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    • software.amazon.awssdk.enhanced.dynamodb.internal.converter.attribute.SetAttributeConverter Maven / Gradle / Ivy

    /*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file 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 software.amazon.awssdk.enhanced.dynamodb.internal.converter.attribute;

import static java.util.stream.Collectors.toList;

import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collectors;
import software.amazon.awssdk.annotations.Immutable;
import software.amazon.awssdk.annotations.NotThreadSafe;
import software.amazon.awssdk.annotations.SdkInternalApi;
import software.amazon.awssdk.annotations.ThreadSafe;
import software.amazon.awssdk.core.SdkBytes;
import software.amazon.awssdk.enhanced.dynamodb.AttributeConverter;
import software.amazon.awssdk.enhanced.dynamodb.AttributeValueType;
import software.amazon.awssdk.enhanced.dynamodb.EnhancedType;
import software.amazon.awssdk.enhanced.dynamodb.internal.converter.TypeConvertingVisitor;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.utils.Validate;


/**
 * A converter between a specific {@link Collection} type and {@link EnhancedAttributeValue}.
 *
 * 
    
 * This stores values in DynamoDB as a list of attribute values. This uses a configured {@link AttributeConverter} to convert
 * the collection contents to an attribute value.
 *
 * 
    
 * This supports reading a list of attribute values. This uses a configured {@link AttributeConverter} to convert
 * the collection contents.
 *
 * 
    
 * A builder is exposed to allow defining how the collection and element types are created and converted:
 * 
 * {@literal AttributeConverter> listConverter =
 * CollectionAttributeConverter.builder(EnhancedType.listOf(Integer.class))
 * .collectionConstructor(ArrayList::new)
 * .elementConverter(IntegerAttributeConverter.create())
 * .build()}
 * 
 *
 * 
    
 * For frequently-used types, static methods are exposed to reduce the amount of boilerplate involved in creation:
 * 
 * {@literal AttributeConverter> listConverter =
 * CollectionAttributeConverter.listConverter(IntegerAttributeConverter.create());}
 * 
 * 
    
 * 
 * {@literal AttributeConverter> collectionConverer =
 * CollectionAttributeConverter.collectionConverter(IntegerAttributeConverter.create());}
 * 
 * 
    
 * 
 * {@literal AttributeConverter> setConverter =
 * CollectionAttributeConverter.setConverter(IntegerAttributeConverter.create());}
 * 
 * 
    
 * 
 * {@literal AttributeConverter> sortedSetConverter =
 * CollectionAttributeConverter.sortedSetConverter(IntegerAttributeConverter.create());}
 * 
 *
 * @see MapAttributeConverter
 */
@SdkInternalApi
@ThreadSafe
@Immutable
public class SetAttributeConverter> implements AttributeConverter {
    private final Delegate delegate;

    private SetAttributeConverter(Delegate delegate) {
        this.delegate = delegate;
    }

    public static  SetAttributeConverter> setConverter(AttributeConverter elementConverter) {
        return builder(EnhancedType.setOf(elementConverter.type()))
            .collectionConstructor(LinkedHashSet::new)
            .elementConverter(elementConverter)
            .build();
    }

    public static , U> SetAttributeConverter.Builder builder(EnhancedType collectionType) {
        return new Builder<>(collectionType);
    }

    @Override
    public EnhancedType type() {
        return delegate.type();
    }

    @Override
    public AttributeValueType attributeValueType() {
        return delegate.attributeValueType();
    }

    @Override
    public AttributeValue transformFrom(T input) {
        return delegate.transformFrom(input);
    }

    @Override
    public T transformTo(AttributeValue input) {
        return delegate.transformTo(input);
    }

    private static final class Delegate, U> implements AttributeConverter {
        private final EnhancedType type;
        private final Supplier collectionConstructor;
        private final AttributeConverter elementConverter;
        private final AttributeValueType attributeValueType;

        private Delegate(Builder builder) {
            this.type = builder.collectionType;
            this.collectionConstructor = builder.collectionConstructor;
            this.elementConverter = builder.elementConverter;
            this.attributeValueType = attributeValueTypeForSet(this.elementConverter);
        }

        @Override
        public EnhancedType type() {
            return type;
        }

        @Override
        public AttributeValueType attributeValueType() {
            return attributeValueType;
        }

        @Override
        public AttributeValue transformFrom(T input) {
            return flatten(input.stream()
                                .map(elementConverter::transformFrom)
                                .collect(toList()));
        }

        @Override
        public T transformTo(AttributeValue input) {
            return EnhancedAttributeValue.fromAttributeValue(input)
                                         .convert(new TypeConvertingVisitor(type.rawClass(), SetAttributeConverter.class) {
                                             @Override
                                             public T convertSetOfStrings(List value) {
                                                 return convertCollection(value, v -> AttributeValue.builder().s(v).build());
                                             }

                                             @Override
                                             public T convertSetOfNumbers(List value) {
                                                 return convertCollection(value, v -> AttributeValue.builder().n(v).build());
                                             }

                                             @Override
                                             public T convertSetOfBytes(List value) {
                                                 return convertCollection(value, v -> AttributeValue.builder().b(v).build());
                                             }

                                             @Override
                                             public T convertListOfAttributeValues(List value) {
                                                 return convertCollection(value, Function.identity());
                                             }

                                             private  T convertCollection(Collection collection,
                                                                             Function transformFrom) {
                                                 Collection result = (Collection) collectionConstructor.get();

                                                 collection.stream()
                                                           .map(transformFrom)
                                                           .map(elementConverter::transformTo)
                                                           .forEach(result::add);

                                                 // This is a safe cast - We know the values we added to the list
                                                 // match the type that the customer requested.
                                                 return (T) result;
                                             }
                                         });
        }

        private AttributeValueType attributeValueTypeForSet(AttributeConverter innerType) {
            switch (innerType.attributeValueType()) {
                case N:
                    return AttributeValueType.NS;
                case S:
                    return AttributeValueType.SS;
                case B:
                    return AttributeValueType.BS;
                default:
                    throw new IllegalArgumentException(
                        String.format("SetAttributeConverter cannot be created with a parameterized type of '%s'. " +
                                      "Supported parameterized types must convert to B, S or N DynamoDB " +
                                      "AttributeValues.", innerType.type().rawClass()));
            }
        }

        /**
         * Takes a list of {@link AttributeValue}s and flattens into a resulting
         * single {@link AttributeValue} set of the corresponding type.
         */
        public AttributeValue flatten(List listOfAttributeValues) {
            Validate.paramNotNull(listOfAttributeValues, "listOfAttributeValues");
            Validate.noNullElements(listOfAttributeValues, "List must not have null values.");

            switch (attributeValueType) {
                case NS:
                    return AttributeValue.builder()
                                         .ns(listOfAttributeValues.stream()
                                                                  .peek(av -> Validate.isTrue(av.n() != null,
                                                                                              "Attribute value must be N."))
                                                                  .map(AttributeValue::n)
                                                                  .collect(Collectors.toList()))
                                         .build();
                case SS:
                    return AttributeValue.builder()
                                         .ss(listOfAttributeValues.stream()
                                                                  .peek(av -> Validate.isTrue(av.s() != null,
                                                                                              "Attribute value must be S."))
                                                                  .map(AttributeValue::s)
                                                                  .collect(Collectors.toList()))
                                         .build();
                case BS:
                    return AttributeValue.builder()
                                         .bs(listOfAttributeValues.stream()
                                                                  .peek(av -> Validate.isTrue(av.b() != null,
                                                                                              "Attribute value must be B."))
                                                                  .map(AttributeValue::b)
                                                                  .collect(Collectors.toList()))
                                         .build();
                default:
                    throw new IllegalStateException("Unsupported set attribute value type: " + attributeValueType);
            }
        }
    }

    @NotThreadSafe
    public static final class Builder, U> {
        private final EnhancedType collectionType;
        private Supplier collectionConstructor;
        private AttributeConverter elementConverter;

        private Builder(EnhancedType collectionType) {
            this.collectionType = collectionType;
        }

        public Builder collectionConstructor(Supplier collectionConstructor) {
            this.collectionConstructor = collectionConstructor;
            return this;
        }

        public Builder elementConverter(AttributeConverter elementConverter) {
            this.elementConverter = elementConverter;
            return this;
        }

        public SetAttributeConverter build() {
            return new SetAttributeConverter<>(new Delegate<>(this));
        }
    }
}
    
    
    
    

    




    
    
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