DATACMNS-768 - Added support for Optional as query method parameter type.

Query method parameter values of JDK 8 or Guava Optional type are now transparently unwrapped on parameter value access. ParametersParameterAccessor now unwraps them on instance creation.

src/main/java/org/springframework/data/repository/query/ParametersParameterAccessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2013 the original author or authors.
+ * Copyright 2008-2015 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.
@@ -15,10 +15,13 @@
  */
 package org.springframework.data.repository.query;
 
+import java.util.ArrayList;
 import java.util.Iterator;
+import java.util.List;
 
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Sort;
+import org.springframework.data.repository.util.QueryExecutionConverters;
 import org.springframework.util.Assert;
 
 /**
@@ -29,13 +32,13 @@ import org.springframework.util.Assert;
 public class ParametersParameterAccessor implements ParameterAccessor {
 
 	private final Parameters<?, ?> parameters;
-	private final Object[] values;
+	private final List<Object> values;
 
 	/**
 	 * Creates a new {@link ParametersParameterAccessor}.
 	 * 
-	 * @param parameters
-	 * @param values
+	 * @param parameters must not be {@literal null}.
+	 * @param values must not be {@literal null}.
 	 */
 	public ParametersParameterAccessor(Parameters<?, ?> parameters, Object[] values) {
 
@@ -45,7 +48,14 @@ public class ParametersParameterAccessor implements ParameterAccessor {
 		Assert.isTrue(parameters.getNumberOfParameters() == values.length, "Invalid number of parameters given!");
 
 		this.parameters = parameters;
-		this.values = values.clone();
+
+		List<Object> unwrapped = new ArrayList<Object>(values.length);
+
+		for (Object element : values.clone()) {
+			unwrapped.add(QueryExecutionConverters.unwrap(element));
+		}
+
+		this.values = unwrapped;
 	}
 
 	/**
@@ -67,7 +77,7 @@ public class ParametersParameterAccessor implements ParameterAccessor {
 			return null;
 		}
 
-		return (Pageable) values[parameters.getPageableIndex()];
+		return (Pageable) values.get(parameters.getPageableIndex());
 	}
 
 	/*
@@ -77,7 +87,7 @@ public class ParametersParameterAccessor implements ParameterAccessor {
 	public Sort getSort() {
 
 		if (parameters.hasSortParameter()) {
-			return (Sort) values[parameters.getSortIndex()];
+			return (Sort) values.get(parameters.getSortIndex());
 		}
 
 		if (parameters.hasPageableParameter() && getPageable() != null) {
@@ -95,7 +105,7 @@ public class ParametersParameterAccessor implements ParameterAccessor {
 	 */
 	@SuppressWarnings("unchecked")
 	protected <T> T getValue(int index) {
-		return (T) values[index];
+		return (T) values.get(index);
 	}
 
 	/*
@@ -103,8 +113,7 @@ public class ParametersParameterAccessor implements ParameterAccessor {
 	 * @see org.springframework.data.repository.query.ParameterAccessor#getBindableValue(int)
 	 */
 	public Object getBindableValue(int index) {
-
-		return values[parameters.getBindableParameter(index).getIndex()];
+		return values.get(parameters.getBindableParameter(index).getIndex());
 	}
 
 	/*
@@ -114,7 +123,7 @@ public class ParametersParameterAccessor implements ParameterAccessor {
 	public boolean hasBindableNullValue() {
 
 		for (Parameter parameter : parameters.getBindableParameters()) {
-			if (values[parameter.getIndex()] == null) {
+			if (values.get(parameter.getIndex()) == null) {
 				return true;
 			}
 		}
@@ -127,7 +136,6 @@ public class ParametersParameterAccessor implements ParameterAccessor {
 	 * @see org.springframework.data.repository.query.ParameterAccessor#iterator()
 	 */
 	public BindableParameterIterator iterator() {
-
 		return new BindableParameterIterator();
 	}
 
@@ -146,7 +154,6 @@ public class ParametersParameterAccessor implements ParameterAccessor {
 		 * @return
 		 */
 		public Object next() {
-
 			return getBindableValue(currentIndex++);
 		}
 
@@ -155,8 +162,7 @@ public class ParametersParameterAccessor implements ParameterAccessor {
 		 * @see java.util.Iterator#hasNext()
 		 */
 		public boolean hasNext() {
-
-			return values.length > currentIndex;
+			return values.size() > currentIndex;
 		}
 
 		/*
@@ -164,7 +170,6 @@ public class ParametersParameterAccessor implements ParameterAccessor {
 		 * @see java.util.Iterator#remove()
 		 */
 		public void remove() {
-
 			throw new UnsupportedOperationException();
 		}
 	}

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

@@ -52,6 +52,7 @@ public abstract class QueryExecutionConverters {
 			QueryExecutionConverters.class.getClassLoader());
 
 	private static final Set<Class<?>> WRAPPER_TYPES = new HashSet<Class<?>>();
+	private static final Set<Converter<Object, Object>> UNWRAPPERS = new HashSet<Converter<Object, Object>>();
 
 	static {
 
@@ -60,10 +61,12 @@ public abstract class QueryExecutionConverters {
 
 		if (GUAVA_PRESENT) {
 			WRAPPER_TYPES.add(NullableWrapperToGuavaOptionalConverter.getWrapperType());
+			UNWRAPPERS.add(GuavaOptionalUnwrapper.INSTANCE);
 		}
 
 		if (JDK_8_PRESENT) {
 			WRAPPER_TYPES.add(NullableWrapperToJdk8OptionalConverter.getWrapperType());
+			UNWRAPPERS.add(Jdk8OptionalUnwrapper.INSTANCE);
 		}
 
 		if (JDK_8_PRESENT && SPRING_4_2_PRESENT) {
@@ -82,7 +85,14 @@ public abstract class QueryExecutionConverters {
 	public static boolean supports(Class<?> type) {
 
 		Assert.notNull(type, "Type must not be null!");
-		return WRAPPER_TYPES.contains(type);
+
+		for (Class<?> candidate : WRAPPER_TYPES) {
+			if (candidate.isAssignableFrom(type)) {
+				return true;
+			}
+		}
+
+		return false;
 	}
 
 	/**
@@ -106,6 +116,30 @@ public abstract class QueryExecutionConverters {
 		conversionService.addConverter(new NullableWrapperToFutureConverter(conversionService));
 	}
 
+	/**
+	 * Unwraps the given source value in case it's one of the currently supported wrapper types detected at runtime.
+	 * 
+	 * @param source can be {@literal null}.
+	 * @return
+	 */
+	public static Object unwrap(Object source) {
+
+		if (source == null || !supports(source.getClass())) {
+			return source;
+		}
+
+		for (Converter<Object, Object> converter : UNWRAPPERS) {
+
+			Object result = converter.convert(source);
+
+			if (result != source) {
+				return result;
+			}
+		}
+
+		return source;
+	}
+
 	/**
 	 * Base class for converters that create instances of wrapper types such as Google Guava's and JDK 8's
 	 * {@code Optional} types.
@@ -334,4 +368,44 @@ public abstract class QueryExecutionConverters {
 			return CompletableFuture.class;
 		}
 	}
+
+	/**
+	 * A {@link Converter} to unwrap Guava {@link Optional} instances.
+	 *
+	 * @author Oliver Gierke
+	 * @since 1.12
+	 */
+	private static enum GuavaOptionalUnwrapper implements Converter<Object, Object> {
+
+		INSTANCE;
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)
+		 */
+		@Override
+		public Object convert(Object source) {
+			return source instanceof Optional ? ((Optional<?>) source).orNull() : source;
+		}
+	}
+
+	/**
+	 * A {@link Converter} to unwrap JDK 8 {@link java.util.Optional} instances.
+	 *
+	 * @author Oliver Gierke
+	 * @since 1.12
+	 */
+	private static enum Jdk8OptionalUnwrapper implements Converter<Object, Object> {
+
+		INSTANCE;
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)
+		 */
+		@Override
+		public Object convert(Object source) {
+			return source instanceof java.util.Optional ? ((java.util.Optional<?>) source).orElse(null) : source;
+		}
+	}
 }

src/test/java/org/springframework/data/repository/util/QueryExecutionConvertersUnitTests.java

@@ -109,4 +109,36 @@ public class QueryExecutionConvertersUnitTests {
 		assertThat(result.isDone(), is(true));
 		assertThat(result.get(), is(nullValue()));
 	}
+
+	/**
+	 * @see DATACMNS-768
+	 */
+	@Test
+	public void unwrapsJdk8Optional() {
+		assertThat(QueryExecutionConverters.unwrap(java.util.Optional.of("Foo")), is((Object) "Foo"));
+	}
+
+	/**
+	 * @see DATACMNS-768
+	 */
+	@Test
+	public void unwrapsGuava8Optional() {
+		assertThat(QueryExecutionConverters.unwrap(Optional.of("Foo")), is((Object) "Foo"));
+	}
+
+	/**
+	 * @see DATACMNS-768
+	 */
+	@Test
+	public void unwrapsNullToNull() {
+		assertThat(QueryExecutionConverters.unwrap(null), is(nullValue()));
+	}
+
+	/**
+	 * @see DATACMNS-768
+	 */
+	@Test
+	public void unwrapsNonWrapperTypeToItself() {
+		assertThat(QueryExecutionConverters.unwrap("Foo"), is((Object) "Foo"));
+	}
 }