How to pass user inputs to an object of a class?-CodePudding

This code is a Simple Student Management System in which I want it to receive inputs from the user and display according to the call. I have created a class Student and initialized the variables. I created a method accept(self) for receiving the user inputs and appending the details to a list of dictionaries. But I am stuck on how I can initialize the inputs that I have received. How can I call the methods outside of class Student since I am unable to create an object for class Student? I am a beginner in Python. Having a hard time understanding OOP. Please help me! Here is the code I wrote:

class Student:
    student_details = []
    def __init__(self, name, rollno, mark1, mark2):
        self.name = name
        self.rollno = rollno
        self.mark1 = mark1
        self.mark2 = mark2

    def accept(self):
        no_of_entries = int(input("Enter the number of entries: "))
        i = 1
        while i <= no_of_entries:
            print(f"Student {i}")
            name = input("Name: ")
            rollno = int(input("Roll: "))
            mark1 = int(input("Mark 1: "))
            mark2 = int(input("Mark 2: "))
            Student(name, rollno, mark1, mark2).student_details.append({
                "Name": self.name,
                "Rollno": self.rollno,
                "Mark1": self.mark1,
                "Mark2": self.mark2,
            })
            print()
            i  = 1
        print(Student.student_details)

student1 = Student()

proceed = True
while proceed:
    print("STUDENT MANAGEMENT SYSTEM".center(50, '-'))
    print()
    print("* Accept Student entries (1): ")
    print("* Search Student entries (2): ")
    print("* Update Student entries (3): ")
    print("* Delete Student entries (4): ")
    print("* Display Student entries (5): ")
    choice = int(input("Enter your choice: "))
    if choice == 1:

I get the error:

Student.__init__() missing 4 required positional arguments: 'name', 'rollno', 'mark1', and 'mark2'

I don't know what to do. Even this is the problem I am facing with OOP in Python. If anyone can help me with this than I will be grateful

CodePudding user response：

EDIT: The callback comes from the student1 = Student() delete the statement and declare the accept method as a static method. Then you can deklare a student in the method and can appent the student.

Your mistake should be here:

 Student(name, rollno, mark1, mark2).student_details.append({
                "Name": self.name,
                "Rollno": self.rollno,
                "Mark1": self.mark1,
                "Mark2": self.mark2,
            })

You try to initialise a object and then you try to use it as a dict.

st1 = Student(name, rollno, mark1, mark2)
Student.student_details.append(st1)

Also you can use a classattribut in a object but the changes will only be present in the object. It wouldnt be in all object.

It would be best make the method accept in a function or you will end up with many object with the same values. If you want to leave it as a method you can change the code to:

Student.student_details.append(self)

CodePudding user response：

By default methods defined in a Python class are instance methods, so they need to be called on an already-existing object instance. If you want to create a custom constructor, the method should be probably marked as a class method by using @classmethod decorator, so it can be called on the class itself.

class Student:
    student_details = []
    def __init__(self, name, rollno, mark1, mark2):
        self.name = name
        self.rollno = rollno
        self.mark1 = mark1
        self.mark2 = mark2
    @classmethod
    def accept(cls):
        no_of_entries = int(input("Enter the number of entries: "))
        for i in range(no_of_entries):
            print(f"Student {i}")
            name = input("Name: ")
            rollno = int(input("Roll: "))
            mark1 = int(input("Mark 1: "))
            mark2 = int(input("Mark 2: "))
            student = cls(name, rollno, mark1, mark2)
            cls.student_details.append(student)
        print(cls.student_details)

Student.accept()

CodePudding user response：

student1 = Student()

you need to pass 4 parameters here

def __init__(self, name, rollno, mark1, mark2):

So you should have

student1 = Student('name', 'rollno', 'mark1', 'mark2')

or something

CodePudding user response：

You forgot to put arguments when you call that class. For example:

student1 = Student(name='a', rollno='0', mark1='1', mark2='2')

I'm not sure what your objective is. If you just want to input student information into a list, maybe the code below can give you an idea.

class Student:
student_details = []
def __init__(self, name, rollno, mark1, mark2):
    self.name = name
    self.rollno = rollno
    self.mark1 = mark1
    self.mark2 = mark2


student_list = []

print("STUDENT MANAGEMENT SYSTEM".center(50, '-'))
print()
print("* Accept Student entries (1): ")
print("* Search Student entries (2): ")
print("* Update Student entries (3): ")
print("* Delete Student entries (4): ")
print("* Display Student entries (5): ")
choice = int(input("Enter your choice: "))
if choice == 1:
    print("You have selected (1) - Accept Student entries")
    no_of_entries = int(input("Enter the number of entries: "))
    for i in range(0, no_of_entries): 
        print("Input student no", i 1, "information.")
        student = Student(name=input("Name: "), rollno=input("Roll: "), mark1=input("Mark 1: "), mark2=input("Mark 2: "))
        student_list.append(student)
elif choice == 2:
    pass
elif choice == 3:
    pass
elif choice == 4:
    pass
elif choice == 5:
    pass
else:
    print("Invalid choice.")