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The MongoDB Java Driver uber-artifact, containing mongodb-driver, mongodb-driver-core, and bson
/*
* Copyright (c) 2008-2014 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 com.mongodb.operation;
import com.mongodb.MongoNamespace;
import com.mongodb.ServerAddress;
import com.mongodb.async.AsyncBatchCursor;
import com.mongodb.async.SingleResultCallback;
import com.mongodb.binding.AsyncReadBinding;
import com.mongodb.binding.ConnectionSource;
import com.mongodb.binding.ReadBinding;
import com.mongodb.connection.AsyncConnection;
import com.mongodb.connection.Connection;
import com.mongodb.connection.ConnectionDescription;
import com.mongodb.connection.QueryResult;
import com.mongodb.operation.CommandOperationHelper.CommandTransformer;
import org.bson.BsonDocument;
import org.bson.BsonJavaScript;
import org.bson.BsonString;
import org.bson.codecs.Decoder;
import static com.mongodb.assertions.Assertions.notNull;
import static com.mongodb.internal.async.ErrorHandlingResultCallback.errorHandlingCallback;
import static com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol;
import static com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocolAsync;
import static com.mongodb.operation.OperationHelper.AsyncCallableWithConnection;
import static com.mongodb.operation.OperationHelper.CallableWithConnectionAndSource;
import static com.mongodb.operation.OperationHelper.LOGGER;
import static com.mongodb.operation.OperationHelper.releasingCallback;
import static com.mongodb.operation.OperationHelper.withConnection;
/**
* Groups documents in a collection by the specified key and performs simple aggregation functions, such as computing counts and sums. The
* command is analogous to a SELECT ... GROUP BY statement in SQL.
*
* @param the operations result type.
* @mongodb.driver.manual reference/command/group Group Command
* @since 3.0
*/
public class GroupOperation implements AsyncReadOperation>, ReadOperation> {
private final MongoNamespace namespace;
private final Decoder decoder;
private final BsonJavaScript reduceFunction;
private final BsonDocument initial;
private BsonDocument key;
private BsonJavaScript keyFunction;
private BsonDocument filter;
private BsonJavaScript finalizeFunction;
/**
* Create an operation that will perform a Group on a given collection.
*
* @param namespace the database and collection namespace for the operation.
* @param reduceFunction The aggregation function that operates on the documents during the grouping operation.
* @param initial The initial the aggregation result document.
* @param decoder the decoder for the result documents.
* @mongodb.driver.manual reference/command/group Group Command
*/
public GroupOperation(final MongoNamespace namespace, final BsonJavaScript reduceFunction,
final BsonDocument initial, final Decoder decoder) {
this.namespace = notNull("namespace", namespace);
this.reduceFunction = notNull("reduceFunction", reduceFunction);
this.initial = notNull("initial", initial);
this.decoder = notNull("decoder", decoder);
}
/**
* Gets the document containing the field or fields to group.
*
* @return the document containing the field or fields to group.
*/
public BsonDocument getKey() {
return key;
}
/**
* Sets the document containing the field or fields to group.
*
* @param key the document containing the field or fields to group.
* @return this
*/
public GroupOperation key(final BsonDocument key) {
this.key = key;
return this;
}
/**
* Gets the function that creates a "key object" for use as the grouping key.
*
* @return the function that creates a "key object" for use as the grouping key.
*/
public BsonJavaScript getKeyFunction() {
return keyFunction;
}
/**
* Sets the function that creates a "key object" for use as the grouping key.
*
* @param keyFunction the function that creates a "key object" for use as the grouping key.
* @return this
*/
public GroupOperation keyFunction(final BsonJavaScript keyFunction) {
this.keyFunction = keyFunction;
return this;
}
/**
* Gets the initial the aggregation result document.
*
* @return the initial the aggregation result document.
*/
public BsonDocument getInitial() {
return initial;
}
/**
* Gets the aggregation function that operates on the documents during the grouping operation.
*
* @return the aggregation function that operates on the documents during the grouping operation.
*/
public BsonJavaScript getReduceFunction() {
return reduceFunction;
}
/**
* Gets the query filter to determine which documents in the collection to process.
*
* @return the query filter to determine which documents in the collection to process.
*/
public BsonDocument getFilter() {
return filter;
}
/**
* Sets the optional query filter to determine which documents in the collection to process.
*
* @param filter the query filter to determine which documents in the collection to process.
* @return this
*/
public GroupOperation filter(final BsonDocument filter) {
this.filter = filter;
return this;
}
/**
* Gets the function that runs each item in the result before returning the final value.
*
* @return the function that runs each item in the result set before returning the final value.
*/
public BsonJavaScript getFinalizeFunction() {
return finalizeFunction;
}
/**
* Sets the function that runs each item in the result set before returning the final value.
*
* @param finalizeFunction the function that runs each item in the result set before returning the final value.
* @return this
*/
public GroupOperation finalizeFunction(final BsonJavaScript finalizeFunction) {
this.finalizeFunction = finalizeFunction;
return this;
}
/**
* Will return a cursor of Documents containing the results of the group operation.
*
* @param binding the binding
* @return a MongoCursor of T, the results of the group operation in a form to be iterated over.
*/
@Override
public BatchCursor execute(final ReadBinding binding) {
return withConnection(binding, new CallableWithConnectionAndSource>() {
@Override
public BatchCursor call(final ConnectionSource connectionSource, final Connection connection) {
return executeWrappedCommandProtocol(binding, namespace.getDatabaseName(), getCommand(),
CommandResultDocumentCodec.create(decoder, "retval"),
connection, transformer(connectionSource, connection));
}
});
}
@Override
public void executeAsync(final AsyncReadBinding binding, final SingleResultCallback> callback) {
withConnection(binding, new AsyncCallableWithConnection() {
@Override
public void call(final AsyncConnection connection, final Throwable t) {
SingleResultCallback> errHandlingCallback = errorHandlingCallback(callback, LOGGER);
if (t != null) {
errHandlingCallback.onResult(null, t);
} else {
executeWrappedCommandProtocolAsync(binding, namespace.getDatabaseName(), getCommand(),
CommandResultDocumentCodec.create(decoder, "retval"), connection, asyncTransformer(connection),
releasingCallback(errHandlingCallback, connection));
}
}
});
}
private BsonDocument getCommand() {
BsonDocument document = new BsonDocument("ns", new BsonString(namespace.getCollectionName()));
if (getKey() != null) {
document.put("key", getKey());
} else if (getKeyFunction() != null) {
document.put("$keyf", getKeyFunction());
}
document.put("initial", getInitial());
document.put("$reduce", getReduceFunction());
if (getFinalizeFunction() != null) {
document.put("finalize", getFinalizeFunction());
}
if (getFilter() != null) {
document.put("cond", getFilter());
}
return new BsonDocument("group", document);
}
private CommandTransformer> transformer(final ConnectionSource source, final Connection connection) {
return new CommandTransformer>() {
@Override
public BatchCursor apply(final BsonDocument result, final ServerAddress serverAddress) {
return new QueryBatchCursor(createQueryResult(result, connection.getDescription()), 0, 0, decoder, source);
}
};
}
private CommandTransformer> asyncTransformer(final AsyncConnection connection) {
return new CommandTransformer>() {
@Override
public AsyncBatchCursor apply(final BsonDocument result, final ServerAddress serverAddress) {
return new AsyncQueryBatchCursor(createQueryResult(result, connection.getDescription()), 0, 0, decoder);
}
};
}
@SuppressWarnings("unchecked")
private QueryResult createQueryResult(final BsonDocument result, final ConnectionDescription description) {
return new QueryResult(namespace, BsonDocumentWrapperHelper.toList(result, "retval"), 0,
description.getServerAddress());
}
}