added necessary methods #321
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src/main/java/mate/academy/Main.java
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| BookDao bookDao = (BookDao) injector.getInstance(BookDao.class); | ||
| Book bookJava = new Book(); | ||
| bookJava.setTitle("Java"); | ||
| bookJava.setPrice(BigDecimal.valueOf(350.00)); | ||
| bookDao.create(bookJava); | ||
| Book bookHistory = new Book(); | ||
| bookHistory.setTitle("History"); | ||
| bookHistory.setPrice(BigDecimal.valueOf(350.00)); | ||
| bookDao.create(bookHistory); | ||
| Optional<Book> optional = bookDao.findById(3L); | ||
| Book book = optional.get(); | ||
| System.out.println(book); | ||
| List<Book> list = bookDao.findAll(); | ||
| System.out.println(list); | ||
| bookDao.deleteById(1L); |
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this is hard to read, let's try to do something about it
| public class BookDaoImpl implements BookDao { | ||
| @Override | ||
| public Book create(Book book) { | ||
| String sql = "INSERT INTO book(title,price) VALUE(?, ?)"; |
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this var could use a better naming, same for similar ones in other methods
| statement.setString(1, book.getTitle()); | ||
| statement.setBigDecimal(2,book.getPrice()); | ||
| int affectedRows = statement.executeUpdate(); | ||
| if (affectedRows < 1) { |
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magic numbers, check other methods as well
| statement.setBigDecimal(2,book.getPrice()); | ||
| int affectedRows = statement.executeUpdate(); | ||
| if (affectedRows < 1) { | ||
| throw new RuntimeException("Expected to insert at least one row," |
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use custom exception that we have created
| PreparedStatement statement = connection.prepareStatement(sql)) { | ||
| ResultSet resultSet = statement.executeQuery(); | ||
| while (resultSet.next()) { | ||
| long id = resultSet.getInt("id"); |
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Why int if the book has Long field? Also, check common mistakes about that getLong()
| long id = resultSet.getInt("id"); | ||
| String title = resultSet.getString("title"); | ||
| BigDecimal price = resultSet.getBigDecimal("price"); | ||
| Book book = new Book(); | ||
| book.setId(id); | ||
| book.setPrice(price); | ||
| book.setTitle(title); | ||
| books.add(book); |
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code duplication of getting a Book from ResultSet, move it to some parseBook() method
| long id = resultSet.getInt("id"); | ||
| String title = resultSet.getString("title"); | ||
| BigDecimal price = resultSet.getBigDecimal("price"); |
| books.add(book); | ||
| } | ||
| } catch (SQLException e) { | ||
| throw new DataProcessingException("Can't create a new connection to the DB", e); |
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SQLException reason can be anything basically, not just the connection problem, so we can not be that specific in that case, but e will provide us wit everything we need to fix the problem in case we encounter it
| throw new DataProcessingException("Can't create a new connection to the DB", e); | |
| throw new DataProcessingException("Can't find all books", e); |
src/main/resources/init_db.sql
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| `title` VARCHAR(255), | ||
| `price` DECIMAL(10, 2), | ||
| PRIMARY KEY(`id`) | ||
| ); |
| newBook.setTitle(resultSet.getObject(TITLE_COLUMN, String.class)); | ||
| newBook.setPrice(resultSet.getObject(PRICE_COLUMN, BigDecimal.class)); |
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in the case of String and BigDecimal, it is actually fine to use getString() and .getBigDecimal() because it is already an object, when with case of getLong() it returns a primitive(which can not be null) and thus we have to use getObject() instead.
It's fine to leave it as it is, just wanted you to know 😉
| statement.setLong(KEY_POSITION_INDEX, book.getId()); | ||
| int affectedRows = statement.executeUpdate(); | ||
| if (affectedRows == EXCEPTION_AFFECTED_ROWS) { | ||
| throw new RuntimeException("Updating book failed, no rows affected."); |
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I'd also replace this ex to DataProcessingException
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