "tests")
+		So(col2.Connection, ShouldEqual, conn)
+		So(col2.Database, ShouldEqual, "test2")
+
+		So(col2.Connection, ShouldEqual, col1.Connection)
+		So(col1.Database, ShouldNotEqual, col2.Database)
 	})
 }

resultSet.go

@@ -74,7 +74,7 @@ func (r *ResultSet) Paginate(perPage, page int) (*PaginationInfo, error) {
 	// Get count on a different session to avoid blocking
 	sess := r.Collection.Connection.Session.Copy()
 
-	count, err := sess.DB(r.Collection.Connection.Config.Database).C(r.Collection.Name).Find(r.Params).Count()
+	count, err := sess.DB(r.Collection.Database).C(r.Collection.Name).Find(r.Params).Count()
 	sess.Close()
 
 	if err != nil {