This is a huge coincidence, but I was just logging in to ask what I believe
is the same question.
Let's say was have a table of books and a table of authors. I want to
return a list of instances of Book, but with attached Author instances as
well (which I can access using Book.getAuthors()). For better efficiency
and for atomicity, I suppose I can do a join, which won't return me a
BookRecord anymore. Moreover, as there could be many, many books returned,
I use fetchLazy() to give me a cursor. As far as I can tell, I have to do
this:
List<Book> bookList=new ArrayList<Book>();
Book currentBook=null;
Author currentAuthor=null;
while(cursor.hasNext()) {
Record record=cursor.fetchOne();
String bookID=record.getValue(BOOK.ID);
//if we are changing books
if(currentBook==null || !currentBook.getID.equals(bookID) {
//if we were populating a book
if(currentBook!=null) {
bookList.add(currentBook);
}
//start a new book
currentBook=new Book(bookID);
currentAuthor=null;
currentBook.setTitle(record.getValue(BOOK.TITLE));
...
}
String authorID=record.getValue(AUTHOR.ID);
if(currentAuthor==null || !currentAuthor.getID().equals(authorID)) {
if(currentAuthor!=null) {
currentBook.addAuthor(author);
}
currentAuthor=new Author();
currentAuthor.setLastName(record.getValue(AUTHOR.LAST_NAME));
...
And so it goes. Because a join will produce records with duplicated
information for the objects in one-to-many relationships, I'll have to have
this bulky logic for detecting when an instance changes, correct? But that
is so tedious!! I could instead do multiple queries to create the instances
as I walk the graph---but isn't that less efficient and not atomic?
What does jOOQ expect us to do to retrieve instance graphs in an efficient
way?
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