New structure (#7)

pkg/models/list_users_update.go

@@ -0,0 +1,16 @@
+package models
+
+// Update updates a user <-> list relation
+func (lu *ListUser) Update() (err error) {
+
+	// Check if the right is valid
+	if err := lu.Right.isValid(); err != nil {
+		return err
+	}
+
+	_, err = x.
+		Where("list_id = ? AND user_id = ?", lu.ListID, lu.UserID).
+		Cols("right").
+		Update(lu)
+	return
+}