DATAREST-1232 - Fix AssociationUriResolving with snake case properties

spring-data-rest-tests/spring-data-rest-tests-jpa/src/main/java/org/springframework/data/rest/webmvc/jpa/Person.java

@@ -58,6 +58,9 @@ public class Person {
 	@ManyToOne //
 	private Person father;
 
+	@ManyToOne //
+	private Person grandFather;
+
 	@Description("Timestamp this person object was created") //
 	private Date created;
 
@@ -125,6 +128,14 @@ public void setFather(Person father) {
 		this.father = father;
 	}
 
+	public Person getGrandFather() {
+		return grandFather;
+	}
+
+	public void setGrandFather(Person grandFather) {
+		this.grandFather = grandFather;
+	}
+
 	public Date getCreated() {
 		return created;
 	}

spring-data-rest-tests/spring-data-rest-tests-jpa/src/test/java/org/springframework/data/rest/webmvc/json/PersistentEntitySerializationTests.java

@@ -28,6 +28,7 @@
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.support.MessageSourceAccessor;
@@ -68,6 +69,7 @@
 import org.springframework.web.util.UriTemplate;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.PropertyNamingStrategy;
 import com.jayway.jsonpath.JsonPath;
 
 /**
@@ -85,7 +87,8 @@ public class PersistentEntitySerializationTests {
 
 	private static final String PERSON_JSON_IN = "{\"firstName\": \"John\",\"lastName\": \"Doe\"}";
 
-	@Autowired ObjectMapper mapper;
+	@Autowired @Qualifier("objectMapper") ObjectMapper mapper;
+	@Autowired @Qualifier("snakeCaseObjectMapper") ObjectMapper snakeCaseMapper;
 	@Autowired Repositories repositories;
 	@Autowired PersonRepository people;
 	@Autowired OrderRepository orders;
@@ -94,7 +97,7 @@ public class PersistentEntitySerializationTests {
 	@Configuration
 	static class TestConfig extends RepositoryTestsConfig {
 
-		@Bean
+		@Bean("objectMapper")
 		@Override
 		public ObjectMapper objectMapper() {
 
@@ -103,6 +106,16 @@ public ObjectMapper objectMapper() {
 					new JacksonSerializers(new EnumTranslator(new MessageSourceAccessor(new StaticMessageSource()))));
 			return objectMapper;
 		}
+
+		@Bean("snakeCaseObjectMapper")
+		public ObjectMapper snakeCaseObjectMapper() {
+
+			ObjectMapper objectMapper = super.objectMapper();
+			objectMapper.registerModule(
+					new JacksonSerializers(new EnumTranslator(new MessageSourceAccessor(new StaticMessageSource()))));
+			objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);
+			return objectMapper;
+		}
 	}
 
 	LinkDiscoverer linkDiscoverer;
@@ -196,6 +209,17 @@ public void deserializesEmbeddedAssociationsCorrectly() throws Exception {
 		assertThat(order.getLineItems()).hasSize(2);
 	}
 
+	@Test // DATAREST-1232
+	public void deserializesPersonWithSnakeCaseLinkToOtherPersonCorrectly() throws Exception {
+
+		Person grandFather = people.save(new Person("John", "Doe"));
+
+		String child = String.format("{ \"first_name\" : \"Bilbo\", \"grand_father\" : \"/persons/%s\"}", grandFather.getId());
+		Person result = snakeCaseMapper.readValue(child, Person.class);
+
+		assertThat(result.getGrandFather()).isEqualTo(grandFather);
+	}
+
 	@Test // DATAREST-250
 	public void serializesReferencesWithinPagedResourceCorrectly() throws Exception {
 

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/json/PersistentEntityJackson2Module.java

@@ -71,6 +71,7 @@
 import com.fasterxml.jackson.databind.JsonDeserializer;
 import com.fasterxml.jackson.databind.JsonMappingException;
 import com.fasterxml.jackson.databind.JsonSerializer;
+import com.fasterxml.jackson.databind.PropertyNamingStrategy;
 import com.fasterxml.jackson.databind.SerializationConfig;
 import com.fasterxml.jackson.databind.SerializerProvider;
 import com.fasterxml.jackson.databind.deser.BeanDeserializerBuilder;
@@ -414,6 +415,8 @@ public static class AssociationUriResolvingDeserializerModifier extends BeanDese
 		public BeanDeserializerBuilder updateBuilder(DeserializationConfig config, BeanDescription beanDesc,
 				BeanDeserializerBuilder builder) {
 
+			boolean isSnakeCase = isSnakeCaseObjectMapper(config);
+
 			Iterator<SettableBeanProperty> properties = builder.getProperties();
 
 			entities.getPersistentEntity(beanDesc.getBeanClass()).ifPresent(entity -> {
@@ -422,7 +425,7 @@ public BeanDeserializerBuilder updateBuilder(DeserializationConfig config, BeanD
 
 					SettableBeanProperty property = properties.next();
 
-					PersistentProperty<?> persistentProperty = entity.getPersistentProperty(property.getName());
+					PersistentProperty<?> persistentProperty = entity.getPersistentProperty(isSnakeCase ? toCamelCase(property.getName()) : property.getName());
 
 					if (persistentProperty == null) {
 						continue;
@@ -465,6 +468,41 @@ private static JsonDeserializer<?> wrapIfCollection(PersistentProperty<?> proper
 			CollectionValueInstantiator instantiator = new CollectionValueInstantiator(property);
 			return new CollectionDeserializer(collectionType, elementDeserializer, null, instantiator);
 		}
+
+		private static boolean isSnakeCaseObjectMapper(DeserializationConfig config) {
+
+			if (config.getPropertyNamingStrategy() == null) {
+				return false;
+			}
+
+			return config.getPropertyNamingStrategy().getClass().equals(PropertyNamingStrategy.SnakeCaseStrategy.class);
+		}
+
+		private static String toCamelCase(String value) {
+
+			if (!StringUtils.hasText(value)) {
+				return value;
+			}
+
+			if (!value.contains("_")) {
+				return value;
+			}
+
+			StringBuilder b = new StringBuilder();
+			int length = value.length();
+
+			for (int i = 0; i < length; i++) {
+				char ch = value.charAt(i);
+				if ((ch == '_') && (i < length - 1)) {
+					b.append(Character.toUpperCase(value.charAt(i + 1)));
+					i++;
+				} else if (ch != '_') {
+					b.append(ch);
+				}
+			}
+
+			return b.toString();
+		}
 	}
 
 	/**