#1157 - Tweaks to EntityModel to allow deserialization with Map<String, Object> content.

We now keep internal methods in EntityModel that are configured using Jackson annotations so that it'd populate the content with a Map in case Map<String, Content> is defined as payload type.

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

@@ -17,10 +17,13 @@ package org.springframework.hateoas;
 
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.LinkedHashMap;
+import java.util.Map;
 
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
+import com.fasterxml.jackson.annotation.JsonAnySetter;
 import com.fasterxml.jackson.annotation.JsonUnwrapped;
 
 /**
@@ -31,7 +34,7 @@ import com.fasterxml.jackson.annotation.JsonUnwrapped;
  */
 public class EntityModel<T> extends RepresentationModel<EntityModel<T>> {
 
-	private final T content;
+	private T content;
 
 	/**
 	 * Creates an empty {@link EntityModel}.
@@ -75,6 +78,25 @@ public class EntityModel<T> extends RepresentationModel<EntityModel<T>> {
 		return content;
 	}
 
+	// Hacks to allow deserialization into an EntityModel<Map<String, Object>>
+
+	@JsonAnySetter
+	private void setPropertiesAsMap(String key, Object value) {
+		getOrInitAsMap().put(key, value);
+	}
+
+	@SuppressWarnings("unchecked")
+	private Map<String, Object> getOrInitAsMap() {
+
+		if (this.content == null) {
+			this.content = (T) new LinkedHashMap<>();
+		} else {
+			Assert.state(Map.class.isInstance(this.content), "Content is not a Map!");
+		}
+
+		return (Map<String, Object>) this.content;
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.hateoas.ResourceSupport#toString()

src/test/java/org/springframework/hateoas/mediatype/hal/Jackson2HalIntegrationTest.java

@@ -46,10 +46,13 @@ import org.springframework.hateoas.server.core.EmbeddedWrappers;
 import org.springframework.hateoas.server.core.Relation;
 import org.springframework.lang.Nullable;
 
+import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JavaType;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.PropertyNamingStrategy;
 import com.fasterxml.jackson.databind.SerializationFeature;
+import com.fasterxml.jackson.databind.type.TypeFactory;
 import com.jayway.jsonpath.DocumentContext;
 import com.jayway.jsonpath.JsonPath;
 
@@ -569,9 +572,36 @@ class Jackson2HalIntegrationTest extends AbstractJackson2MarshallingIntegrationT
 		assertThat(context.read("$.anotherKey", String.class)).isEqualTo("anotherValue");
 	}
 
+	@Test // #1157
+	void deserializesEntityModelForMapCorrectly() throws Exception {
+
+		TypeFactory typeFactory = mapper.getTypeFactory();
+
+		JavaType mapType = typeFactory.constructParametricType(Map.class, String.class, Object.class);
+		JavaType modelType = typeFactory.constructParametricType(EntityModel.class, mapType);
+
+		String source = "{ \"key\" : \"value\" }";
+
+		EntityModel<Map<String, Object>> result = mapper.readValue(source, modelType);
+
+		assertThat(result.getContent()).containsEntry("key", "value");
+	}
+
+	@Test // #1157
+	void doesNotSetSuperflousPropertiesAsMapIfSpecialContentTypeIsRequested() throws Exception {
+
+		JavaType modelType = mapper.getTypeFactory().constructParametricType(EntityModel.class, SomeSample.class);
+
+		String source = "{ \"name\" : \"Dave\", \"instrument\" : \"Guitar\" }";
+
+		EntityModel<SomeSample> result = mapper.readValue(source, modelType);
+
+		assertThat(result.getContent().name).isEqualTo("Dave");
+	}
+
 	@Relation(collectionRelation = "someSample")
 	static class SomeSample {
-		String name;
+		@JsonProperty String name;
 	}
 
 	private void verifyResolvedTitle(String resourceBundleKey) throws Exception {