com.avaje.ebean.PagingList Maven / Gradle / Ivy
package com.avaje.ebean;
import java.util.List;
import java.util.concurrent.Future;
/**
* Used to page through a query result rather than fetching all the results in a
* single query.
*
* Has the ability to use background threads to 'fetch ahead' the next page and
* get the total row count.
*
*
* If you are building a stateless web application and not keeping the
* PagingList over multiple requests then there is not much to be gained in
* using PagingList. Instead you can just use {@link Query#setFirstRow(int)} and
* {@link Query#setMaxRows(int)}.
*
*
*
* If you are using PagingList is a stateful web application where the
* PagingList is held over multiple requests then PagingList provides the extra
* benefits of
*
* - Fetch ahead - automatically fetching the next page via background query
* execution
* - Automatic propagation of the persistence context
*
*
*
* So with PagingList when you use Page 2 it can automatically fetch Page 3 data
* in the background (using a findFutureList() query). It also automatically
* propagates the persistence context so that all the queries executed by the
* PagingList all use the same persistence context.
*
*
*
* PagingList<TOne> pagingList =
* Ebean.find(TOne.class)
* .where().gt("name", "2")
* .findPagingList(10);
*
* // get the row count in the background...
* // ... otherwise it is fetched on demand
* // ... when getRowCount() or getPageCount()
* // ... is called
* pagingList.getFutureRowCount();
*
* // get the first page
* Page<TOne> page = pagingList.getPage(0);
*
* // get the beans from the page as a list
* List<TOne> list = page.getList();
*
*
* @author rbygrave
*
* @param
* the entity bean type
*/
public interface PagingList {
/**
* Refresh will clear all the pages and row count forcing them to be
* re-fetched when next required.
*/
public void refresh();
// public void fetchAll();
// public String? getOrderBy();
// public void setOrderBy(String?);
/**
* By default fetchAhead is true so use this to turn off fetchAhead.
*
* Set this to false if you don't want to fetch ahead using background
* fetching.
*
* If set to true (or left as to default) then the next page is fetched in the
* background as soon as the list is accessed.
*
*/
public PagingList setFetchAhead(boolean fetchAhead);
/**
* Return the Future for getting the total row count.
*/
public Future getFutureRowCount();
/**
* Return the data for all the pages in the form of a single List.
*
* Iterating through this list will automatically fire the paging queries as
* required.
*
*/
public List getAsList();
/**
* Return the page size. This is the number of rows per page.
*/
public int getPageSize();
/**
* Return the total row count.
*
* This gets the result from getFutureRowCount and will wait until that query
* has completed.
*
*/
public int getTotalRowCount();
/**
* Return the total page count.
*
* This is based on the total row count. This will wait until the row count
* has returned if it has not already.
*
*/
public int getTotalPageCount();
/**
* Return the page for a given page position (starting at 0).
*/
public Page getPage(int i);
}