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/**
* Copyright (C) 2013 10gen 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/>.
*/
#include "mongo/db/ops/modifier_unset.h"
#include "mongo/base/error_codes.h"
#include "mongo/bson/mutable/document.h"
#include "mongo/db/ops/field_checker.h"
#include "mongo/db/ops/log_builder.h"
#include "mongo/db/ops/path_support.h"
namespace mongo {
struct ModifierUnset::PreparedState {
PreparedState(mutablebson::Document* targetDoc)
: doc(*targetDoc)
, idxFound(0)
, elemFound(doc.end())
, boundDollar("")
, noOp(false) {
}
// Document that is going to be changed.
mutablebson::Document& doc;
// Index in _fieldRef for which an Element exist in the document.
size_t idxFound;
// Element corresponding to _fieldRef[0.._idxFound].
mutablebson::Element elemFound;
// Value to bind to a $-positional field, if one is provided.
std::string boundDollar;
// This $set is a no-op?
bool noOp;
};
ModifierUnset::ModifierUnset()
: _fieldRef()
, _posDollar(0)
, _val() {
}
ModifierUnset::~ModifierUnset() {
}
Status ModifierUnset::init(const BSONElement& modExpr, const Options& opts) {
//
// field name analysis
//
// Break down the field name into its 'dotted' components (aka parts) and check that
// there are no empty parts.
_fieldRef.parse(modExpr.fieldName());
Status status = fieldchecker::isUpdatableLegacy(_fieldRef);
if (! status.isOK()) {
return status;
}
// If a $-positional operator was used, get the index in which it occurred
// and ensure only one occurrence.
size_t foundCount;
bool foundDollar = fieldchecker::isPositional(_fieldRef, &_posDollar, &foundCount);
if (foundDollar && foundCount > 1) {
return Status(ErrorCodes::BadValue, "too many positional($) elements found.");
}
//
// value analysis
//
// Unset takes any value, since there is no semantics attached to such value.
_val = modExpr;
return Status::OK();
}
Status ModifierUnset::prepare(mutablebson::Element root,
const StringData& matchedField,
ExecInfo* execInfo) {
_preparedState.reset(new PreparedState(&root.getDocument()));
// If we have a $-positional field, it is time to bind it to an actual field part.
if (_posDollar) {
if (matchedField.empty()) {
return Status(ErrorCodes::BadValue, "matched field not provided");
}
_preparedState->boundDollar = matchedField.toString();
_fieldRef.setPart(_posDollar, _preparedState->boundDollar);
}
// Locate the field name in 'root'. Note that if we don't have the full path in the
// doc, there isn't anything to unset, really.
Status status = pathsupport::findLongestPrefix(_fieldRef,
root,
&_preparedState->idxFound,
&_preparedState->elemFound);
if (!status.isOK() ||
_preparedState->idxFound != (_fieldRef.numParts() -1)) {
execInfo->noOp = _preparedState->noOp = true;
execInfo->fieldRef[0] = &_fieldRef;
return Status::OK();
}
// If there is indeed something to unset, we register so, along with the interest in
// the field name. The driver needs this info to sort out if there is any conflict
// among mods.
execInfo->fieldRef[0] = &_fieldRef;
// The only way for an $unset to be inplace is for its target field to be the last one
// of the object. That is, it is always the right child on its paths. The current
// rationale is that there should be no holes in a BSONObj and, to be in place, no
// field boundaries must change.
//
// TODO:
// mutablebson::Element curr = _preparedState->elemFound;
// while (curr.ok()) {
// if (curr.rightSibling().ok()) {
// }
// curr = curr.parent();
// }
return Status::OK();
}
Status ModifierUnset::apply() const {
dassert(!_preparedState->noOp);
// Our semantics says that, if we're unseting an element of an array, we swap that
// value to null. The rationale is that we don't want other array elements to change
// indices. (That could be achieved with $pull-ing element from it.)
if (_preparedState->elemFound.parent().ok() &&
_preparedState->elemFound.parent().getType() == Array) {
return _preparedState->elemFound.setValueNull();
}
else {
return _preparedState->elemFound.remove();
}
}
Status ModifierUnset::log(LogBuilder* logBuilder) const {
// We'd like to create an entry such as {$unset: {<fieldname>: 1}} under 'logRoot'.
// We start by creating the {$unset: ...} Element.
mutablebson::Document& doc = logBuilder->getDocument();
// Create the {<fieldname>: <value>} Element. Note that <fieldname> must be a
// dotted field, and not only the last part of that field. The rationale here is that
// somoene picking up this log entry -- e.g., a secondary -- must be capable of doing
// the same path find/creation that was done in the previous calls here.
mutablebson::Element logElement = doc.makeElementInt(_fieldRef.dottedField(), 1);
if (!logElement.ok()) {
return Status(ErrorCodes::InternalError, "cannot create log details for $unset mod");
}
return logBuilder->addToUnsets(logElement);
}
} // namespace mongo
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