Next stage.

src/main/java/org/springframework/data/neo4j/core/convert/ConvertWith.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2011-2020 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.neo4j.core.convert;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+import java.util.function.Function;
+
+import org.apiguardian.api.API;
+import org.neo4j.driver.Value;
+
+/**
+ * This annotation can be used to define either custom conversions for single attributes by specifying both a writing
+ * and a reading converter class and if needed, a custom factory for those or it can be used to build custom meta-annotated
+ * annotations like {@code @org.springframework.data.neo4j.core.support.DateLong}.
+ *
+ * <p>Custom conversions are applied to both attributes of entities and parameters of repository methods that map to those
+ * attributes (which does apply to all derived queries and queries by example but not to string based queries).
+ *
+ * <p>Converter functions that have a default constructor don't need a dedicated factory. A dedicated factory will
+ * be provided with either this annotation and its values or with the meta annotated annotation, including all configuration
+ * available.
+ *
+ * @author Michael J. Simons
+ * @soundtrack Antilopen Gang - Abwasser
+ * @since 6.0
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ ElementType.ANNOTATION_TYPE, ElementType.FIELD })
+@Inherited
+@Documented
+@API(status = API.Status.STABLE, since = "6.0")
+public @interface ConvertWith {
+
+	Class<? extends Function<?, Value>> writingConverter() default WritingPlaceholder.class;
+
+	Class<? extends Function<Value, ?>> readingConverter() default ReadingPlaceholder.class;
+
+	Class<? extends CustomConversionFactory> converterFactory() default DefaultCustomConversionFactory.class;
+
+	/**
+	 * Indicates an unset writing converter.
+	 */
+	final class WritingPlaceholder implements Function<Object, Value> {
+
+		@Override
+		public Value apply(Object o) {
+			throw new UnsupportedOperationException();
+		}
+	}
+
+	/**
+	 * Indicates an unset reading converter.
+	 */
+	final class ReadingPlaceholder implements Function<Value, Object> {
+
+		@Override
+		public Object apply(Value value) {
+			throw new UnsupportedOperationException();
+		}
+	}
+}

src/main/java/org/springframework/data/neo4j/core/convert/CustomConversion.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2011-2020 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.neo4j.core.convert;
+
+import java.util.Objects;
+import java.util.function.Function;
+
+import org.apiguardian.api.API;
+import org.neo4j.driver.Value;
+import org.springframework.util.Assert;
+
+/**
+ * This class presents the pair of writing and reading converters for a custom conversion. Bot directions are required.
+ *
+ * @author Michael J. Simons
+ * @soundtrack Antilopen Gang - Adrenochrom
+ * @since 6.0
+ */
+@API(status = API.Status.STABLE, since = "6.0")
+public final class CustomConversion {
+
+	private final Function<?, Value> writingConverter;
+
+	private final Function<Value, ?> readingConverter;
+
+	public CustomConversion(Function<?, Value> writingConverter, Function<Value, ?> readingConverter) {
+
+		Assert.notNull(writingConverter, "A writing converter is required.");
+		this.writingConverter = writingConverter;
+		Assert.notNull(readingConverter, "A reading converter is required.");
+		this.readingConverter = readingConverter;
+	}
+
+	public Function<?, Value> getWritingConverter() {
+		return writingConverter;
+	}
+
+	public Function<Value, ?> getReadingConverter() {
+		return readingConverter;
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o) {
+			return true;
+		}
+		if (o == null || getClass() != o.getClass()) {
+			return false;
+		}
+		CustomConversion that = (CustomConversion) o;
+		return writingConverter.equals(that.writingConverter) &&
+				readingConverter.equals(that.readingConverter);
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(writingConverter, readingConverter);
+	}
+}

src/main/java/org/springframework/data/neo4j/core/convert/CustomConversionFactory.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2011-2020 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.neo4j.core.convert;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.AnnotatedElement;
+
+import org.springframework.core.annotation.MergedAnnotation;
+import org.springframework.core.annotation.MergedAnnotations;
+import org.springframework.util.ReflectionUtils;
+
+/**
+ * This interface needs to be implemented to provide custom configuration for a {@link CustomConversion}. Use cases may
+ * be specific date formats or the like. The build method will receive the whole annotation, including all attributes.
+ * Classes implementing this interface <strong>must</strong> have a default constructor.
+ *
+ * @param <A> The type of the annotation
+ * @author Michael J. Simons
+ * @soundtrack Antilopen Gang - Abwasser
+ * @since 6.0
+ */
+public interface CustomConversionFactory<A extends Annotation> {
+
+	/**
+	 * @param config The configuration for building the custom conversion
+	 * @return The actual conversion
+	 */
+	CustomConversion buildConversion(A config, Class<?> typeOfAnnotatedElement);
+}

src/main/java/org/springframework/data/neo4j/core/convert/DefaultCustomConversionFactory.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2011-2020 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.neo4j.core.convert;
+
+import java.util.function.Function;
+
+import org.neo4j.driver.Value;
+import org.springframework.beans.BeanUtils;
+
+/**
+ * @author Michael J. Simons
+ * @soundtrack Metallica - S&M2
+ * @since 6.0
+ */
+final class DefaultCustomConversionFactory implements CustomConversionFactory<ConvertWith> {
+
+	@Override
+	public CustomConversion buildConversion(ConvertWith config, Class<?> typeOfAnnotatedElement) {
+
+		if (config.writingConverter() == ConvertWith.WritingPlaceholder.class) {
+			throw new IllegalArgumentException("The default custom conversion factory cannot be used with a placeholder");
+		}
+
+		if (config.readingConverter() == ConvertWith.ReadingPlaceholder.class) {
+			throw new IllegalArgumentException("The default custom conversion factory cannot be used with a placeholder");
+		}
+
+		Function<?, Value> writingConverter = BeanUtils.instantiateClass(config.writingConverter());
+		Function<Value, ?> readingConverter = BeanUtils.instantiateClass(config.readingConverter());
+		return new CustomConversion(writingConverter, readingConverter);
+	}
+}

src/main/java/org/springframework/data/neo4j/core/mapping/DefaultNeo4jPersistentProperty.java

@@ -15,12 +15,13 @@
  */
 package org.springframework.data.neo4j.core.mapping;
 
+import java.lang.annotation.Annotation;
 import java.util.Optional;
 import java.util.function.Function;
 
 import org.neo4j.driver.Value;
-import org.springframework.beans.BeanUtils;
-import org.springframework.core.convert.converter.Converter;
+import org.springframework.core.annotation.MergedAnnotation;
+import org.springframework.core.annotation.MergedAnnotations;
 import org.springframework.data.mapping.Association;
 import org.springframework.data.mapping.MappingException;
 import org.springframework.data.mapping.PersistentEntity;
@@ -30,11 +31,14 @@
 import org.springframework.data.neo4j.core.schema.Relationship;
 import org.springframework.data.neo4j.core.schema.RelationshipProperties;
 import org.springframework.data.neo4j.core.schema.TargetNode;
-import org.springframework.data.neo4j.core.support.ConvertAs;
+import org.springframework.data.neo4j.core.convert.ConvertWith;
+import org.springframework.data.neo4j.core.convert.CustomConversionFactory;
+import org.springframework.data.neo4j.core.convert.CustomConversion;
 import org.springframework.data.util.Lazy;
 import org.springframework.data.util.TypeInformation;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.ReflectionUtils;
 
 /**
  * @author Michael J. Simons
@@ -49,42 +53,39 @@ final class DefaultNeo4jPersistentProperty extends AnnotationBasedPersistentProp
 
 	private final Neo4jMappingContext mappingContext;
 
-	private final Lazy<Function<Object, Value>> writingConverter;
-	private final Lazy<Function<Value, Object>> readingConverter;
+	private final Lazy<CustomConversion> customConversion;
 
 	/**
 	 * Creates a new {@link AnnotationBasedPersistentProperty}.
 	 *
-	 * @param property must not be {@literal null}.
-	 * @param owner must not be {@literal null}.
+	 * @param property         must not be {@literal null}.
+	 * @param owner            must not be {@literal null}.
 	 * @param simpleTypeHolder type holder
 	 */
 	DefaultNeo4jPersistentProperty(Property property, PersistentEntity<?, Neo4jPersistentProperty> owner,
-			Neo4jMappingContext mappingContext, SimpleTypeHolder simpleTypeHolder, boolean isEntityInRelationshipWithProperties) {
+			Neo4jMappingContext mappingContext, SimpleTypeHolder simpleTypeHolder,
+			boolean isEntityInRelationshipWithProperties) {
 
 		super(property, owner, simpleTypeHolder);
 		this.isEntityInRelationshipWithProperties = isEntityInRelationshipWithProperties;
+		this.mappingContext = mappingContext;
 
 		this.graphPropertyName = Lazy.of(this::computeGraphPropertyName);
 		this.isAssociation = Lazy.of(() -> {
 
 			Class<?> targetType = getActualType();
-			return !(simpleTypeHolder.isSimpleType(targetType) || mappingContext.hasCustomWriteTarget(targetType) || isAnnotationPresent(TargetNode.class));
+			return !(simpleTypeHolder.isSimpleType(targetType) || this.mappingContext.hasCustomWriteTarget(targetType)
+					|| isAnnotationPresent(TargetNode.class));
 		});
-		// TODO Configuration of converters needs to be accounted for.
-		this.writingConverter = Lazy.of(() -> {
 
-			ConvertAs annotation = findAnnotation(ConvertAs.class);
-			return annotation == null ? null :
-					(Function<Object, Value>) BeanUtils.instantiateClass(annotation.writingConverter());
-		});
-		this.readingConverter = Lazy.of(() -> {
+		this.customConversion = Lazy.of(() -> {
+
+			if(this.isEntity()) {
+				return null;
+			}
 
-			ConvertAs annotation = findAnnotation(ConvertAs.class);
-			return annotation == null ? null :
-					(Function<Value, Object>) BeanUtils.instantiateClass(annotation.readingConverter());
+			return this.mappingContext.getOptionalCustomConversionsFor(getRequiredField(), getActualType());
 		});
-		this.mappingContext = mappingContext;
 	}
 
 	@Override
@@ -166,11 +167,12 @@ public boolean isEntity() {
 
 	@Override
 	public Function<Object, Value> getOptionalWritingConverter() {
-		return isEntity() ? null : writingConverter.getNullable();
+		return (Function<Object, Value>) customConversion.getOptional().map(CustomConversion::getWritingConverter).orElse(null);
 	}
 
+	@Override
 	public Function<Value, Object> getOptionalReadingConverter() {
-		return isEntity() ? null : readingConverter.getNullable();
+		return (Function<Value, Object>) customConversion.getOptional().map(CustomConversion::getReadingConverter).orElse(null);
 	}
 
 	@Override