students.go

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"
)

type StudentInfo struct {
	ID        string
	FirstName string
	LastName  string
	Grade     int
}

type StudentManagement struct {
	Students map[string]StudentInfo
}

// File to save and load student data
const dataFile = "students.json"

// AddStudent adds a new student to the student list.
func (sm *StudentManagement) AddStudent(student StudentInfo) {
	sm.Students[student.ID] = student
	fmt.Printf("Student with ID %s added successfully.\n", student.ID)
	sm.SaveToFile()
}

// UpdateStudent updates an existing student's information.
func (sm *StudentManagement) UpdateStudent(student StudentInfo) {
	if _, exists := sm.Students[student.ID]; exists {
		sm.Students[student.ID] = student
		fmt.Printf("Student with ID %s updated successfully.\n", student.ID)
		sm.SaveToFile()
	} else {
		fmt.Printf("Student with ID %s does not exist.\n", student.ID)
	}
}

// DeleteStudent removes a student from the student list by ID.
func (sm *StudentManagement) DeleteStudent(id string) {
	if _, exists := sm.Students[id]; exists {
		delete(sm.Students, id)
		fmt.Printf("Student with ID %s deleted successfully.\n", id)
		sm.SaveToFile()
	} else {
		fmt.Printf("Student with ID %s does not exist.\n", id)
	}
}

// GetStudent retrieves a student's information by ID.
func (sm *StudentManagement) GetStudent(id string) {
	if student, exists := sm.Students[id]; exists {
		fmt.Printf("Student Info - ID: %s, Name: %s %s, Grade: %d\n", student.ID, student.FirstName, student.LastName, student.Grade)
	} else {
		fmt.Printf("Student with ID %s not found.\n", id)
	}
}

// ListStudents prints the details of all students.
func (sm *StudentManagement) ListStudents() {
	if len(sm.Students) == 0 {
		fmt.Println("No students found.")
		return
	}

	for _, student := range sm.Students {
		fmt.Printf("ID: %s, Name: %s %s, Grade: %d\n", student.ID, student.FirstName, student.LastName, student.Grade)
	}
}

// SaveToFile saves the student management data to a JSON file.
func (sm *StudentManagement) SaveToFile() {
	data, err := json.MarshalIndent(sm, "", "  ")
	if err != nil {
		fmt.Println("Error saving data:", err)
		return
	}
	err = ioutil.WriteFile(dataFile, data, 0644)
	if err != nil {
		fmt.Println("Error writing to file:", err)
	}
}

// LoadFromFile loads the student management data from a JSON file.
func (sm *StudentManagement) LoadFromFile() {
	if _, err := os.Stat(dataFile); os.IsNotExist(err) {
		// File doesn't exist, nothing to load
		return
	}

	data, err := ioutil.ReadFile(dataFile)
	if err != nil {
		fmt.Println("Error reading file:", err)
		return
	}

	err = json.Unmarshal(data, sm)
	if err != nil {
		fmt.Println("Error parsing JSON:", err)
	}
}