/
document_source_bucket.cpp
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/
document_source_bucket.cpp
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/**
* Copyright (C) 2016 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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/db/pipeline/document_source_bucket.h"
#include "mongo/db/pipeline/document_source_group.h"
#include "mongo/db/pipeline/document_source_sort.h"
#include "mongo/db/pipeline/expression.h"
#include "mongo/db/pipeline/lite_parsed_document_source.h"
namespace mongo {
using boost::intrusive_ptr;
using std::vector;
REGISTER_MULTI_STAGE_ALIAS(bucket,
LiteParsedDocumentSourceDefault::parse,
DocumentSourceBucket::createFromBson);
namespace {
intrusive_ptr<ExpressionConstant> getExpressionConstant(BSONElement expressionElem,
VariablesParseState vps) {
auto expr = Expression::parseOperand(expressionElem, vps)->optimize();
return dynamic_cast<ExpressionConstant*>(expr.get());
}
} // namespace
vector<intrusive_ptr<DocumentSource>> DocumentSourceBucket::createFromBson(
BSONElement elem, const intrusive_ptr<ExpressionContext>& pExpCtx) {
uassert(40201,
str::stream() << "Argument to $bucket stage must be an object, but found type: "
<< typeName(elem.type())
<< ".",
elem.type() == BSONType::Object);
const BSONObj bucketObj = elem.embeddedObject();
BSONObjBuilder groupObjBuilder;
BSONObjBuilder switchObjBuilder;
VariablesIdGenerator idGenerator;
VariablesParseState vps(&idGenerator);
vector<Value> boundaryValues;
BSONElement groupByField;
Value defaultValue;
bool outputFieldSpecified = false;
for (auto&& argument : bucketObj) {
const auto argName = argument.fieldNameStringData();
if ("groupBy" == argName) {
groupByField = argument;
const bool groupByIsExpressionInObject = groupByField.type() == BSONType::Object &&
groupByField.embeddedObject().firstElementFieldName()[0] == '$';
const bool groupByIsPrefixedPath =
groupByField.type() == BSONType::String && groupByField.valueStringData()[0] == '$';
uassert(40202,
str::stream() << "The $bucket 'groupBy' field must be defined as a $-prefixed "
"path or an expression, but found: "
<< groupByField.toString(false, false)
<< ".",
groupByIsExpressionInObject || groupByIsPrefixedPath);
} else if ("boundaries" == argName) {
uassert(
40200,
str::stream() << "The $bucket 'boundaries' field must be an array, but found type: "
<< typeName(argument.type())
<< ".",
argument.type() == BSONType::Array);
for (auto&& boundaryElem : argument.embeddedObject()) {
auto exprConst = getExpressionConstant(boundaryElem, vps);
uassert(40191,
str::stream() << "The $bucket 'boundaries' field must be an array of "
"constant values, but found value: "
<< boundaryElem.toString(false, false)
<< ".",
exprConst);
boundaryValues.push_back(exprConst->getValue());
}
uassert(40192,
str::stream()
<< "The $bucket 'boundaries' field must have at least 2 values, but found "
<< boundaryValues.size()
<< " value(s).",
boundaryValues.size() >= 2);
// Make sure that the boundaries are unique, sorted in ascending order, and have the
// same canonical type.
for (size_t i = 1; i < boundaryValues.size(); ++i) {
Value lower = boundaryValues[i - 1];
Value upper = boundaryValues[i];
int lowerCanonicalType = canonicalizeBSONType(lower.getType());
int upperCanonicalType = canonicalizeBSONType(upper.getType());
uassert(40193,
str::stream() << "All values in the the 'boundaries' option to $bucket "
"must have the same type. Found conflicting types "
<< typeName(lower.getType())
<< " and "
<< typeName(upper.getType())
<< ".",
lowerCanonicalType == upperCanonicalType);
uassert(40194,
str::stream()
<< "The 'boundaries' option to $bucket must be sorted, but elements "
<< i - 1
<< " and "
<< i
<< " are not in ascending order ("
<< lower.toString()
<< " is not less than "
<< upper.toString()
<< ").",
pExpCtx->getValueComparator().evaluate(lower < upper));
}
} else if ("default" == argName) {
// If there is a default, make sure that it parses to a constant expression then add
// default to switch.
auto exprConst = getExpressionConstant(argument, vps);
uassert(40195,
str::stream()
<< "The $bucket 'default' field must be a constant expression, but found: "
<< argument.toString(false, false)
<< ".",
exprConst);
defaultValue = exprConst->getValue();
defaultValue.addToBsonObj(&switchObjBuilder, "default");
} else if ("output" == argName) {
outputFieldSpecified = true;
uassert(
40196,
str::stream() << "The $bucket 'output' field must be an object, but found type: "
<< typeName(argument.type())
<< ".",
argument.type() == BSONType::Object);
for (auto&& outputElem : argument.embeddedObject()) {
groupObjBuilder.append(outputElem);
}
} else {
uasserted(40197, str::stream() << "Unrecognized option to $bucket: " << argName << ".");
}
}
const bool isMissingRequiredField = groupByField.eoo() || boundaryValues.empty();
uassert(40198,
"$bucket requires 'groupBy' and 'boundaries' to be specified.",
!isMissingRequiredField);
Value lowerValue = boundaryValues.front();
Value upperValue = boundaryValues.back();
if (canonicalizeBSONType(defaultValue.getType()) ==
canonicalizeBSONType(lowerValue.getType())) {
// If the default has the same canonical type as the bucket's boundaries, then make sure the
// default is less than the lowest boundary or greater than or equal to the highest
// boundary.
const auto& valueCmp = pExpCtx->getValueComparator();
const bool hasValidDefault = valueCmp.evaluate(defaultValue < lowerValue) ||
valueCmp.evaluate(defaultValue >= upperValue);
uassert(40199,
"The $bucket 'default' field must be less than the lowest boundary or greater than "
"or equal to the highest boundary.",
hasValidDefault);
}
// Make the branches for the $switch expression.
BSONArrayBuilder branchesBuilder;
for (size_t i = 1; i < boundaryValues.size(); ++i) {
Value lower = boundaryValues[i - 1];
Value upper = boundaryValues[i];
BSONObj caseExpr =
BSON("$and" << BSON_ARRAY(BSON("$gte" << BSON_ARRAY(groupByField << lower))
<< BSON("$lt" << BSON_ARRAY(groupByField << upper))));
branchesBuilder.append(BSON("case" << caseExpr << "then" << lower));
}
// Add the $switch expression to the group BSON object.
switchObjBuilder.append("branches", branchesBuilder.arr());
groupObjBuilder.append("_id", BSON("$switch" << switchObjBuilder.obj()));
// If no output is specified, add a count field by default.
if (!outputFieldSpecified) {
groupObjBuilder.append("count", BSON("$sum" << 1));
}
BSONObj groupObj = BSON("$group" << groupObjBuilder.obj());
BSONObj sortObj = BSON("$sort" << BSON("_id" << 1));
auto groupSource = DocumentSourceGroup::createFromBson(groupObj.firstElement(), pExpCtx);
auto sortSource = DocumentSourceSort::createFromBson(sortObj.firstElement(), pExpCtx);
return {groupSource, sortSource};
}
} // namespace mongo