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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/platform/basic.h"
#include "mongo/db/pipeline/document_source_sort_by_count.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/pipeline/document_source_group.h"
#include "mongo/db/pipeline/document_source_sort.h"
#include "mongo/db/pipeline/expression_context.h"
#include "mongo/db/pipeline/lite_parsed_document_source.h"
namespace mongo {
using boost::intrusive_ptr;
using std::list;
REGISTER_MULTI_STAGE_ALIAS(sortByCount,
LiteParsedDocumentSourceDefault::parse,
DocumentSourceSortByCount::createFromBson);
list<intrusive_ptr<DocumentSource>> DocumentSourceSortByCount::createFromBson(
BSONElement elem, const intrusive_ptr<ExpressionContext>& pExpCtx) {
if (elem.type() == Object) {
// Make sure that the sortByCount field is an expression inside an object
BSONObj innerObj = elem.embeddedObject();
uassert(40147,
str::stream() << "the sortByCount field must be defined as a $-prefixed path or an "
"expression inside an object",
innerObj.firstElementFieldName()[0] == '$');
} else if (elem.type() == String) {
// Make sure that the sortByCount field is a $-prefixed path
uassert(40148,
str::stream() << "the sortByCount field must be defined as a $-prefixed path or an "
"expression inside an object",
(elem.valueStringData()[0] == '$'));
} else {
uasserted(
40149,
str::stream() << "the sortByCount field must be specified as a string or as an object");
}
BSONObjBuilder groupExprBuilder;
groupExprBuilder.appendAs(elem, "_id");
groupExprBuilder.append("count", BSON("$sum" << 1));
BSONObj groupObj = BSON("$group" << groupExprBuilder.obj());
BSONObj sortObj = BSON("$sort" << BSON("count" << -1));
auto groupSource = DocumentSourceGroup::createFromBson(groupObj.firstElement(), pExpCtx);
auto sortSource = DocumentSourceSort::createFromBson(sortObj.firstElement(), pExpCtx);
return {groupSource, sortSource};
}
} // namespace mongo
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