#482 - Add support for Collection+JSON mediatype.

Introduce support for media type application/vnd.collection+json. Collection+JSON doesn't allow metadata at the top, so paging data can't be covered, however, everything else fits.

Also moved a little bit more into Affordance and SpringMvcAffordance to avoid using Spring MVC annotations directly in a given mediatype's AffordanceModel.

Refactored bits of HAL-FORMS to reuse the new PropertyUtils, ensuring Jackson ignore annotations are taken into consideration. Also added MockMVC tests to show HAL-FORMS and Collection+JSON working together, against the same controller.

readme.adoc

@@ -0,0 +1,21 @@
+image:https://spring.io/badges/spring-hateoas/ga.svg[http://projects.spring.io/spring-hateoas/#quick-start]
+image:https://spring.io/badges/spring-hateoas/snapshot.svg[http://projects.spring.io/spring-hateoas/#quick-start]
+
+= Spring HATEOAS
+
+This project provides some APIs to ease creating REST representations that follow the http://en.wikipedia.org/wiki/HATEOAS[HATEOAS] principle when working with Spring and especially Spring MVC. The core problem it tries to address is link creation and representation assembly.
+
+== Working with Spring HATEOAS
+
+Since all commits are headlined with its github issue, git will treat it as a comment. To get around this, apply the following configuration to your clone:
+
+[source]
+----
+git config core.commentchar "/"
+----
+
+== Resources
+
+* Reference documentation - http://docs.spring.io/spring-hateoas/docs/current/reference/html/[html], http://docs.spring.io/spring-hateoas/docs/current/reference/pdf/spring-hateoas-reference.pdf[pdf]
+* http://docs.spring.io/spring-hateoas/docs/current-SNAPSHOT/api/[JavaDoc]
+* https://spring.io/guides/gs/rest-hateoas/[Getting started guide]

src/main/asciidoc/index.adoc

@@ -363,7 +363,7 @@ Since the purpose of the `CurieProvider` API is to allow for automatic curie cre
 [[client.traverson]]
 === Traverson
 
-As of version 0.11 Spring HATEOAS provides an API for client side service traversal inspired by the https://blog.codecentric.de/en/2013/11/traverson/[Traverson JavaScript library].
+Spring HATEOAS provides an API for client side service traversal inspired by the https://blog.codecentric.de/en/2013/11/traverson/[Traverson JavaScript library].
 
 [source, java]
 ----

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

@@ -15,6 +15,9 @@
  */
 package org.springframework.hateoas;
 
+import java.util.List;
+
+import org.springframework.core.MethodParameter;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.MediaType;
 
@@ -47,4 +50,17 @@ public interface Affordance {
 	 * @return
 	 */
 	<T extends AffordanceModel> T getAffordanceModel(MediaType mediaType);
+
+	/**
+	 * Get a listing of {@link MethodParameter}s.
+	 *
+	 * @return
+	 */
+	List<MethodParameter> getInputMethodParameters();
+
+	/**
+	 * Get a listing of {@link QueryParameter}s.
+	 * @return
+	 */
+	List<QueryParameter> getQueryMethodParameters();
 }

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

@@ -49,7 +49,7 @@
  */
 @XmlType(name = "link", namespace = Link.ATOM_NAMESPACE)
 @JsonInclude(JsonInclude.Include.NON_NULL)
-@JsonIgnoreProperties("templated")
+@JsonIgnoreProperties(value = "templated", ignoreUnknown = true)
 @AllArgsConstructor(access = AccessLevel.PACKAGE)
 @Getter
 @EqualsAndHashCode(of = { "rel", "href", "hreflang", "media", "title", "deprecation", "affordances" })

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

@@ -67,4 +67,13 @@ public class MediaTypes {
 	 */
 	public static final MediaType HAL_FORMS_JSON = MediaType.parseMediaType(HAL_FORMS_JSON_VALUE);
 
+	/**
+	 * A String equivalent of {@link MediaTypes#COLLECTION_JSON}.
+	 */
+	public static final String COLLECTION_JSON_VALUE = "application/vnd.collection+json";
+
+	/**
+	 * Public constant media type for {@code application/vnd.collection+json}.
+	 */
+	public static final MediaType COLLECTION_JSON = MediaType.valueOf(COLLECTION_JSON_VALUE);
 }

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

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2018 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
+ *
+ *      http://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 lombok.Data;
+import lombok.RequiredArgsConstructor;
+
+/**
+ * Web framework-neutral representation of a web request's query parameter (http://example.com?name=foo).
+ *
+ * @author Greg Turnquist
+ */
+@Data
+@RequiredArgsConstructor
+public class QueryParameter {
+
+	private final String name;
+	private final boolean required;
+	private final String value;
+}

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

@@ -29,6 +29,7 @@
  * A simple {@link Resource} wrapping a domain object and adding links to it.
  * 
  * @author Oliver Gierke
+ * @author Greg Turnquist
  */
 @XmlRootElement
 public class Resource<T> extends ResourceSupport {
@@ -38,7 +39,7 @@ public class Resource<T> extends ResourceSupport {
 	/**
 	 * Creates an empty {@link Resource}.
 	 */
-	Resource() {
+	protected Resource() {
 		this.content = null;
 	}
 

src/main/java/org/springframework/hateoas/collectionjson/CollectionJson.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2015 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
+ *
+ *      http://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.collectionjson;
+
+import lombok.AccessLevel;
+import lombok.Value;
+import lombok.experimental.Wither;
+
+import java.util.List;
+
+import org.springframework.hateoas.Link;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.annotation.JsonInclude.Include;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+/**
+ * Representation of the "collection" part of a Collection+JSON document.
+ *
+ * @author Greg Turnquist
+ */
+@Value
+@Wither(AccessLevel.PACKAGE)
+class CollectionJson<T> {
+
+	private String version;
+	private String href;
+
+	@JsonInclude(Include.NON_EMPTY)
+	private List<Link> links;
+
+	@JsonInclude(Include.NON_EMPTY)
+	private List<CollectionJsonItem<T>> items;
+
+	@JsonInclude(Include.NON_EMPTY)
+	private List<CollectionJsonQuery> queries;
+
+	@JsonInclude(Include.NON_NULL)
+	private CollectionJsonTemplate template;
+
+	@JsonInclude(Include.NON_NULL)
+	private CollectionJsonError error;
+
+	@JsonCreator
+	CollectionJson(@JsonProperty("version") String version, @JsonProperty("href") String href,
+				   @JsonProperty("links") List<Link> links, @JsonProperty("items") List<CollectionJsonItem<T>> items,
+				   @JsonProperty("queries") List<CollectionJsonQuery> queries,
+				   @JsonProperty("template") CollectionJsonTemplate template,
+				   @JsonProperty("error") CollectionJsonError error) {
+
+		this.version = version;
+		this.href = href;
+		this.links = links;
+		this.items = items;
+		this.queries = queries;
+		this.template = template;
+		this.error = error;
+	}
+
+	CollectionJson() {
+		this("1.0", null, null, null, null, null, null);
+	}
+}

src/main/java/org/springframework/hateoas/collectionjson/CollectionJsonAffordanceModel.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright 2018 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
+ *
+ *      http://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.collectionjson;
+
+import lombok.Getter;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.springframework.core.ResolvableType;
+import org.springframework.hateoas.Affordance;
+import org.springframework.hateoas.AffordanceModel;
+import org.springframework.hateoas.MediaTypes;
+import org.springframework.hateoas.QueryParameter;
+import org.springframework.hateoas.support.PropertyUtils;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.MediaType;
+import org.springframework.web.util.UriComponents;
+
+/**
+ * @author Greg Turnquist
+ */
+class CollectionJsonAffordanceModel implements AffordanceModel {
+
+	private static final List<HttpMethod> METHODS_FOR_INPUT_DETECTION = Arrays.asList(HttpMethod.POST, HttpMethod.PUT,
+		HttpMethod.PATCH);
+
+	private final Affordance affordance;
+	private final UriComponents components;
+	private final @Getter List<CollectionJsonData> inputProperties;
+	private final @Getter List<CollectionJsonData> queryProperties;
+
+	CollectionJsonAffordanceModel(Affordance affordance, UriComponents components) {
+
+		this.affordance = affordance;
+		this.components = components;
+
+		this.inputProperties = determineAffordanceInputs();
+		this.queryProperties = determineQueryProperties();
+	}
+
+	@Override
+	public Collection<MediaType> getMediaTypes() {
+		return Collections.singleton(MediaTypes.COLLECTION_JSON);
+	}
+
+	public String getRel() {
+		return isHttpGetMethod() ? this.affordance.getName() : "";
+	}
+
+	public String getUri() {
+		return isHttpGetMethod() ? this.components.toUriString() : "";
+	}
+
+	/**
+	 * Transform a list of {@link QueryParameter}s into a list of {@link CollectionJsonData} objects.
+	 * 
+	 * @return
+	 */
+	private List<CollectionJsonData> determineQueryProperties() {
+
+		if (!isHttpGetMethod()) {
+			return Collections.emptyList();
+		}
+
+		return this.affordance.getQueryMethodParameters().stream()
+			.map(queryProperty -> new CollectionJsonData().withName(queryProperty.getName()).withValue(""))
+			.collect(Collectors.toList());
+	}
+
+	private boolean isHttpGetMethod() {
+		return this.affordance.getHttpMethod().equals(HttpMethod.GET);
+	}
+
+	/**
+	 * Look at the inputs for a Spring MVC controller method to decide the {@link Affordance}'s properties.
+	 * Then transform them into a list of {@link CollectionJsonData} objects.
+	 */
+	private List<CollectionJsonData> determineAffordanceInputs() {
+
+		if (!METHODS_FOR_INPUT_DETECTION.contains(affordance.getHttpMethod())) {
+			return Collections.emptyList();
+		}
+
+		return this.affordance.getInputMethodParameters().stream()
+			.findFirst()
+			.map(methodParameter -> {
+				ResolvableType resolvableType = ResolvableType.forMethodParameter(methodParameter);
+				return PropertyUtils.findProperties(resolvableType);
+			})
+			.orElse(Collections.emptyList())
+			.stream()
+			.map(property -> new CollectionJsonData().withName(property).withValue(""))
+			.collect(Collectors.toList());
+	}
+}

src/main/java/org/springframework/hateoas/collectionjson/CollectionJsonAffordanceModelFactory.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2018 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
+ *
+ *      http://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.collectionjson;
+
+import lombok.Getter;
+
+import org.springframework.hateoas.Affordance;
+import org.springframework.hateoas.AffordanceModel;
+import org.springframework.hateoas.MediaTypes;
+import org.springframework.hateoas.core.AffordanceModelFactory;
+import org.springframework.hateoas.core.DummyInvocationUtils.MethodInvocation;
+import org.springframework.http.MediaType;
+import org.springframework.web.util.UriComponents;
+
+/**
+ * @author Greg Turnquist
+ */
+class CollectionJsonAffordanceModelFactory implements AffordanceModelFactory {
+
+	private final @Getter MediaType mediaType = MediaTypes.COLLECTION_JSON;
+
+	/**
+	 * Look up the {@link AffordanceModel} for this factory.
+	 *
+	 * @param affordance
+	 * @param invocationValue
+	 * @param components
+	 * @return
+	 */
+	@Override
+	public AffordanceModel getAffordanceModel(Affordance affordance, MethodInvocation invocationValue, UriComponents components) {
+		return new CollectionJsonAffordanceModel(affordance, components);
+	}
+}