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Implementing Book Checkout and Return Features for PyQt5 Library Management Systems

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Checkout Workflow Validation Rules

All checkout operations follow the below validation sequence to ensure data consistency:

  • When a user inputs a book ID, the system automatically queries the book database and populates book metadata (title, author, category, publisher, publish date) if a matching record exists
  • Empty or invalid book IDs trigger a warning alert and block further operation
  • Users are restricted to a maximum of 5 active checked-out books; exceeding this limit blocks checkout
  • Duplicate checkout of the same book (with an active unreturned record) is not allowed
  • Successful checkout triggers three database operations: increment the user's borrowed book count, update the book's borrow count and reduce availible stock, and insert a new checkout record to the user-book relation table
  • A success notification is displayed after all database operations complete successfully
import sys
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *
import qdarkstyle
import time
from PyQt5.QtSql import *
from db.userInfoManager import UserBookManager
from db.userInfoManager import BookDbManager
from db.userInfoManager import UserDbManager
import assets.icons

class BookCheckoutDialog(QDialog):
    checkout_success = pyqtSignal()

    def __init__(self, patron_id, parent=None):
        super().__init__(parent)
        self.patron_id = patron_id
        self.init_ui()
        self.setWindowModality(Qt.WindowModal)
        self.setWindowTitle("Book Checkout")
        self.user_book_ops = UserBookManager()
        self.book_ops = BookDbManager()
        self.user_ops = UserDbManager()

    def init_ui(self):
        BOOK_CATEGORIES = ["Philosophy", "Social Science", "Politics", "Law", "Military", 
                        "Economics", "Culture", "Education", "Sports", "Linguistics",
                         "Art", "History", "Geography", "Astronomy", "Biology", 
                         "Healthcare", "Agriculture"]
        self.resize(320, 420)
        self.form_layout = QFormLayout()
        self.setLayout(self.form_layout)

        self.patron_label = QLabel("Patron ID:")
        self.patron_id_display = QLabel(self.patron_id)
        self.header_label = QLabel("  Book Checkout")
        self.title_label = QLabel("Book Title:")
        self.book_id_label = QLabel("Book ID:")
        self.author_label = QLabel("Author:")
        self.category_label = QLabel("Category:")
        self.publisher_label = QLabel("Publisher:")
        self.pub_date_label = QLabel("Publish Date:")

        self.submit_checkout_btn = QPushButton("Confirm Checkout")

        self.title_input = QLineEdit()
        self.book_id_input = QLineEdit()
        self.author_input = QLineEdit()
        self.category_dropdown = QComboBox()
        self.category_dropdown.addItems(BOOK_CATEGORIES)
        self.publisher_input = QLineEdit()
        self.pub_date_input = QLineEdit()

        self.title_input.setMaxLength(30)
        self.book_id_input.setMaxLength(10)
        self.author_input.setMaxLength(20)
        self.publisher_input.setMaxLength(25)

        self.form_layout.addRow("", self.header_label)
        self.form_layout.addRow(self.patron_label, self.patron_id_display)
        self.form_layout.addRow(self.title_label, self.title_input)
        self.form_layout.addRow(self.book_id_label, self.book_id_input)
        self.form_layout.addRow(self.author_label, self.author_input)
        self.form_layout.addRow(self.category_label, self.category_dropdown)
        self.form_layout.addRow(self.publisher_label, self.publisher_input)
        self.form_layout.addRow(self.pub_date_label, self.pub_date_input)
        self.form_layout.addRow("", self.submit_checkout_btn)

        font = QFont()
        font.setPixelSize(22)
        self.header_label.setFont(font)
        font.setPixelSize(16)
        self.patron_id_display.setFont(font)
        font.setPixelSize(14)
        for field_label in [self.patron_label, self.title_label, self.book_id_label, self.author_label, self.category_label, self.publisher_label, self.pub_date_label]:
            field_label.setFont(font)

        for readonly_field in [self.title_input, self.author_input, self.publisher_input, self.pub_date_input]:
            readonly_field.setFont(font)
            readonly_field.setReadOnly(True)
            readonly_field.setStyleSheet("background-color: #2d2d2d; color: #ffffff;")
        self.book_id_input.setFont(font)
        self.category_dropdown.setFont(font)
        self.category_dropdown.setStyleSheet("background-color: #2d2d2d; color: #ffffff;")

        font.setPixelSize(16)
        self.submit_checkout_btn.setFont(font)
        self.submit_checkout_btn.setFixedSize(150, 36)

        self.header_label.setMargin(10)
        self.form_layout.setVerticalSpacing(12)

        self.submit_checkout_btn.clicked.connect(self.handle_checkout_submit)
        self.book_id_input.textChanged.connect(self.handle_book_id_change)
        self.book_id_input.returnPressed.connect(self.handle_checkout_submit)

    def handle_checkout_submit(self):
        book_id = self.book_id_input.text().strip()
        if not book_id:
            QMessageBox.warning(self, "Warning", "Please enter a valid book ID", QMessageBox.Yes)
            return
        
        book_data = self.book_ops.querybyBookID(book_id)
        if not book_data:
            QMessageBox.warning(self, "Warning", "No matching book found for the entered ID", QMessageBox.Yes)
            return
        
        active_checkouts = self.user_book_ops.countBorrowNum(self.patron_id)
        current_checkout_count = active_checkouts[0][0] if active_checkouts else 0
        if current_checkout_count >= 5:
            QMessageBox.warning(self, "Warning", "You have reached the maximum limit of 5 checked out books", QMessageBox.Yes)
            return
        
        existing_checkout = self.user_book_ops.borrowStatus(self.patron_id, book_id)
        if existing_checkout[0][0] > 0:
            QMessageBox.warning(self, "Warning", "You have already checked out this book and not returned it yet", QMessageBox.Yes)
            return
        
        self.user_ops.borrowOrReturnBook(self.patron_id, borrow=1)
        self.book_ops.borrowOrReturnBook(book_id, borrowflag=1)
        checkout_date = time.strftime('%Y-%m-%d', time.localtime())
        self.user_book_ops.borrowOrReturnBook(self.patron_id, book_id, checkout_date, borrowflag=1)

        QMessageBox.information(self, "Success", "Book checked out successfully!", QMessageBox.Yes)
        self.checkout_success.emit()
        self.close()

    def handle_book_id_change(self):
        book_id = self.book_id_input.text().strip()
        if not book_id:
            self.title_input.clear()
            self.author_input.clear()
            self.publisher_input.clear()
            self.pub_date_input.clear()
            return
        
        book_data = self.book_ops.querybyBookID(book_id)
        if book_data:
            self.title_input.setText(book_data[0][0])
            self.author_input.setText(book_data[0][2])
            self.category_dropdown.setCurrentText(book_data[0][3])
            self.publisher_input.setText(book_data[0][4])
            self.pub_date_input.setText(book_data[0][5])

if __name__ == "__main__":
    app = QApplication(sys.argv)
    app.setWindowIcon(QIcon(":/icons/app_icon.png"))
    app.setStyleSheet(qdarkstyle.load_stylesheet_pyqt5())
    checkout_window = BookCheckoutDialog("test_user_001")
    checkout_window.show()
    sys.exit(app.exec_())

Return Workflow Validation Rules

Return operations follow the below validation logic:

  • Empty book ID input triggers a input validation warning
  • If no active unreturned checkout record exists for the input book ID under the current user, a notification is displayed indicating no return is required
  • Successful return triggers three database operations: decrement the user's active borrowed count, increment the book's available stock, and update the corresponding user-book record with the return date to mark it as completed
  • A success notification is displayed after all operations complete
import sys
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *
import qdarkstyle
import time
from PyQt5.QtSql import *
from db.userInfoManager import UserBookManager
from db.userInfoManager import BookDbManager
from db.userInfoManager import UserDbManager
import assets.icons

class BookReturnDialog(QDialog):
    return_success = pyqtSignal()

    def __init__(self, patron_id, parent=None):
        super().__init__(parent)
        self.patron_id = patron_id
        self.init_ui()
        self.setWindowModality(Qt.WindowModal)
        self.setWindowTitle("Book Return")
        self.user_book_ops = UserBookManager()
        self.book_ops = BookDbManager()
        self.user_ops = UserDbManager()

    def init_ui(self):
        BOOK_CATEGORIES = ["Philosophy", "Social Science", "Politics", "Law", "Military", 
                        "Economics", "Culture", "Education", "Sports", "Linguistics",
                         "Art", "History", "Geography", "Astronomy", "Biology", 
                         "Healthcare", "Agriculture"]
        self.resize(320, 420)
        self.form_layout = QFormLayout()
        self.setLayout(self.form_layout)

        self.patron_label = QLabel("Patron ID:")
        self.patron_id_display = QLabel(self.patron_id)
        self.header_label = QLabel("  Book Return")
        self.title_label = QLabel("Book Title:")
        self.book_id_label = QLabel("Book ID:")
        self.author_label = QLabel("Author:")
        self.category_label = QLabel("Category:")
        self.publisher_label = QLabel("Publisher:")
        self.pub_date_label = QLabel("Publish Date:")

        self.submit_return_btn = QPushButton("Confirm Return")

        self.title_input = QLineEdit()
        self.book_id_input = QLineEdit()
        self.author_input = QLineEdit()
        self.category_dropdown = QComboBox()
        self.category_dropdown.addItems(BOOK_CATEGORIES)
        self.publisher_input = QLineEdit()
        self.pub_date_input = QLineEdit()

        self.title_input.setMaxLength(30)
        self.book_id_input.setMaxLength(10)
        self.author_input.setMaxLength(20)
        self.publisher_input.setMaxLength(25)

        self.form_layout.addRow("", self.header_label)
        self.form_layout.addRow(self.patron_label, self.patron_id_display)
        self.form_layout.addRow(self.title_label, self.title_input)
        self.form_layout.addRow(self.book_id_label, self.book_id_input)
        self.form_layout.addRow(self.author_label, self.author_input)
        self.form_layout.addRow(self.category_label, self.category_dropdown)
        self.form_layout.addRow(self.publisher_label, self.publisher_input)
        self.form_layout.addRow(self.pub_date_label, self.pub_date_input)
        self.form_layout.addRow("", self.submit_return_btn)

        font = QFont()
        font.setPixelSize(22)
        self.header_label.setFont(font)
        font.setPixelSize(16)
        self.patron_id_display.setFont(font)
        font.setPixelSize(14)
        for field_label in [self.patron_label, self.title_label, self.book_id_label, self.author_label, self.category_label, self.publisher_label, self.pub_date_label]:
            field_label.setFont(font)

        for readonly_field in [self.title_input, self.author_input, self.publisher_input, self.pub_date_input, self.category_dropdown]:
            readonly_field.setFont(font)
            readonly_field.setReadOnly(True) if hasattr(readonly_field, 'setReadOnly') else None
            readonly_field.setStyleSheet("background-color: #2d2d2d; color: #ffffff;")
        self.book_id_input.setFont(font)

        font.setPixelSize(16)
        self.submit_return_btn.setFont(font)
        self.submit_return_btn.setFixedSize(150, 36)

        self.header_label.setMargin(10)
        self.form_layout.setVerticalSpacing(12)

        self.submit_return_btn.clicked.connect(self.handle_return_submit)
        self.book_id_input.textChanged.connect(self.handle_book_id_change)

    def handle_return_submit(self):
        book_id = self.book_id_input.text().strip()
        if not book_id:
            QMessageBox.warning(self, "Warning", "Please enter a valid book ID", QMessageBox.Yes)
            return
        
        active_checkout = self.user_book_ops.borrowStatus(self.patron_id, book_id)
        if active_checkout[0][0] == 0:
            QMessageBox.information(self, "Notification", "You have not checked out this book, no return required", QMessageBox.Yes)
            return
        
        self.user_ops.borrowOrReturnBook(self.patron_id, borrow=0)
        self.book_ops.borrowOrReturnBook(book_id, borrowflag=0)
        return_date = time.strftime('%Y-%m-%d', time.localtime())
        self.user_book_ops.borrowOrReturnBook(self.patron_id, book_id, return_date, borrowflag=0)

        QMessageBox.information(self, "Success", "Book returned successfully!", QMessageBox.Yes)
        self.return_success.emit()
        self.close()

    def handle_book_id_change(self):
        book_id = self.book_id_input.text().strip()
        if not book_id:
            self.title_input.clear()
            self.author_input.clear()
            self.publisher_input.clear()
            self.pub_date_input.clear()
            return
        
        active_checkout = self.user_book_ops.borrowStatus(self.patron_id, book_id)
        if active_checkout[0][0] > 0:
            book_data = self.book_ops.querybyBookID(book_id)
            if book_data:
                self.title_input.setText(book_data[0][0])
                self.author_input.setText(book_data[0][2])
                self.category_dropdown.setCurrentText(book_data[0][3])
                self.publisher_input.setText(book_data[0][4])
                self.pub_date_input.setText(book_data[0][5])

if __name__ == "__main__":
    app = QApplication(sys.argv)
    app.setWindowIcon(QIcon(":/icons/app_icon.png"))
    app.setStyleSheet(qdarkstyle.load_stylesheet_pyqt5())
    return_window = BookReturnDialog("test_user_001")
    return_window.show()
    sys.exit(app.exec_())
Tags: pyqt5PythonLibrary Management SystemGUI Development
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