DATACMNS-802 - PagedResourceAssembler now allows customizing the PagedResource instance.

Introduced a template method to override the creation of a PagedResource to allow subclasses to create a more concrete instance than PagedResource itself.

Author: odrotbohm

src/main/java/org/springframework/data/web/PagedResourcesAssembler.java

@@ -170,6 +170,24 @@ public Link appendPaginationParameterTemplates(Link link) {
 		return createLink(new UriTemplate(link.getHref()), null, link.getRel());
 	}
 
+	/**
+	 * Creates the {@link PagedResources} to be equipped with pagination links downstream.
+	 * 
+	 * @param resources the original page's elements mapped into {@link ResourceSupport} instances.
+	 * @param metadata the calculated {@link PageMetadata}, must not be {@literal null}.
+	 * @param page the original page handed to the assembler, must not be {@literal null}.
+	 * @return must not be {@literal null}.
+	 */
+	protected <R extends ResourceSupport, S> PagedResources<R> createPagedResource(List<R> resources,
+			PageMetadata metadata, Page<S> page) {
+
+		Assert.notNull(resources, "Content resources must not be null!");
+		Assert.notNull(metadata, "PageMetadata must not be null!");
+		Assert.notNull(page, "Page must not be null!");
+
+		return new PagedResources<R>(resources, metadata);
+	}
+
 	private <S, R extends ResourceSupport> PagedResources<R> createResource(Page<S> page,
 			ResourceAssembler<S, R> assembler, Link link) {
 
@@ -182,7 +200,9 @@ private <S, R extends ResourceSupport> PagedResources<R> createResource(Page<S>
 			resources.add(assembler.toResource(element));
 		}
 
-		return addPaginationLinks(new PagedResources<R>(resources, asPageMetadata(page)), page, link);
+		PagedResources<R> resource = createPagedResource(resources, asPageMetadata(page), page);
+
+		return addPaginationLinks(resource, page, link);
 	}
 
 	private <R> PagedResources<R> addPaginationLinks(PagedResources<R> resources, Page<?> page, Link link) {

src/test/java/org/springframework/data/web/PagedResourcesAssemblerUnitTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2015 the original author or authors.
+ * Copyright 2013-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,6 +22,7 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.List;
 import java.util.Map;
 
 import org.junit.Before;
@@ -33,6 +34,7 @@
 import org.springframework.data.domain.Pageable;
 import org.springframework.hateoas.Link;
 import org.springframework.hateoas.PagedResources;
+import org.springframework.hateoas.PagedResources.PageMetadata;
 import org.springframework.hateoas.Resource;
 import org.springframework.hateoas.ResourceAssembler;
 import org.springframework.hateoas.ResourceSupport;
@@ -273,6 +275,18 @@ public void alwaysAddsFirstAndLastLinkIfConfiguredTo() {
 		assertThat(resources.getLink(Link.REL_LAST).getHref(), endsWith("?page=0&size=20"));
 	}
 
+	/**
+	 * @see DATACMNS-802
+	 */
+	@Test
+	public void usesCustomPagedResources() {
+
+		ResourceAssembler<Page<Person>, PagedResources<Resource<Person>>> assembler = new CustomPagedResourcesAssembler<Person>(
+				resolver, null);
+
+		assertThat(assembler.toResource(EMPTY_PAGE), is(instanceOf(CustomPagedResources.class)));
+	}
+
 	private static Page<Person> createPage(int index) {
 
 		AbstractPageRequest request = new PageRequest(index, 1);
@@ -310,4 +324,24 @@ public PersonResource toResource(Person entity) {
 			return resource;
 		}
 	}
+
+	static class CustomPagedResourcesAssembler<T> extends PagedResourcesAssembler<T> {
+
+		public CustomPagedResourcesAssembler(HateoasPageableHandlerMethodArgumentResolver resolver, UriComponents baseUri) {
+			super(resolver, baseUri);
+		}
+
+		@Override
+		protected <R extends ResourceSupport, S> PagedResources<R> createPagedResource(List<R> resources,
+				PageMetadata metadata, Page<S> page) {
+			return new CustomPagedResources<R>(resources, metadata);
+		}
+	}
+
+	static class CustomPagedResources<R extends ResourceSupport> extends PagedResources<R> {
+
+		public CustomPagedResources(Collection<R> content, PageMetadata metadata) {
+			super(content, metadata);
+		}
+	}
 }