public DataContext() { var fileName = ConfigurationManager.AppSettings[GROUP]; Groups = (List <Group>)XmlFileReader.Deserialize(fileName, typeof(List <Group>)); fileName = ConfigurationManager.AppSettings[STUDENT]; Students = (List <Student>)XmlFileReader.Deserialize(fileName, typeof(List <Student>)); fileName = ConfigurationManager.AppSettings[ABSENT]; Absents = (List <Absent>)XmlFileReader.Deserialize(fileName, typeof(List <Absent>)); fileName = ConfigurationManager.AppSettings[SCHEDULE]; Schedules = (List <Schedule>)XmlFileReader.Deserialize(fileName, typeof(List <Schedule>)); fileName = ConfigurationManager.AppSettings[LESSON]; Lessons = (List <Lesson>)XmlFileReader.Deserialize(fileName, typeof(List <Lesson>)); }