org.axonframework.common.jpa

Class PagingJpaQueryIterable<T,R>

java.lang.Object

org.axonframework.common.jpa.PagingJpaQueryIterable<T,R>

Type Parameters:

T - The query result type.

R - The mapped result type.

All Implemented Interfaces:

Iterable<R>

public class PagingJpaQueryIterable<T,R>
extends Object
implements Iterable<R>

Enables iterating through a JPA query using paging while lazily mapping the results when necessary. Paging is taken care of automatically, fetching the next page when the items run out to iterate through.

Do not use this for paging when you care about concurrent deletes. If you loaded a page, delete an item from it, and load the next, you will miss an item during iteration.

The iterator() function can be called multiple times to loop through the items, restarting the query from the start.

Since:

4.6.0

Author:

Mitchell Herrijgers

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	PagingJpaQueryIterable.PagingIterator The Iterator that loops through the provided query's pages until it runs out of items.

Constructor Summary

Constructors

Constructor and Description
PagingJpaQueryIterable(int pageSize, TransactionManager transactionManager, Supplier<javax.persistence.TypedQuery<T>> querySupplier, Function<T,R> lazyMappingFunction) Constructs a new Iterable using the provided querySupplier to construct queries when a new page needs to be fetched.

Method Summary

Modifier and Type	Method and Description
Iterator<R>	iterator()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

PagingJpaQueryIterable

public PagingJpaQueryIterable(int pageSize,
                              TransactionManager transactionManager,
                              Supplier<javax.persistence.TypedQuery<T>> querySupplier,
                              Function<T,R> lazyMappingFunction)

Constructs a new Iterable using the provided querySupplier to construct queries when a new page needs to be fetched. Items are lazily mapped by the provided lazyMappingFunction when iterating.

Parameters:

pageSize - The size of the pages.

transactionManager - The TransactionManager to use when fetching items.

querySupplier - The supplier of the queries. Will be invoked for each page.

lazyMappingFunction - The mapping function to map items to the desired representation.

Method Detail

iterator

public Iterator<R> iterator()

Specified by:

iterator in interface Iterable<R>