Implemented BookDao #416
Implemented BookDao #416
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Great job on following the Java interface naming conventions in your BookDao interface and structuring your Book class according to JavaBean conventions! Just remember to keep an eye on the consistency of object creation and exception messages for future enhancements. Keep up the good work! 👍💡
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| BookDao bookDao = (BookDao) injector.getInstance(BookDao.class); | ||
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| Book zapovit = new Book("zapovit", BigDecimal.valueOf(100)); | ||
| Book newZapiovit = bookDao.create(zapovit); |
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The variable 'newZapiovit' is never used. If you don't need the result of 'bookDao.create(zapovit)', you can omit assigning it to a variable.
| Book zapovit = new Book("zapovit", BigDecimal.valueOf(100)); | ||
| Book newZapiovit = bookDao.create(zapovit); | ||
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| Optional<Book> bookById2 = bookDao.findById(2L); |
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The variable 'bookById2' is never used. Make sure to use it or remove it if it's not necessary for the main logic.
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| Optional<Book> bookById2 = bookDao.findById(2L); | ||
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| List<Book> allBooks = bookDao.findAll(); |
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The variable 'allBooks' is never used. Make sure to use it or remove it if it's not necessary for the main logic.
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| List<Book> allBooks = bookDao.findAll(); | ||
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| Book updateZapovit = bookDao.update(zapovit); |
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The variable 'updateZapovit' is never used. If you don't need the result of 'bookDao.update(zapovit)', you can omit assigning it to a variable.
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| boolean isDeleted = bookDao.deleteById(3L); |
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The variable 'isDeleted' is never used. Consider logging the result or handling the deletion result in some way.
| throw new DataProcessingException( | ||
| "Expected to update at least one row, but updated 0 rows."); |
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Use DataProcessingException for consistency with the rest of the DAO layer.
| } | ||
| return book; | ||
| } catch (SQLException e) { | ||
| throw new DataProcessingException("Can not create a connection to the database", e); |
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The exception message should be more informative and specific to the operation being performed. For example: 'Can't update book: ' + book
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| @Override | ||
| public boolean deleteById(Long id) { | ||
| String sql = "DELETE FROM books WHERE id = ?;"; |
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Use uppercase for SQL keywords.
| PreparedStatement statement = connection.prepareStatement(sql)) { | ||
| statement.setLong(1, id); | ||
| int affectedRows = statement.executeUpdate(); | ||
| return affectedRows >= 1; |
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The deleteById method should return true only if one or more rows were affected. The current implementation is correct, so no action is needed here.
| int affectedRows = statement.executeUpdate(); | ||
| return affectedRows >= 1; | ||
| } catch (SQLException e) { | ||
| throw new DataProcessingException("Can not create a connection to the database", e); |
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The exception message should be more informative and specific to the operation being performed. For example: 'Can't delete book with id: ' + id
| @@ -0,0 +1,34 @@ | |||
| package mate.academy; | |||
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| package mate.academy; | |
| package mate.academy.util; |
| statement.setLong(1, id); | ||
| ResultSet resultSet = statement.executeQuery(); | ||
| if (resultSet.next()) { | ||
| String title = resultSet.getString("title"); |
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create separate methods to map result set to book
| PreparedStatement statement = connection.prepareStatement(sql)) { | ||
| ResultSet resultSet = statement.executeQuery(); | ||
| while (resultSet.next()) { | ||
| Long id = resultSet.getObject("id", Long.class); |
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use separate method from comment above
src/main/resources/init_db.sql
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| USE `intro`; | ||
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| CREATE TABLE `books` ( | ||
| `id` INT NOT NULL AUTO_INCREMENT, |
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| `id` INT NOT NULL AUTO_INCREMENT, | |
| `id` BIGINT AUTO_INCREMENT, |
src/main/resources/init_db.sql
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| CREATE TABLE `books` ( | ||
| `id` INT NOT NULL AUTO_INCREMENT, | ||
| `title` VARCHAR(255), | ||
| `price` INT, |
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| `price` INT, | |
| `price` DECIMAL, |
| private Book mapToBook(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; | ||
| } |
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Private methods should be after all public
| if (affectedRows < 1) { | ||
| throw new DataProcessingException( | ||
| "Expected to update at least one row, but updated 0 rows."); | ||
| } |
| statement.setLong(3, book.getId()); | ||
| statement.setString(1, book.getTitle()); | ||
| statement.setBigDecimal(2, book.getPrice()); |
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| statement.setLong(3, book.getId()); | |
| statement.setString(1, book.getTitle()); | |
| statement.setBigDecimal(2, book.getPrice()); | |
| statement.setString(1, book.getTitle()); | |
| statement.setBigDecimal(2, book.getPrice()); | |
| statement.setLong(3, book.getId()); | |
…k in BookDaoImpl.
src/main/resources/init_db.sql
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| USE `intro`; | ||
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| CREATE TABLE `books` ( | ||
| `id` INT NOT NULL AUTO_INCREMENT, |
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