Database Reference
In-Depth Information
if(book!=null)
System.out.println(book.getBookTitle() + "\t" +
book.getEdition()
+ "\t" + book.getLanguage());
book1.setLanguage(new HashSet<String>(
Arrays.asList("English", "German", "Latin")));
dynamoDBMapper.save(book1);
} catch (ConditionalCheckFailedException e) {
System.out.println(e.getMessage());
}
Running the preceding code will not give any error because we get the
BookEntity
item using the key values
Hadoop
and
2012-12-28
. Then, we set the
Language
set
to hold English and German strings to the returned
BookEntity
item and save it (which
ends the first transaction and updates the version attribute). The code will print the follow-
ing output:
Hadoop 1 [Latin, German, English]
Hadoop 1 [German, English]
Running the following code will result in
ConditionalCheckFailedException
.
It is exactly the same as that of the previous code, except for the location of
dy-
namoDBMapper.save(book)
:
try {
BookEntity book = dynamoDBMapper.load(
BookEntity.class, "Hadoop","2012-12-28");
if(book!=null)
System.out.println(book.getBookTitle()
+ "\t" + book.getEdition() + "\t" +
book.getLanguage());
book.setLanguage(new
HashSet<String>(Arrays.asList("English", "German")));
BookEntity book1 = dynamoDBMapper.load(
BookEntity.class, "Hadoop","2012-12-28");
if(book!=null)
System.out.println(book.getBookTitle() + "\t" +
book.getEdition()
