Issues/1300 Fluent API for PagedModel

src/main/java/org/springframework/hateoas/AbstractCollectionModel.java

@@ -0,0 +1,114 @@
+/*
+ * Copyright 2012-2020 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.hateoas;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.Objects;
+
+/**
+ * General helper to easily create a wrapper for a collection of entities.
+ *
+ * @author Oliver Gierke
+ * @author Greg Turnquist
+ */
+public class AbstractCollectionModel<T, S extends AbstractCollectionModel<T, S>> extends RepresentationModel<S> implements Iterable<T> {
+
+	private final Collection<T> content;
+
+	public AbstractCollectionModel() {
+		this(new ArrayList<>(), Collections.emptyList());
+	}
+
+	/**
+	 * Creates a {@link AbstractCollectionModel} instance with the given content and {@link Link}s.
+	 *
+	 * @param content must not be {@literal null}.
+	 * @param links the links to be added to the {@link AbstractCollectionModel}.
+	 */
+	protected AbstractCollectionModel(Iterable<T> content, Iterable<Link> links) {
+
+		Assert.notNull(content, "Content must not be null!");
+
+		this.content = new ArrayList<>();
+
+		for (T element : content) {
+			this.content.add(element);
+		}
+
+		this.add(links);
+	}
+
+	/**
+	 * Returns the underlying elements.
+	 *
+	 * @return the content will never be {@literal null}.
+	 */
+	@JsonProperty("content")
+	public Collection<T> getContent() {
+		return Collections.unmodifiableCollection(content);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see java.lang.Iterable#iterator()
+	 */
+	@Override
+	public Iterator<T> iterator() {
+		return content.iterator();
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.hateoas.ResourceSupport#equals(java.lang.Object)
+	 */
+	@Override
+	public boolean equals(@Nullable Object obj) {
+
+		if (obj == this) {
+			return true;
+		}
+
+		if (obj == null || !obj.getClass().equals(getClass())) {
+			return false;
+		}
+
+		if (!super.equals(obj)) {
+			return false;
+		}
+
+		AbstractCollectionModel<?, ?> that = (AbstractCollectionModel<?, ?>) obj;
+		return Objects.equals(this.content, that.content);
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.hateoas.ResourceSupport#hashCode()
+	 */
+	@Override
+	public int hashCode() {
+		int result = super.hashCode();
+		result += 17 * Objects.hashCode(content);
+		return result;
+	}
+
+}

src/main/java/org/springframework/hateoas/CollectionModel.java

@@ -17,24 +17,17 @@
 
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collection;
 import java.util.Collections;
-import java.util.Iterator;
 
-import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
-import com.fasterxml.jackson.annotation.JsonProperty;
-
 /**
  * General helper to easily create a wrapper for a collection of entities.
  *
  * @author Oliver Gierke
  * @author Greg Turnquist
  */
-public class CollectionModel<T> extends RepresentationModel<CollectionModel<T>> implements Iterable<T> {
-
-	private final Collection<T> content;
+public class CollectionModel<T> extends AbstractCollectionModel<T, CollectionModel<T>> implements Iterable<T> {
 
 	/**
 	 * Creates an empty {@link CollectionModel} instance.
@@ -64,16 +57,7 @@ public CollectionModel(Iterable<T> content, Link... links) {
 	 */
 	@Deprecated
 	public CollectionModel(Iterable<T> content, Iterable<Link> links) {
-
-		Assert.notNull(content, "Content must not be null!");
-
-		this.content = new ArrayList<>();
-
-		for (T element : content) {
-			this.content.add(element);
-		}
-
-		this.add(links);
+		super(content, links);
 	}
 
 	/**
@@ -115,7 +99,6 @@ public static <T> CollectionModel<T> empty(Iterable<Link> links) {
 	 * Creates a {@link CollectionModel} instance with the given content.
 	 *
 	 * @param content must not be {@literal null}.
-	 * @param links the links to be added to the {@link CollectionModel}.
 	 * @return
 	 * @since 1.1
 	 */
@@ -168,25 +151,6 @@ public static <T extends EntityModel<S>, S> CollectionModel<T> wrap(Iterable<S>
 		return CollectionModel.of(resources);
 	}
 
-	/**
-	 * Returns the underlying elements.
-	 *
-	 * @return the content will never be {@literal null}.
-	 */
-	@JsonProperty("content")
-	public Collection<T> getContent() {
-		return Collections.unmodifiableCollection(content);
-	}
-
-	/*
-	 * (non-Javadoc)
-	 * @see java.lang.Iterable#iterator()
-	 */
-	@Override
-	public Iterator<T> iterator() {
-		return content.iterator();
-	}
-
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.hateoas.ResourceSupport#toString()
@@ -196,37 +160,4 @@ public String toString() {
 		return String.format("Resources { content: %s, %s }", getContent(), super.toString());
 	}
 
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.hateoas.ResourceSupport#equals(java.lang.Object)
-	 */
-	@Override
-	public boolean equals(@Nullable Object obj) {
-
-		if (obj == this) {
-			return true;
-		}
-
-		if (obj == null || !obj.getClass().equals(getClass())) {
-			return false;
-		}
-
-		CollectionModel<?> that = (CollectionModel<?>) obj;
-
-		boolean contentEqual = this.content == null ? that.content == null : this.content.equals(that.content);
-		return contentEqual && super.equals(obj);
-	}
-
-	/*
-	 * (non-Javadoc)
-	 * @see org.springframework.hateoas.ResourceSupport#hashCode()
-	 */
-	@Override
-	public int hashCode() {
-
-		int result = super.hashCode();
-		result += content == null ? 0 : 17 * content.hashCode();
-
-		return result;
-	}
 }

src/main/java/org/springframework/hateoas/EntityModel.java

@@ -78,7 +78,6 @@ public EntityModel(T content, Iterable<Link> links) {
 	 * Creates a new {@link EntityModel} with the given content.
 	 *
 	 * @param content must not be {@literal null}.
-	 * @param links the links to add to the {@link EntityModel}.
 	 * @return
 	 * @since 1.1
 	 */

src/main/java/org/springframework/hateoas/PagedModel.java

@@ -19,6 +19,7 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Objects;
 import java.util.Optional;
 
 import org.springframework.lang.Nullable;
@@ -33,7 +34,7 @@
  * @author Oliver Gierke
  * @author Greg Turnquist
  */
-public class PagedModel<T> extends CollectionModel<T> {
+public class PagedModel<T> extends AbstractCollectionModel<T, PagedModel<T>> {
 
 	public static PagedModel<?> NO_PAGE = new PagedModel<>();
 
@@ -153,7 +154,6 @@ public static <T> PagedModel<T> empty(@Nullable PageMetadata metadata, Iterable<
 	 *
 	 * @param content must not be {@literal null}.
 	 * @param metadata can be {@literal null}.
-	 * @param links
 	 */
 	public static <T> PagedModel<T> of(Collection<T> content, @Nullable PageMetadata metadata) {
 		return new PagedModel<>(content, metadata);
@@ -256,10 +256,12 @@ public boolean equals(@Nullable Object obj) {
 			return false;
 		}
 
-		PagedModel<?> that = (PagedModel<?>) obj;
-		boolean metadataEquals = this.metadata == null ? that.metadata == null : this.metadata.equals(that.metadata);
+		if (!super.equals(obj)) {
+			return false;
+		}
 
-		return metadataEquals && super.equals(obj);
+		PagedModel<?> that = (PagedModel<?>) obj;
+		return Objects.equals(this.metadata, that.metadata);
 	}
 
 	/*
@@ -270,7 +272,7 @@ public boolean equals(@Nullable Object obj) {
 	public int hashCode() {
 
 		int result = super.hashCode();
-		result += this.metadata == null ? 0 : 31 * this.metadata.hashCode();
+		result += 31 * Objects.hashCode(this.metadata);
 		return result;
 	}
 

src/main/java/org/springframework/hateoas/mediatype/JacksonHelper.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.hateoas.mediatype;
 
+import org.springframework.hateoas.AbstractCollectionModel;
 import org.springframework.hateoas.CollectionModel;
 import org.springframework.hateoas.EntityModel;
 
@@ -49,7 +50,7 @@ public static JavaType findRootType(JavaType contentType) {
 	public static boolean isResourcesOfResource(JavaType type) {
 
 		return
-			CollectionModel.class.isAssignableFrom(type.getRawClass())
+			AbstractCollectionModel.class.isAssignableFrom(type.getRawClass())
 			&&
 			EntityModel.class.isAssignableFrom(type.containedType(0).getRawClass());
 	}

src/main/java/org/springframework/hateoas/mediatype/collectionjson/Jackson2CollectionJsonModule.java

@@ -23,6 +23,7 @@
 import java.util.function.Function;
 import java.util.stream.Collectors;
 
+import org.springframework.hateoas.AbstractCollectionModel;
 import org.springframework.hateoas.Affordance;
 import org.springframework.hateoas.CollectionModel;
 import org.springframework.hateoas.EntityModel;
@@ -460,8 +461,7 @@ static class CollectionJsonPagedResourcesSerializer extends ContainerSerializer<
 		}
 
 		CollectionJsonPagedResourcesSerializer(@Nullable BeanProperty property) {
-
-			super(CollectionModel.class, false);
+			super(PagedModel.class, false);
 			this.property = property;
 		}
 
@@ -793,22 +793,22 @@ public JsonDeserializer<?> createContextual(DeserializationContext ctxt, BeanPro
 		}
 	}
 
-	static abstract class CollectionJsonDeserializerBase<T extends CollectionModel<?>>
+	static abstract class AbstractCollectionJsonDeserializer<T extends AbstractCollectionModel<?, ?>>
 			extends ContainerDeserializerBase<T> implements ContextualDeserializer {
 
 		private static final long serialVersionUID = 1007769482339850545L;
 
 		private final JavaType contentType;
 		private final BiFunction<List<Object>, Links, T> finalizer;
-		private final Function<JavaType, CollectionJsonDeserializerBase<T>> creator;
+		private final Function<JavaType, AbstractCollectionJsonDeserializer<T>> creator;
 
-		CollectionJsonDeserializerBase(BiFunction<List<Object>, Links, T> finalizer,
-				Function<JavaType, CollectionJsonDeserializerBase<T>> creator) {
+		AbstractCollectionJsonDeserializer(BiFunction<List<Object>, Links, T> finalizer,
+				Function<JavaType, AbstractCollectionJsonDeserializer<T>> creator) {
 			this(TypeFactory.defaultInstance().constructType(CollectionJson.class), finalizer, creator);
 		}
 
-		private CollectionJsonDeserializerBase(JavaType contentType, BiFunction<List<Object>, Links, T> finalizer,
-				Function<JavaType, CollectionJsonDeserializerBase<T>> creator) {
+		private AbstractCollectionJsonDeserializer(JavaType contentType, BiFunction<List<Object>, Links, T> finalizer,
+				Function<JavaType, AbstractCollectionJsonDeserializer<T>> creator) {
 
 			super(contentType);
 
@@ -883,11 +883,11 @@ public T deserialize(JsonParser parser, DeserializationContext ctxt) throws IOEx
 		}
 	}
 
-	static class CollectionJsonResourcesDeserializer extends CollectionJsonDeserializerBase<CollectionModel<?>> {
+	static class CollectionJsonResourcesDeserializer extends AbstractCollectionJsonDeserializer<CollectionModel<?>> {
 
 		private static final long serialVersionUID = 6406522912020578141L;
 		private static final BiFunction<List<Object>, Links, CollectionModel<?>> FINISHER = CollectionModel::of;
-		private static final Function<JavaType, CollectionJsonDeserializerBase<CollectionModel<?>>> CONTEXTUAL_CREATOR = CollectionJsonResourcesDeserializer::new;
+		private static final Function<JavaType, AbstractCollectionJsonDeserializer<CollectionModel<?>>> CONTEXTUAL_CREATOR = CollectionJsonResourcesDeserializer::new;
 
 		CollectionJsonResourcesDeserializer() {
 			super(FINISHER, CONTEXTUAL_CREATOR);
@@ -898,12 +898,12 @@ private CollectionJsonResourcesDeserializer(JavaType contentType) {
 		}
 	}
 
-	static class CollectionJsonPagedResourcesDeserializer extends CollectionJsonDeserializerBase<PagedModel<?>> {
+	static class CollectionJsonPagedResourcesDeserializer extends AbstractCollectionJsonDeserializer<PagedModel<?>> {
 
 		private static final long serialVersionUID = -7465448422501330790L;
 		private static final BiFunction<List<Object>, Links, PagedModel<?>> FINISHER = (content, links) -> PagedModel
 				.of(content, null, links);
-		private static final Function<JavaType, CollectionJsonDeserializerBase<PagedModel<?>>> CONTEXTUAL_CREATOR = CollectionJsonPagedResourcesDeserializer::new;
+		private static final Function<JavaType, AbstractCollectionJsonDeserializer<PagedModel<?>>> CONTEXTUAL_CREATOR = CollectionJsonPagedResourcesDeserializer::new;
 
 		CollectionJsonPagedResourcesDeserializer() {
 			super(FINISHER, CONTEXTUAL_CREATOR);
@@ -914,7 +914,7 @@ private CollectionJsonPagedResourcesDeserializer(JavaType contentType) {
 		}
 	}
 
-	private static List<CollectionJsonItem<Object>> resourcesToCollectionJsonItems(CollectionModel<?> resources) {
+	private static List<CollectionJsonItem<Object>> resourcesToCollectionJsonItems(AbstractCollectionModel<?, ?> resources) {
 
 		return resources.getContent().stream().map(content -> {
 

src/main/java/org/springframework/hateoas/mediatype/hal/CollectionModelMixin.java

@@ -27,7 +27,7 @@
 import com.fasterxml.jackson.databind.annotation.JsonSerialize;
 
 /**
- * Custom mixin to to render collection content as {@literal _embedded}.
+ * Custom mixin to render collection content as {@literal _embedded}.
  *
  * @author Alexander Baetz
  * @author Oliver Gierke