update

calendar/event.go

@@ -37,6 +37,16 @@ func (e *Event) BeforeSave(tx *gorm.DB) (err error) {
 		tx.Raw("select name from calendars where id = ?", e.CalendarID).Scan(&loc)
 		e.Location = loc
 	}
+
+	// test for collide
+	cnt := 0
+	db.Raw(`select count(*) from events e where 
+		(? >= "start" and ? <= "end" )
+		or
+		(? >= "start" and ? <= "end"  )
+		and calendar_id = ?`,
+		e.End, e.End, e.Start, e.Start, e.CalendarID).Scan(&cnt)
+
 	return
 }