OOP and files handling python programming project

class Student :
    def __init__(self,ID,Firstname,Familyname,absence,Exam1,Exam2) :
        """initializes the student; Add new Student"""
        self._ID = ID
        self._FirstName = Firstname
        self._FamilyName = Familyname
        self._absences = absence
        self._Exam1= Exam1
        self._Exam2= Exam2
        self._TotalGrade= int(Exam1)+int(Exam2)

    def getID(self):
        return self._ID

    def get_name(self):
        """ returns the student name"""
        return self._FirstName+' '+self._FamilyName
    def get_absence(self):
        return self._absences
    def get_exam1(self):
        """get exam1  grade  """
        return self._Exam1
    def get_exam2(self):
        """get exam2  grade """
        return self._Exam2
    def set_ID(self,ID):
         self._ID=ID
    def set_name(self,Name):
        """ set the student name"""
        self._FirstName ,self._FamilyName = Name.split()
    def set_absence(self,absence):
        self._absences=absence
    def set_exam1(self,Exam1):
        """set exam1  grade  """
        self._Exam1 = Exam1
    def set_exam2(self,Exam2):
        """get exam2  grade """
        self._Exam2 = Exam2
    def calculate_total(self):
        """get exam2  grade """
        return self._Exam1+self._Exam2
    def PrintStudent(self):
        print(self._FirstName+',  '+self._FamilyName+',  '+self._absences+', '+self._Exam1+', '+self._Exam2+', '+str(self._TotalGrade)+'\n')


class Class :
    def __init__(self):
        """Sets up a class to hold and update students"""
        self.students = []
    def addStudent(self,ID,Firstname,Familyname,absence,Exam1,Exam2):
        student = Student(ID,Firstname,Familyname,absence,Exam1,Exam2)
        self.students.append(student)
    def delStudent(self,student):
        self.students.remove(student)
    def getStudentByID(self,ID):
        for student in self.students:
            if student._ID == ID:
                return student
    def getStudentByName(self,FirstName):
        StudentsByName = []
        for student in self.students:
            if student._FirstName == FirstName:
                StudentsByName.append(student)
        return StudentsByName
    
    def modifyStudentID(self,Student,newID):
        Student.set_ID(newID)
        return Student
    def modifyStudentName(self,Student,newName):
        Student.set_name(newName)
        return Student
    def modifyStudentAbsence(self,Student,newAbsence):
        Student.set_absence(newAbsence)
        return Student
    def modifyStudentExam1(self,student,newExam1):
        student.set_exam1(newExam1)
        return student
    def modifyStudentExam2(self,student,newExam2):
        student.set_exam2(newID)
        return student
    def modifyStudent(self,student):
        EditedStudent = Student(student._ID,student._Firstname,student._Familyname,student._absence,student._Exam1,student._Exam2)
        delStudent(student)
        addStudent(EditedStudent)
        
    def ShowByID(self):
        return sorted(self.students, key= lambda e:e._ID)
    def ShowByName(self):
        return sorted(self.students, key= lambda e:e._FirstName)
    def ShowByAbsences(self):
        return sorted(self.students, key= lambda e:e._absences, reverse=True)
    def ShowByTotal(self):
        return sorted(self.students, key= lambda e:e._TotalGrade, reverse=True)
    def GetStudentAbsences(self):
        AbsentStudent= self.students[0]
        for student in self.students:
            if(student._absences>AbsentStudent._absences):
                AbsentStudent=student
        return AbsentStudent

def read_data(filename):
    c = Class()
    with open(filename, "r") as ClassStudents:
        for line in ClassStudents:
            ID,Firstname,Familyname,absence,Exam1,Exam2,total = line.strip().split(',')
            c.addStudent(ID,Firstname,Familyname,absence,Exam1,Exam2)
    return c

def Save_Quit(Students,filename):
    f = open(filename, "w")
    for student in Students:
        line=student._ID+','+student._FirstName+','+student._FamilyName+','+student._absences+','+student._Exam1+','+student._Exam2+','+str(student._TotalGrade)+'\n'
        f.write(line)
    print('Students data Saved!')
    f.close()
    
def TestAttribute(Att,type):
    if Att == '':
        return 'You cannot skip this attribute!\n'
    if type == 'int':
        if not Att.isnumeric():
            return 'Enter only numeric values Please!'
    elif type == 'str':
        if not Att.replace(" ", "").isalpha():
            if "'" not in Att:
                return 'Enter only Alphabetic values Please!'
                
def add_new_student(c):
    ID = input('Enter Student ID:')
    while TestAttribute(ID,'int'):
        print(TestAttribute(ID, 'int'))
        ID = input('Enter Student ID:')
    firstname = input('Enter Student Firstname:')
    while TestAttribute(firstname,'str'):
        print(TestAttribute(firstname, 'str'))
        firstname = input('Enter Student Firstname:')
    familyname = input('Enter Student Familyname:')
    while TestAttribute(familyname,'str'):
        print(TestAttribute(familyname, 'str'))
        familyname = input('Enter Student Familyname:')
    Absences = input('Enter Student Absences days:')
    while TestAttribute(Absences,'int'):
        print(TestAttribute(Absences, 'int'))
        Absences = input('Enter Student Absences days:')
    Exam1 = input('Enter Student Exam1 grade:')
    while TestAttribute(Exam1,'int'):
        print(TestAttribute(Exam1, 'str'))
        Exam1 = input('Enter Student Exam1 grade:')
    Exam2 = input('Enter Student Exam2 grade:')
    while TestAttribute(Exam2,'int'):
        print(TestAttribute(Exam2, 'int'))
        Exam2 = input('Enter Student Exam2 grade:')
    c.addStudent(ID,firstname,familyname,Absences,Exam1,Exam2)
    print('Student added !')

def main_menu(c,filename):
    print('Main Menu'.center(20))
    fn_no = input('''1- Adding Students to the class
2- Removing students from the class
3- Modifying student information
4- Show all students
5- Show top 10 students
6- Show students with largest absences
7- Terminate a program
    ''')
    
    if int(fn_no) in range(1, 8):
        if fn_no == '1':
            add_new_student(c)
            main_menu(c,filename)
        elif fn_no=='2':
            del_by = input('''a. By ID
b. By Student Name
    ''')
            if del_by == 'a':
                ID=input('Enter ID of the Student you wish to remove,')
                student=c.getStudentByID(ID)
                c.delStudent(student)
                print("Student removed!")
                main_menu(c,filename)
                
            elif del_by == 'b':
                Name=input('Enter FirstName of the Student you wish to remove,')
                students=c.getStudentByName(Name)
                if students:
                    print("Records found under name ("+Name+')\n')
                else:
                    print("No student with this name found!")
                    main_menu(c,filename)
                for idx,student in enumerate(students):
                    print(str(idx) +': ')
                    student.PrintStudent() 
                index=input('Please select which record to remove:')
                c.delStudent(students[int(index)])
                print("Student removed!")
                main_menu(c,filename)
            else:
                print("input not recognised. please try again...")
                main_menu(c,filename)

        elif fn_no == '3':
            ID = input('a. Retrieve information by ID:')
            student=c.getStudentByID(ID)
            print("Choose what to edit ")
            select = input('''a. ID
b. NAME
c. Absences
d. Exam1
e. Exam2
''')
            if select == 'a':
                newID = input('Please enter the new ID:')
                while TestAttribute(newID,'int'):
                    print(TestAttribute(newID, 'int'))
                    newID = input('Please enter the new ID:')
                c.modifyStudentID(student,newID)
                print("Student Edited!")
                main_menu(c,filename)

            elif select == 'b':
                newname = input('Please enter the new Name:')
                while TestAttribute(newname,'str'):
                    print(TestAttribute(newname, 'str'))
                    newname = input('Please enter the new Name:')
                c.modifyStudentName(student,newname)
                print("Student Edited!")
                main_menu(c,filename)
            elif select == 'c':
                newAbesences = input('Please enter the new Absence days:')
                while TestAttribute(newAbesences,'int'):
                    print(TestAttribute(newAbesences, 'int'))
                    newAbesences = input('Please enter the new Absence days:')
                c.modifyStudentAbsence(student,newAbesences)
                print("Student Edited!")
                main_menu(c,filename)
            elif select == 'd':
                newExam1 = input('Please enter the new grade for Exam1:')
                while TestAttribute(newExam1,'int'):
                    print(TestAttribute(newExam1, 'int'))
                    newExam1 = input('Please enter the new grade for Exam1:')
                c.modifyStudentExam1(student,newExam1)
                print("Student Edited!")
                main_menu(c,filename)
            elif select == 'e':
                newExam2 = input('Please enter the new Grade for Exam2:')
                while TestAttribute(newExam2,'int'):
                    print(TestAttribute(newExam2, 'int'))
                    newExam2 = input('Please enter the new Grade for Exam2:')
                c.modifyStudentExam2(student,newExam2)
                print("Student Edited!")
                main_menu(c,filename)
            else:
                print("input not recognised. please try again...")
                main_menu(c,filename)
        elif fn_no == '4':
            select = input('''a. Sort by ID
b. Sort by Name
c. Sort by Total Marks
d. Sort by Absences
''')
            if select == 'a':
                students=c.ShowByID()
                for student in students:
                    print(student._ID+': ')
                    student.PrintStudent()
                main_menu(c,filename)
            elif select == 'b':
                students=c.ShowByName()
                for student in students:
                    print(student._ID+': ')
                    student.PrintStudent()
                main_menu(c,filename)
            elif select == 'c':
                students=c.ShowByTotal()
                for student in students:
                    print(student._ID+': ')
                    student.PrintStudent()
                main_menu(c,filename)
            elif select == 'd':
                students=c.ShowByAbsences()
                for student in students:
                    print(student._ID+': ')
                    student.PrintStudent()
                main_menu(c,filename)
            else:
                print("input not recognised. please try again...")
                main_menu(c,filename)
        elif fn_no == '5':
            students=c.ShowByTotal()
            print("The top 10 Students: \n")
            for student in students[:9]:
                print(student._ID+': ')
                student.PrintStudent()
            main_menu(c,filename)
        elif fn_no == '6':
            print("The Student who  has the largest number of absences in the class:\n")
            student=c.GetStudentAbsences()
            print(student._ID+': ')
            student.PrintStudent()
            main_menu(c,filename)
        elif fn_no == '7':
            Save_Quit(c.students,filename)
    else:
        print("input not recognised. please try again...")
        main_menu(c,filename)
        


filename='students.txt'
c=read_data(filename)
main_menu(c,filename)