Devolepment #412

GosudarBBV · 2024-09-16T05:48:30Z

Was added DAO and N-tier architecture and checked in main presentation

mateacademy-ai-mentor

Great job on following the Java conventions and implementing the necessary classes and interfaces! 🌟 However, there are a few important improvements to make regarding exception handling and best practices. Please take a look at the comments for details on how to enhance your code. Remember, clear and informative exception messages are crucial for debugging and maintenance, and using PreparedStatement consistently can help prevent SQL injection attacks. Keep up the good work, and with these adjustments, your code will be even better! 💪

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mateacademy-ai-mentor · 2024-09-16T05:48:59Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+    public Book create(Book book) {
+        String sql = "INSERT INTO books (title, price) VALUES (?, ?)";
+        try (Connection connection = ConnectionUtil.getConnection();
+                PreparedStatement statement =
+                        connection.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)) {
+
+            statement.setString(1, book.getTitle());
+            statement.setBigDecimal(2, book.getPrice());
+
+            int affectedRows = statement.executeUpdate();
+            if (affectedRows < 1) {
+                throw new RuntimeException("Expected to insert at least one row "
+                        + ", but inserted 0 rows.");
+            }
+
+            ResultSet generatedKeys = statement.getGeneratedKeys();
+            if (generatedKeys.next()) {
+                Long id = generatedKeys.getObject(1, Long.class);
+                book.setId(id);
+            }
+        } catch (SQLException e) {
+            throw new RuntimeException("can not add new book to DB: " + book, e);
+        }
+        return book;


It's recommended to use informative exception messages. Instead of throwing a generic RuntimeException in the create method, throw a DataProcessingException with a message that includes the book details for better context.

mateacademy-ai-mentor · 2024-09-16T05:48:59Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+        try (Connection connection = ConnectionUtil.getConnection();
+                PreparedStatement statement =
+                        connection.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)) {
+
+            statement.setString(1, book.getTitle());
+            statement.setBigDecimal(2, book.getPrice());
+
+            int affectedRows = statement.executeUpdate();
+            if (affectedRows < 1) {
+                throw new RuntimeException("Expected to insert at least one row "
+                        + ", but inserted 0 rows.");
+            }
+
+            ResultSet generatedKeys = statement.getGeneratedKeys();
+            if (generatedKeys.next()) {
+                Long id = generatedKeys.getObject(1, Long.class);
+                book.setId(id);
+            }


Use PreparedStatement over Statement, even for a static query with no parameters in findAll() method. It's the best practice, and it's slightly faster.

mateacademy-ai-mentor · 2024-09-16T05:48:59Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+        } catch (SQLException e) {
+            throw new RuntimeException("can not add new book to DB: " + book, e);


Use DataProcessingException instead of RuntimeException to maintain consistency across the DAO layer when handling SQL exceptions.

mateacademy-ai-mentor · 2024-09-16T05:48:59Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+    public Optional<Book> findById(Long id) {
+        String sql = "SELECT * FROM books WHERE id = ?";
+        try (Connection connection = ConnectionUtil.getConnection();
+                PreparedStatement statement = connection.prepareStatement(sql)) {
+            statement.setLong(1, id);
+            ResultSet result = statement.executeQuery();
+            if (result.next()) {
+                String title = result.getString("title");
+                BigDecimal price = result.getObject("price", BigDecimal.class);
+                Book book = new Book();
+                book.setId(id);
+                book.setTitle(title);
+                book.setPrice(price);
+                return Optional.of(book);
+            }
+        } catch (SQLException e) {
+            throw new RuntimeException("Cannot create a connection to the DB", e);
+        }
+        return Optional.empty();


Move the logic for retrieving a Book from a ResultSet into a separate private method to avoid code duplication. This applies to the findById method.

mateacademy-ai-mentor · 2024-09-16T05:48:59Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+        } catch (SQLException e) {
+            throw new RuntimeException("Cannot create a connection to the DB", e);


The exception message here is misleading. It should indicate that the retrieval of the book by id failed, not the creation of the connection. Use DataProcessingException with a more informative message, such as 'Can't get a book by id ' + id.

mateacademy-ai-mentor · 2024-09-16T05:48:59Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+    private Book getBookFromResultSet(ResultSet resultSet) throws SQLException {
+        Long id = resultSet.getObject("id", Long.class);
+        String title = resultSet.getString("title");
+        BigDecimal price = resultSet.getObject("price", BigDecimal.class);
+
+        Book book = new Book();
+        book.setId(id);
+        book.setTitle(title);
+        book.setPrice(price);
+        return book;


The method getBookFromResultSet is correctly extracting the book from the result set. However, ensure that the findAll method uses PreparedStatement over Statement as per best practices.

mateacademy-ai-mentor · 2024-09-16T05:49:00Z

src/main/java/mate/academy/model/Book.java

+    public Book(String title, BigDecimal price) {
+        this.title = title;
+        this.price = price;
+    }


When you convert ResultSet to Book, it's better to create an object using setters or constructor but not both of them. Currently, you have a constructor that sets the title and price, but the id is set via a setter. Consider adding an id parameter to the constructor or initializing all fields using setters.

mateacademy-ai-mentor · 2024-09-16T05:49:00Z

src/main/java/mate/academy/model/Book.java

+        return "Car("
+                + "id=" + id
+                + ", title=" + title
+                + ", price=" + price;


There is a typo in the toString method. You're returning a string that starts with "Car(" instead of "Book(". This should be corrected to accurately represent the Book object.

mateacademy-ai-mentor · 2024-09-16T05:49:00Z

src/main/java/mate/academy/service/ConnectionUtil.java

+import java.util.Properties;
+
+public class ConnectionUtil {
+    private static final String DB_URL = "jdbc:mysql://127.0.0.1:3306/test";


The DB_URL is incomplete. It should contain the full JDBC URL to connect to the database. For example, "jdbc:mysql://localhost:3306/myDatabase", where myDatabase is the name of your database.

mateacademy-ai-mentor · 2024-09-16T05:49:00Z

src/main/java/mate/academy/service/ConnectionUtil.java

+        DB_PROPERTIES.put("user","root");
+        DB_PROPERTIES.put("password", "Nero0410");


Storing credentials in the code is a bad practice due to security reasons. It's better to use environment variables or a configuration file that is not included in your version control.

GosudarBBV · 2024-09-22T17:41:54Z

after attemt 1

mateacademy-ai-mentor

Hey there! It looks like you've put in a lot of effort, and you're definitely on the right track. However, I noticed a few critical issues that should be addressed to make sure your code is secure and robust. For instance, hardcoding credentials can be a security risk, and not properly closing database connections could lead to resource leaks. Also, making sure your SQL queries are clear and using PreparedStatement can help prevent SQL injection attacks. Don't worry, you're doing great! Just make these small tweaks, and your code will be even better. Keep up the good work! 👍🔒💻

✨ Please rate this review in the Platform's notification center. I will be grateful for your feedback! ✨

mateacademy-ai-mentor · 2024-09-22T17:42:52Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+                book.setId(id);
+            }
+        } catch (SQLException e) {
+            throw new DataProcessingException("can not add new book to DB: " + book);


Use a more informative message for the exception that includes the book's details. For example: 'Can't save a book ' + book

mateacademy-ai-mentor · 2024-09-22T17:42:52Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+                return Optional.of(getBookFromResultSet(resultSet));
+            }
+        } catch (SQLException e) {
+            throw new RuntimeException("Cannot create a connection to the DB", e);


The exception message should be more specific. It's better to use 'Can't get a book by id ' + id instead of a generic 'Cannot create a connection to the DB'.

mateacademy-ai-mentor · 2024-09-22T17:42:52Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+                        + book.getId());
+            }
+        } catch (SQLException e) {
+            throw new DataProcessingException("Can't create a connection to the DB");


The exception message 'Can't create a connection to the DB' is misleading here. It should be more informative and specific to the operation being performed, like 'Can't update the book with id: ' + book.getId().

mateacademy-ai-mentor · 2024-09-22T17:42:52Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+    public List<Book> findAll() {
+        List<Book> books = new ArrayList<>();
+        String sql = "SELECT * FROM books";
+        try (Connection connection = ConnectionUtil.getConnection();


Use PreparedStatement over Statement, even for a static query with no parameters in findAll() method. It's the best practice, and it's slightly faster.

mateacademy-ai-mentor · 2024-09-22T17:42:53Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+            return statement.executeUpdate() > 0;
+        } catch (SQLException e) {
+            throw new DataProcessingException("Can't delete the book with id: "
+                    + id);


The exception message should be more informative. For example, 'Can't delete the book with id: ' + id.

mateacademy-ai-mentor · 2024-09-22T17:42:53Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+
+    @Override
+    public boolean deleteById(Long id) {
+        String sql = "DELETE FROM books WHERE id = ?";


Use uppercase for SQL keywords in your queries. For example, use 'DELETE FROM' instead of 'delete from'.

mateacademy-ai-mentor · 2024-09-22T17:42:53Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+        }
+    }
+
+    private Book getBookFromResultSet(ResultSet resultSet) throws SQLException {


Consider moving the logic for retrieving data from the ResultSet into a separate private method to avoid code duplication.

mateacademy-ai-mentor · 2024-09-22T17:42:53Z

src/main/java/mate/academy/service/ConnectionUtil.java

+import java.util.Properties;
+
+public class ConnectionUtil {
+    private static final String DB_URL = "jdbc:mysql://127.0.0.1:3306/test";


The DB_URL is incomplete. It should specify the database server's URL, the port, and the database name you want to connect to.

mateacademy-ai-mentor · 2024-09-22T17:42:53Z

src/main/java/mate/academy/service/ConnectionUtil.java

+        String userName = "root";
+        String password = "Nero0410";


Hardcoding credentials in the source code is a security risk. Consider using environment variables or a configuration file to store sensitive information securely.

mateacademy-ai-mentor · 2024-09-22T17:42:53Z

src/main/java/mate/academy/service/ConnectionUtil.java

+    }
+
+    public static Connection getConnection() throws SQLException {
+        return DriverManager.getConnection(DB_URL,DB_PROPERTIES);


The getConnection method should use try-with-resources or ensure that the Connection is closed properly elsewhere in the code to prevent potential resource leaks.

GosudarBBV · 2024-09-22T18:03:47Z

Attempt 2

mateacademy-ai-mentor

Great job on implementing the main class and handling CRUD operations via the BookDao interface! 🌟 Your use of BigDecimal for monetary values is spot on. Just remember to handle exceptions gracefully, secure sensitive information like database passwords, and refine your use of constructors and setters. Keep up the good work, and remember that addressing the feedback will help you write even more robust and secure code! 👍🚀

✨ Please rate this review in the Platform's notification center. I will be grateful for your feedback! ✨

mateacademy-ai-mentor · 2024-09-22T18:05:23Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+        try (Connection connection = ConnectionUtil.getConnection();
+                PreparedStatement statement =
+                        connection.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)) {


Use PreparedStatement over Statement, even for a static query with no parameters in findAll() method. It's the best practice, and it's slightly faster. However, in this case, you are already using PreparedStatement, so just ensure you do so consistently across all methods.

mateacademy-ai-mentor · 2024-09-22T18:05:23Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+                PreparedStatement statement =
+                        connection.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)) {
+
+            statement.setString(1, book.getTitle());


Remember to avoid code duplication. Since you're setting parameters for PreparedStatement in multiple methods (create, update, etc.), consider creating a private method to handle this.

mateacademy-ai-mentor · 2024-09-22T18:05:23Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+                Long id = generatedKeys.getObject(1, Long.class);
+                book.setId(id);
+            }
+        } catch (SQLException e) {


Use informative messages for exceptions. Instead of a generic message, include the book's details for better debugging. For example: "Can't save a book: " + book

mateacademy-ai-mentor · 2024-09-22T18:05:24Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+                return Optional.of(getBookFromResultSet(resultSet));
+            }
+        } catch (SQLException e) {
+            throw new RuntimeException("Can't get a book by id" + id, e);


Use informative messages for exceptions. Include the book's ID for better debugging. For example: "Can't get a book by id: " + id

mateacademy-ai-mentor · 2024-09-22T18:05:24Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+                books.add(getBookFromResultSet(resultSet));
+            }
+        } catch (SQLException e) {
+            throw new DataProcessingException("Can't get all books from the database");


Use informative messages for exceptions. Include more details if possible for better debugging.

mateacademy-ai-mentor · 2024-09-22T18:05:24Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+            return statement.executeUpdate() > 0;
+        } catch (SQLException e) {
+            throw new DataProcessingException("Can't delete the book with id: "
+                    + id);


Use informative messages for exceptions. Include the book's ID for better debugging. For example: "Can't delete the book with id: " + id

mateacademy-ai-mentor · 2024-09-22T18:05:24Z

src/main/java/mate/academy/dao/BookDaoImpl.java

+        }
+    }
+
+    private Book getBookFromResultSet(ResultSet resultSet) throws SQLException {


When converting ResultSet to Book, choose either setters or constructor for object creation, but not both. Since you are using setters here, consider creating a constructor in Book class that takes id, title, and price as parameters and use it here.

mateacademy-ai-mentor · 2024-09-22T18:05:24Z

src/main/java/mate/academy/service/ConnectionUtil.java

+import java.util.Properties;
+
+public class ConnectionUtil {
+    private static final String DB_URL = "jdbc:mysql://127.0.0.1:3306/test?user=root";


The DB_URL is incomplete. It should include the JDBC URL specifying the database to connect to, for example 'jdbc:mysql://localhost:3306/yourDatabaseName'.

mateacademy-ai-mentor · 2024-09-22T18:05:24Z

src/main/java/mate/academy/service/ConnectionUtil.java

+    private static final String DB_URL = "jdbc:mysql://127.0.0.1:3306/test?user=root";
+    private static final Properties DB_PROPERTIES;
+    private static final String USERNAME = "root";
+    private static final String PASSWORD = "Nero0410";


Storing the password in the source code is a security risk. Consider using environment variables or a configuration file that is not included in the version control system.

mateacademy-ai-mentor · 2024-09-22T18:05:24Z

src/main/java/mate/academy/service/ConnectionUtil.java

+        }
+    }
+
+    public static Connection getConnection() throws SQLException {


It's good practice to use try-with-resources or closing the connection explicitly in the calling code to prevent potential resource leaks. Ensure that connections are closed properly after use.

)

GosudarBBV · 2024-09-22T18:22:44Z

Attempt 3

Elena-Bruyako

one comment

Elena-Bruyako · 2024-09-22T18:29:59Z

src/main/resources/init_db.sql

@@ -0,0 +1,5 @@
+CREATE TABLE books (
+    id BIGINT NOT NULL AUTO_INCREMENT,


Suggested change

id BIGINT NOT NULL AUTO_INCREMENT,

id BIGINT AUTO_INCREMENT,

liliia-ponomarenko

Great! 🔥

GosudarBBV added 2 commits September 16, 2024 08:35

Implemented DAO and N-tier architecture

1680052

Implemented DAO and N-tier architecture

180f166

mateacademy-ai-mentor suggested changes Sep 16, 2024

View reviewed changes

GosudarBBV added 2 commits September 16, 2024 08:56

Implemented DAO and N-tier architecture

df391fe

Fixed according to AI-mentor

688c379

GosudarBBV requested a review from mateacademy-ai-mentor September 22, 2024 17:42

mateacademy-ai-mentor suggested changes Sep 22, 2024

View reviewed changes

Fixed according to AI-mentor (attempt 2)

8e06965

GosudarBBV requested a review from mateacademy-ai-mentor September 22, 2024 18:05

mateacademy-ai-mentor approved these changes Sep 22, 2024

View reviewed changes

GosudarBBV added 2 commits September 22, 2024 21:19

Fixed according to AI-mentor (attempt 3

761d644

)

Fixed according to AI-mentor (attempt 3)

8708c72

GosudarBBV requested a review from mateacademy-ai-mentor September 22, 2024 18:21

Elena-Bruyako suggested changes Sep 22, 2024

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GosudarBBV added 2 commits September 22, 2024 21:36

Fixed according to AI-mentor (attempt 4)

0380514

Fixed according to mentor (attempt 4)

427fe7b

GosudarBBV requested a review from Elena-Bruyako September 22, 2024 18:38

liliia-ponomarenko approved these changes Sep 23, 2024

View reviewed changes

		} catch (SQLException e) {
		throw new RuntimeException("can not add new book to DB: " + book, e);

		} catch (SQLException e) {
		throw new RuntimeException("Cannot create a connection to the DB", e);

		DB_PROPERTIES.put("user","root");
		DB_PROPERTIES.put("password", "Nero0410");

		@@ -0,0 +1,5 @@
		CREATE TABLE books (
		id BIGINT NOT NULL AUTO_INCREMENT,

Devolepment #412

Are you sure you want to change the base?

Devolepment #412

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GosudarBBV commented Sep 16, 2024

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GosudarBBV commented Sep 22, 2024 • edited Loading

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GosudarBBV commented Sep 22, 2024

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GosudarBBV commented Sep 22, 2024

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GosudarBBV commented Sep 22, 2024 •

edited

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