Complete Vavr collection detection on TypeInformation and CustomConversions.

Moved Vavr collection converters into a type in the utility package. Register the converters via CustomConversions.registerConvertersIn(…) to make sure that all the Spring Data object mapping converters automatically benefit from a ConversionService that is capable of translating between Java-native collections and Vavr ones.

Issue #2511.

src/main/java/org/springframework/data/convert/CustomConversions.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2021 the original author or authors.
+ * Copyright 2011-2022 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.
@@ -16,16 +16,7 @@
 package org.springframework.data.convert;
 
 import java.lang.annotation.Annotation;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.HashSet;
-import java.util.LinkedHashSet;
-import java.util.List;
-import java.util.Map;
-import java.util.Optional;
-import java.util.Set;
+import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Function;
 import java.util.function.Predicate;
@@ -33,7 +24,6 @@ import java.util.stream.Collectors;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-
 import org.springframework.core.GenericTypeResolver;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.convert.converter.Converter;
@@ -46,6 +36,7 @@ import org.springframework.data.convert.ConverterBuilder.ConverterAware;
 import org.springframework.data.mapping.model.SimpleTypeHolder;
 import org.springframework.data.util.Predicates;
 import org.springframework.data.util.Streamable;
+import org.springframework.data.util.VavrCollectionConverters;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
@@ -178,6 +169,7 @@ public class CustomConversions {
 		Assert.notNull(conversionService, "ConversionService must not be null!");
 
 		converters.forEach(it -> registerConverterIn(it, conversionService));
+		VavrCollectionConverters.getConvertersToRegister().forEach(it -> registerConverterIn(it, conversionService));
 	}
 
 	/**

src/main/java/org/springframework/data/repository/util/QueryExecutionConverters.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2021 the original author or authors.
+ * Copyright 2014-2022 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.
@@ -43,6 +43,7 @@ import org.springframework.data.util.NullableWrapperConverters;
 import org.springframework.data.util.StreamUtils;
 import org.springframework.data.util.Streamable;
 import org.springframework.data.util.TypeInformation;
+import org.springframework.data.util.VavrCollectionConverters;
 import org.springframework.lang.Nullable;
 import org.springframework.scheduling.annotation.AsyncResult;
 import org.springframework.util.Assert;
@@ -99,7 +100,7 @@ public abstract class QueryExecutionConverters {
 
 		if (VAVR_PRESENT) {
 
-			WRAPPER_TYPES.add(VavrCollections.ToJavaConverter.INSTANCE.getWrapperType());
+			WRAPPER_TYPES.add(VavrTraversableUnwrapper.INSTANCE.getWrapperType());
 			UNWRAPPERS.add(VavrTraversableUnwrapper.INSTANCE);
 
 			// Try support
@@ -196,7 +197,7 @@ public abstract class QueryExecutionConverters {
 		NullableWrapperConverters.registerConvertersIn(conversionService);
 
 		if (VAVR_PRESENT) {
-			conversionService.addConverter(VavrCollections.FromJavaConverter.INSTANCE);
+			conversionService.addConverter(VavrCollectionConverters.FromJavaConverter.INSTANCE);
 		}
 
 		conversionService.addConverter(new NullableWrapperToCompletableFutureConverter());
@@ -408,23 +409,29 @@ public abstract class QueryExecutionConverters {
 
 		INSTANCE;
 
+		private static final TypeDescriptor OBJECT_DESCRIPTOR = TypeDescriptor.valueOf(Object.class);
+
 		/*
 		 * (non-Javadoc)
 		 * @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)
 		 */
 		@Nullable
 		@Override
-		@SuppressWarnings("unchecked")
+		@SuppressWarnings("null")
 		public Object convert(Object source) {
 
 			if (source instanceof io.vavr.collection.Traversable) {
-				return VavrCollections.ToJavaConverter.INSTANCE.convert(source);
+				return VavrCollectionConverters.ToJavaConverter.INSTANCE //
+						.convert(source, TypeDescriptor.forObject(source), OBJECT_DESCRIPTOR);
 			}
 
 			return source;
 		}
-	}
 
+		public WrapperType getWrapperType() {
+			return WrapperType.multiValue(io.vavr.collection.Traversable.class);
+		}
+	}
 
 	private static class IterableToStreamableConverter implements ConditionalGenericConverter {
 

src/main/java/org/springframework/data/util/TypeDiscoverer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2021 the original author or authors.
+ * Copyright 2011-2022 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.
@@ -25,16 +25,7 @@ import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
 import java.lang.reflect.TypeVariable;
 import java.lang.reflect.WildcardType;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Map;
-import java.util.Optional;
-import java.util.Set;
+import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.Collectors;
 
@@ -384,23 +375,10 @@ class TypeDiscoverer<S> implements TypeInformation<S> {
 
 		return rawType.isArray() //
 				|| Iterable.class.equals(rawType) //
-				|| Streamable.class.isAssignableFrom(rawType)
+				|| Streamable.class.isAssignableFrom(rawType) //
 				|| isCollection();
 	}
 
-	private boolean isCollection() {
-
-		Class<S> type = getType();
-
-		for (Class<?> collectionType : COLLECTION_TYPES) {
-			if (collectionType.isAssignableFrom(type)) {
-				return true;
-			}
-		}
-
-		return false;
-	}
-
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.util.TypeInformation#getComponentType()
@@ -427,7 +405,7 @@ class TypeDiscoverer<S> implements TypeInformation<S> {
 			return getTypeArgument(Iterable.class, 0);
 		}
 
-		if(isNullableWrapper()) {
+		if (isNullableWrapper()) {
 			return getTypeArgument(rawType, 0);
 		}
 
@@ -613,6 +591,24 @@ class TypeDiscoverer<S> implements TypeInformation<S> {
 		return hashCode;
 	}
 
+	/**
+	 * Returns whether the current type is considered a collection.
+	 *
+	 * @return
+	 */
+	private boolean isCollection() {
+
+		Class<S> type = getType();
+
+		for (Class<?> collectionType : COLLECTION_TYPES) {
+			if (collectionType.isAssignableFrom(type)) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+
 	/**
 	 * A synthetic {@link ParameterizedType}.
 	 *

src/main/java/org/springframework/data/util/VavrCollectionConverters.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2021 the original author or authors.
+ * Copyright 2022 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.
@@ -13,50 +13,91 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.springframework.data.repository.util;
+package org.springframework.data.util;
 
 import io.vavr.collection.LinkedHashMap;
 import io.vavr.collection.LinkedHashSet;
 import io.vavr.collection.Traversable;
 
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.convert.converter.ConditionalGenericConverter;
-import org.springframework.core.convert.converter.Converter;
-import org.springframework.data.repository.util.QueryExecutionConverters.WrapperType;
 import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
+import org.springframework.util.ClassUtils;
 
 /**
  * Converter implementations to map from and to Vavr collections.
  *
  * @author Oliver Gierke
  * @author Christoph Strobl
- * @since 2.0
+ * @since 2.7
  */
-class VavrCollections {
+public class VavrCollectionConverters {
 
-	public enum ToJavaConverter implements Converter<Object, Object> {
+	private static final boolean VAVR_PRESENT = ClassUtils.isPresent("io.vavr.control.Option",
+			NullableWrapperConverters.class.getClassLoader());
 
-		INSTANCE;
+	public static Collection<Object> getConvertersToRegister() {
 
-		public WrapperType getWrapperType() {
-			return WrapperType.multiValue(io.vavr.collection.Traversable.class);
+		if (!VAVR_PRESENT) {
+			return Collections.emptyList();
 		}
 
+		return Arrays.asList(ToJavaConverter.INSTANCE, FromJavaConverter.INSTANCE);
+	}
+
+	public enum ToJavaConverter implements ConditionalGenericConverter {
+
+		INSTANCE;
+
+		private static final TypeDescriptor TRAVERSAL_TYPE = TypeDescriptor.valueOf(Traversable.class);
+		private static final Set<Class<?>> COLLECTIONS_AND_MAP = new HashSet<>(
+				Arrays.asList(Collection.class, List.class, Set.class, Map.class));
+
 		/*
 		 * (non-Javadoc)
-		 * @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)
+		 * @see org.springframework.core.convert.converter.GenericConverter#getConvertibleTypes()
 		 */
 		@NonNull
 		@Override
-		public Object convert(Object source) {
+		public Set<ConvertiblePair> getConvertibleTypes() {
+
+			return COLLECTIONS_AND_MAP.stream()
+					.map(it -> new ConvertiblePair(Traversable.class, it))
+					.collect(Collectors.toSet());
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.core.convert.converter.ConditionalConverter#matches(org.springframework.core.convert.TypeDescriptor, org.springframework.core.convert.TypeDescriptor)
+		 */
+		@Override
+		public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
+
+			return sourceType.isAssignableTo(TRAVERSAL_TYPE)
+					&& COLLECTIONS_AND_MAP.contains(targetType.getType());
+		}
+
+		/*
+		 * (non-Javadoc)
+		 * @see org.springframework.core.convert.converter.GenericConverter#convert(java.lang.Object, org.springframework.core.convert.TypeDescriptor, org.springframework.core.convert.TypeDescriptor)
+		 */
+		@Nullable
+		@Override
+		public Object convert(@Nullable Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
+
+			if (source == null) {
+				return null;
+			}
 
 			if (source instanceof io.vavr.collection.Seq) {
 				return ((io.vavr.collection.Seq<?>) source).asJava();

src/test/java/org/springframework/data/convert/CustomConversionsUnitTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2021 the original author or authors.
+ * Copyright 2011-2022 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 static org.mockito.Mockito.*;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Date;
+import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.function.Predicate;
@@ -30,7 +31,6 @@ import org.jmolecules.ddd.types.Association;
 import org.jmolecules.ddd.types.Identifier;
 import org.joda.time.DateTime;
 import org.junit.jupiter.api.Test;
-
 import org.springframework.aop.framework.ProxyFactory;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.core.convert.converter.ConverterFactory;
@@ -46,7 +46,6 @@ import org.springframework.data.convert.Jsr310Converters.LocalDateTimeToDateConv
 import org.springframework.data.convert.ThreeTenBackPortConverters.LocalDateTimeToJavaTimeInstantConverter;
 import org.springframework.data.geo.Point;
 import org.springframework.data.mapping.model.SimpleTypeHolder;
-
 import org.threeten.bp.LocalDateTime;
 
 /**
@@ -292,6 +291,18 @@ class CustomConversionsUnitTests {
 		assertThat(conversions.hasCustomReadTarget(String.class, Identifier.class)).isTrue();
 	}
 
+	@Test // GH-2511
+	void registersVavrConverters() {
+
+		ConfigurableConversionService conversionService = new DefaultConversionService();
+
+		new CustomConversions(StoreConversions.NONE, Collections.emptyList())
+				.registerConvertersIn(conversionService);
+
+		assertThat(conversionService.canConvert(io.vavr.collection.List.class, List.class)).isTrue();
+		assertThat(conversionService.canConvert(List.class, io.vavr.collection.List.class)).isTrue();
+	}
+
 	private static Class<?> createProxyTypeFor(Class<?> type) {
 
 		ProxyFactory factory = new ProxyFactory();