/*
 * Copyright 2008-present MongoDB, Inc.
 *
 * 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
 *
 *   http://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.bson.codecs;

import org.bson.BsonDocument;
import org.bson.BsonDocumentWriter;
import org.bson.BsonReader;
import org.bson.BsonType;
import org.bson.BsonValue;
import org.bson.BsonWriter;
import org.bson.Document;
import org.bson.Transformer;
import org.bson.UuidRepresentation;
import org.bson.codecs.configuration.CodecRegistry;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.UUID;

import static java.util.Arrays.asList;
import static org.bson.assertions.Assertions.notNull;
import static org.bson.codecs.configuration.CodecRegistries.fromProviders;

A Codec for Document instances.
See Also:
  • Document
Since:3.0
/** * A Codec for Document instances. * * @see org.bson.Document * @since 3.0 */
public class DocumentCodec implements CollectibleCodec<Document>, OverridableUuidRepresentationCodec<Document> { private static final String ID_FIELD_NAME = "_id"; private static final CodecRegistry DEFAULT_REGISTRY = fromProviders(asList(new ValueCodecProvider(), new BsonValueCodecProvider(), new DocumentCodecProvider())); private static final BsonTypeClassMap DEFAULT_BSON_TYPE_CLASS_MAP = new BsonTypeClassMap(); private final BsonTypeCodecMap bsonTypeCodecMap; private final CodecRegistry registry; private final IdGenerator idGenerator; private final Transformer valueTransformer; private final UuidRepresentation uuidRepresentation;
Construct a new instance with a default CodecRegistry.
/** * Construct a new instance with a default {@code CodecRegistry}. */
public DocumentCodec() { this(DEFAULT_REGISTRY); }
Construct a new instance with the given registry.
Params:
  • registry – the registry
Since:3.5
/** * Construct a new instance with the given registry. * * @param registry the registry * @since 3.5 */
public DocumentCodec(final CodecRegistry registry) { this(registry, DEFAULT_BSON_TYPE_CLASS_MAP); }
Construct a new instance with the given registry and BSON type class map.
Params:
  • registry – the registry
  • bsonTypeClassMap – the BSON type class map
/** * Construct a new instance with the given registry and BSON type class map. * * @param registry the registry * @param bsonTypeClassMap the BSON type class map */
public DocumentCodec(final CodecRegistry registry, final BsonTypeClassMap bsonTypeClassMap) { this(registry, bsonTypeClassMap, null); }
Construct a new instance with the given registry and BSON type class map. The transformer is applied as a last step when decoding values, which allows users of this codec to control the decoding process. For example, a user of this class could substitute a value decoded as a Document with an instance of a special purpose class (e.g., one representing a DBRef in MongoDB).
Params:
  • registry – the registry
  • bsonTypeClassMap – the BSON type class map
  • valueTransformer – the value transformer to use as a final step when decoding the value of any field in the document
/** * Construct a new instance with the given registry and BSON type class map. The transformer is applied as a last step when decoding * values, which allows users of this codec to control the decoding process. For example, a user of this class could substitute a * value decoded as a Document with an instance of a special purpose class (e.g., one representing a DBRef in MongoDB). * * @param registry the registry * @param bsonTypeClassMap the BSON type class map * @param valueTransformer the value transformer to use as a final step when decoding the value of any field in the document */
public DocumentCodec(final CodecRegistry registry, final BsonTypeClassMap bsonTypeClassMap, final Transformer valueTransformer) { this(registry, new BsonTypeCodecMap(notNull("bsonTypeClassMap", bsonTypeClassMap), registry), new ObjectIdGenerator(), valueTransformer, UuidRepresentation.JAVA_LEGACY); } private DocumentCodec(final CodecRegistry registry, final BsonTypeCodecMap bsonTypeCodecMap, final IdGenerator idGenerator, final Transformer valueTransformer, final UuidRepresentation uuidRepresentation) { this.registry = notNull("registry", registry); this.bsonTypeCodecMap = bsonTypeCodecMap; this.idGenerator = idGenerator; this.valueTransformer = valueTransformer != null ? valueTransformer : new Transformer() { @Override public Object transform(final Object value) { return value; } }; this.uuidRepresentation = uuidRepresentation; } @Override public Codec<Document> withUuidRepresentation(final UuidRepresentation uuidRepresentation) { return new DocumentCodec(registry, bsonTypeCodecMap, idGenerator, valueTransformer, uuidRepresentation); } @Override public boolean documentHasId(final Document document) { return document.containsKey(ID_FIELD_NAME); } @Override public BsonValue getDocumentId(final Document document) { if (!documentHasId(document)) { throw new IllegalStateException("The document does not contain an _id"); } Object id = document.get(ID_FIELD_NAME); if (id instanceof BsonValue) { return (BsonValue) id; } BsonDocument idHoldingDocument = new BsonDocument(); BsonWriter writer = new BsonDocumentWriter(idHoldingDocument); writer.writeStartDocument(); writer.writeName(ID_FIELD_NAME); writeValue(writer, EncoderContext.builder().build(), id); writer.writeEndDocument(); return idHoldingDocument.get(ID_FIELD_NAME); } @Override public Document generateIdIfAbsentFromDocument(final Document document) { if (!documentHasId(document)) { document.put(ID_FIELD_NAME, idGenerator.generate()); } return document; } @Override public void encode(final BsonWriter writer, final Document document, final EncoderContext encoderContext) { writeMap(writer, document, encoderContext); } @Override public Document decode(final BsonReader reader, final DecoderContext decoderContext) { Document document = new Document(); reader.readStartDocument(); while (reader.readBsonType() != BsonType.END_OF_DOCUMENT) { String fieldName = reader.readName(); document.put(fieldName, readValue(reader, decoderContext)); } reader.readEndDocument(); return document; } @Override public Class<Document> getEncoderClass() { return Document.class; } private void beforeFields(final BsonWriter bsonWriter, final EncoderContext encoderContext, final Map<String, Object> document) { if (encoderContext.isEncodingCollectibleDocument() && document.containsKey(ID_FIELD_NAME)) { bsonWriter.writeName(ID_FIELD_NAME); writeValue(bsonWriter, encoderContext, document.get(ID_FIELD_NAME)); } } private boolean skipField(final EncoderContext encoderContext, final String key) { return encoderContext.isEncodingCollectibleDocument() && key.equals(ID_FIELD_NAME); } @SuppressWarnings({"unchecked", "rawtypes"}) private void writeValue(final BsonWriter writer, final EncoderContext encoderContext, final Object value) { if (value == null) { writer.writeNull(); } else if (value instanceof Iterable) { writeIterable(writer, (Iterable<Object>) value, encoderContext.getChildContext()); } else if (value instanceof Map) { writeMap(writer, (Map<String, Object>) value, encoderContext.getChildContext()); } else { Codec codec = registry.get(value.getClass()); encoderContext.encodeWithChildContext(codec, writer, value); } } private void writeMap(final BsonWriter writer, final Map<String, Object> map, final EncoderContext encoderContext) { writer.writeStartDocument(); beforeFields(writer, encoderContext, map); for (final Map.Entry<String, Object> entry : map.entrySet()) { if (skipField(encoderContext, entry.getKey())) { continue; } writer.writeName(entry.getKey()); writeValue(writer, encoderContext, entry.getValue()); } writer.writeEndDocument(); } private void writeIterable(final BsonWriter writer, final Iterable<Object> list, final EncoderContext encoderContext) { writer.writeStartArray(); for (final Object value : list) { writeValue(writer, encoderContext, value); } writer.writeEndArray(); } private Object readValue(final BsonReader reader, final DecoderContext decoderContext) { BsonType bsonType = reader.getCurrentBsonType(); if (bsonType == BsonType.NULL) { reader.readNull(); return null; } else if (bsonType == BsonType.ARRAY) { return readList(reader, decoderContext); } else { Codec<?> codec = bsonTypeCodecMap.get(bsonType); if (bsonType == BsonType.BINARY && reader.peekBinarySize() == 16) { switch (reader.peekBinarySubType()) { case 3: if (uuidRepresentation == UuidRepresentation.JAVA_LEGACY || uuidRepresentation == UuidRepresentation.C_SHARP_LEGACY || uuidRepresentation == UuidRepresentation.PYTHON_LEGACY) { codec = registry.get(UUID.class); } break; case 4: if (uuidRepresentation == UuidRepresentation.JAVA_LEGACY || uuidRepresentation == UuidRepresentation.STANDARD) { codec = registry.get(UUID.class); } break; default: break; } } return valueTransformer.transform(codec.decode(reader, decoderContext)); } } private List<Object> readList(final BsonReader reader, final DecoderContext decoderContext) { reader.readStartArray(); List<Object> list = new ArrayList<Object>(); while (reader.readBsonType() != BsonType.END_OF_DOCUMENT) { list.add(readValue(reader, decoderContext)); } reader.readEndArray(); return list; } }