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DATACMNS-795 - Added support for Scala's Option type on repositories.

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Just like with Google's or Java 8's optional we now support Scala's Option type as wrapper fro return values on repositories.
This commit is contained in:
Oliver Gierke
2015-12-16 18:02:42 +01:00
parent 4af7fe3165
commit 306795468d
4 changed files with 113 additions and 58 deletions
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131
src/main/java/org/springframework/data/repository/util/QueryExecutionConverters.java
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@@ -15,6 +15,8 @@
*/
package org.springframework.data.repository.util;
import scala.Option;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
@@ -35,7 +37,15 @@ import com.google.common.base.Optional;
/**
* Converters to potentially wrap the execution of a repository method into a variety of wrapper types potentially being
* available on the classpath.
* available on the classpath. Currently supported:
* <ul>
* <li>{@code java.util.Optional}</li>
* <li>{@code com.google.common.base.Optional}</li>
* <li>{@code scala.Option}</li>
* <li>{@code java.util.concurrent.Future}</li>
* <li>{@code java.util.concurrent.CompletableFuture}</li>
* <li>{@code org.springframework.util.concurrent.ListenableFuture<}</li>
* </ul>
*
* @author Oliver Gierke
* @since 1.8
@@ -50,6 +60,8 @@ public abstract class QueryExecutionConverters {
QueryExecutionConverters.class.getClassLoader());
private static final boolean JDK_8_PRESENT = ClassUtils.isPresent("java.util.Optional",
QueryExecutionConverters.class.getClassLoader());
private static final boolean SCALA_PRESENT = ClassUtils.isPresent("scala.Option",
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>>();
@@ -72,6 +84,11 @@ public abstract class QueryExecutionConverters {
if (JDK_8_PRESENT && SPRING_4_2_PRESENT) {
WRAPPER_TYPES.add(NullableWrapperToCompletableFutureConverter.getWrapperType());
}
if (SCALA_PRESENT) {
WRAPPER_TYPES.add(NullableWrapperToScalaOptionConverter.getWrapperType());
UNWRAPPERS.add(ScalOptionUnwrapper.INSTANCE);
}
}
private QueryExecutionConverters() {}
@@ -113,6 +130,10 @@ public abstract class QueryExecutionConverters {
conversionService.addConverter(new NullableWrapperToCompletableFutureConverter(conversionService));
}
if (SCALA_PRESENT) {
conversionService.addConverter(new NullableWrapperToScalaOptionConverter(conversionService));
}
conversionService.addConverter(new NullableWrapperToFutureConverter(conversionService));
}
@@ -151,6 +172,7 @@ public abstract class QueryExecutionConverters {
@SuppressWarnings("unused") //
private final ConversionService conversionService;
private final Class<?>[] wrapperTypes;
private final Object nullValue;
/**
* Creates a new {@link AbstractWrapperTypeConverter} using the given {@link ConversionService} and wrapper type.
@@ -158,13 +180,15 @@ public abstract class QueryExecutionConverters {
* @param conversionService must not be {@literal null}.
* @param wrapperTypes must not be {@literal null}.
*/
protected AbstractWrapperTypeConverter(ConversionService conversionService, Class<?>... wrapperTypes) {
protected AbstractWrapperTypeConverter(ConversionService conversionService, Object nullValue,
Class<?>... wrapperTypes) {
Assert.notNull(conversionService, "ConversionService must not be null!");
Assert.notEmpty(wrapperTypes, "Wrapper type must not be empty!");
this.conversionService = conversionService;
this.wrapperTypes = wrapperTypes;
this.nullValue = nullValue;
}
/*
@@ -194,16 +218,9 @@ public abstract class QueryExecutionConverters {
Object value = wrapper.getValue();
// TODO: Add Recursive conversion once we move to Spring 4
return value == null ? getNullValue() : wrap(value);
return value == null ? nullValue : wrap(value);
}
/**
* Return the object that shall be used as a replacement for {@literal null}.
*
* @return must not be {@literal null}.
*/
protected abstract Object getNullValue();
/**
* Wrap the given, non-{@literal null} value into the wrapper type.
*
@@ -226,16 +243,7 @@ public abstract class QueryExecutionConverters {
* @param conversionService must not be {@literal null}.
*/
public NullableWrapperToGuavaOptionalConverter(ConversionService conversionService) {
super(conversionService, Optional.class);
}
/*
* (non-Javadoc)
* @see org.springframework.data.repository.util.QueryExecutionConverters.AbstractWrapperTypeConverter#getNullValue()
*/
@Override
protected Object getNullValue() {
return Optional.absent();
super(conversionService, Optional.absent(), Optional.class);
}
/*
@@ -265,16 +273,7 @@ public abstract class QueryExecutionConverters {
* @param conversionService must not be {@literal null}.
*/
public NullableWrapperToJdk8OptionalConverter(ConversionService conversionService) {
super(conversionService, java.util.Optional.class);
}
/*
* (non-Javadoc)
* @see org.springframework.data.repository.util.QueryExecutionConverters.AbstractWrapperTypeConverter#getNullValue()
*/
@Override
protected Object getNullValue() {
return java.util.Optional.empty();
super(conversionService, java.util.Optional.empty(), java.util.Optional.class);
}
/*
@@ -298,24 +297,13 @@ public abstract class QueryExecutionConverters {
*/
private static class NullableWrapperToFutureConverter extends AbstractWrapperTypeConverter {
private static final AsyncResult<Object> NULL_OBJECT = new AsyncResult<Object>(null);
/**
* Creates a new {@link NullableWrapperToFutureConverter} using the given {@link ConversionService}.
*
* @param conversionService must not be {@literal null}.
*/
public NullableWrapperToFutureConverter(ConversionService conversionService) {
super(conversionService, Future.class, ListenableFuture.class);
}
/*
* (non-Javadoc)
* @see org.springframework.data.repository.util.QueryExecutionConverters.AbstractWrapperTypeConverter#getNullValue()
*/
@Override
protected Object getNullValue() {
return NULL_OBJECT;
super(conversionService, new AsyncResult<Object>(null), Future.class, ListenableFuture.class);
}
/*
@@ -335,24 +323,13 @@ public abstract class QueryExecutionConverters {
*/
private static class NullableWrapperToCompletableFutureConverter extends AbstractWrapperTypeConverter {
private static final CompletableFuture<Object> NULL_OBJECT = CompletableFuture.completedFuture(null);
/**
* Creates a new {@link NullableWrapperToCompletableFutureConverter} using the given {@link ConversionService}.
*
* @param conversionService must not be {@literal null}.
*/
public NullableWrapperToCompletableFutureConverter(ConversionService conversionService) {
super(conversionService, CompletableFuture.class);
}
/*
* (non-Javadoc)
* @see org.springframework.data.repository.util.QueryExecutionConverters.AbstractWrapperTypeConverter#getNullValue()
*/
@Override
protected Object getNullValue() {
return NULL_OBJECT;
super(conversionService, CompletableFuture.completedFuture(null), CompletableFuture.class);
}
/*
@@ -369,6 +346,32 @@ public abstract class QueryExecutionConverters {
}
}
/**
* A Spring {@link Converter} to support Scala's {@link Option}.
*
* @author Oliver Gierke
* @since 1.13
*/
private static class NullableWrapperToScalaOptionConverter extends AbstractWrapperTypeConverter {
public NullableWrapperToScalaOptionConverter(ConversionService conversionService) {
super(conversionService, Option.empty(), Option.class);
}
/*
* (non-Javadoc)
* @see org.springframework.data.repository.util.QueryExecutionConverters.AbstractWrapperTypeConverter#wrap(java.lang.Object)
*/
@Override
protected Object wrap(Object source) {
return Option.apply(source);
}
public static Class<?> getWrapperType() {
return Option.class;
}
}
/**
* A {@link Converter} to unwrap Guava {@link Optional} instances.
*
@@ -408,4 +411,24 @@ public abstract class QueryExecutionConverters {
return source instanceof java.util.Optional ? ((java.util.Optional<?>) source).orElse(null) : source;
}
}
/**
* A {@link Converter} to unwrap a Scala {@link Option} instance.
*
* @author Oliver Gierke
* @author 1.13
*/
private static enum ScalOptionUnwrapper 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 Option ? ((Option<?>) source).orNull(null) : source;
}
}
}