Objectify paging with Cursors

Question

I have this method in my RPC service:

@Override
    public Entrata[] getEntrate(int from, int to) {
        List data = entrateDao.list();
            


        

Answer 1

I just want make sure you don't have any errors in your code since you can copy and past the Igor Artamonov code. Here is a cleaner code from Objectify Wiki with less errors and some documentation:

// create the query and set the limit to 1000
Query query = ofy().load().type(Car.class).limit(1000);

// Here you get the cursor (if exists) from the request
// For the first request, i-e the first page, this parameter(cursor) will be null
String cursorStr = request.getParameter("cursor");

// Here you check if cursor is not null and not empty
// If so, we start our query from the last check point
if (cursorStr != null && !cursorStr.isEmpty())
    query = query.startAt(Cursor.fromWebSafeString(cursorStr));

// We need this variable to know when we have been loaded all the entries
boolean remaining = false;
QueryResultIterator iterator = query.iterator();
while (iterator.hasNext()) {
    Car car = iterator.next();

    ... // your code here

    // We have found entries, so we set this variable to true.
    // That means, we have probably another page to fetch
    remaining = true;
}

// If we have found entries, we send the last check point
if (remaining) {
    // we take the last check point by calling "toWebSafeString()" from the iterator's cursor
    Cursor cursor = iterator.getCursor();
    Queue queue = QueueFactory.getDefaultQueue();
    queue.add(url("/pathToThisServlet").param("cursor", cursor.toWebSafeString()));
}