Paginated results

The Query API includes methods for returning paginated results. A paginated result prevents all query results from being returned at one time, potentially exceeding system memory. It allows you to incrementally return and process query results in batches.

In the following snippet, a PaginatedResult object is returned that is limited to the first 10 User objects.

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PaginatedResult<User> results = Query.from(User.class)
①
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                                      .select(0, 10);
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 List<User> users = results.getItems();
②

• ①Returns a PaginatedResult with select(long offset, int limit). This method specifies the number of objects to return starting at a particular offset. If the offset were set to 5 and the limit set to 15, the method would return 15 instances starting at offset 5.
• ②Returns the objects contained by PaginatedResult.

The PaginatedResult object only contains the number of objects specified in select(long offset, int limit), which is typically a subset of the total objects retrieved. For example, a query might return a total of 1,000 objects, which can be determined with the getCount method on PaginatedResult.

To iterate query results in batches, use the PaginatedResult methods hasNext() and getNextOffset(). The following snippet builds paginated results in batches of 100 objects.

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int limit = 100;
①
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Query<User> query = Query.from(User.class);
②
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PaginatedResult<User> result = query.select(0, limit);
③
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while (result.hasNext()) {
④
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    /* Do something with the current batch of items referenced in the result object */
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    result = query.select(result.getNextOffset(), limit);
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}

• ①Variable for limiting the number of retrieved records in a page.
• ②Instantiates a Query object for searching users.
• ③Returns a PaginatedResult with the first 100 User objects.
• ④Iterates PaginatedResult in batches of 100 items. Successive iterations continue until all of the objects retrieved by the query are processed.