void ParsedExclusionProjection::parse(const boost::intrusive_ptr<ExpressionContext>& expCtx,
const BSONObj& spec,
ExclusionNode* node,
size_t depth) {
for (auto elem : spec) {
const auto fieldName = elem.fieldNameStringData().toString();
// A $ should have been detected in ParsedAggregationProjection's parsing before we get
// here.
invariant(fieldName[0] != '$');
switch (elem.type()) {
case BSONType::Bool:
case BSONType::NumberInt:
case BSONType::NumberLong:
case BSONType::NumberDouble:
case BSONType::NumberDecimal: {
// We have already verified this is an exclusion projection.
invariant(!elem.trueValue());
node->excludePath(FieldPath(fieldName));
break;
}
case BSONType::Object: {
// This object represents a nested projection specification, like the sub-object in
// {a: {b: 0, c: 0}} or {"a.b": {c: 0}}.
ExclusionNode* child;
if (elem.fieldNameStringData().find('.') == std::string::npos) {
child = node->addOrGetChild(fieldName);
} else {
// A dotted field is not allowed in a sub-object, and should have been detected
// in ParsedAggregationProjection's parsing before we get here.
invariant(depth == 0);
// We need to keep adding children to our tree until we create a child that
// represents this dotted path.
child = node;
auto fullPath = FieldPath(fieldName);
while (fullPath.getPathLength() > 1) {
child = child->addOrGetChild(fullPath.getFieldName(0));
fullPath = fullPath.tail();
}
// It is illegal to construct an empty FieldPath, so the above loop ends one
// iteration too soon. Add the last path here.
child = child->addOrGetChild(fullPath.fullPath());
}
parse(expCtx, elem.Obj(), child, depth + 1);
break;
}
default: { MONGO_UNREACHABLE; }
}
}
}
void ProjectionSpecValidator::validate() {
if (_rawObj.isEmpty()) {
uasserted(40177, "specification must have at least one field");
}
for (auto&& elem : _rawObj) {
parseElement(elem, FieldPath(elem.fieldName()));
}
}
intrusive_ptr<DocumentSource> DocumentSourceUnwind::createFromBson(
BSONElement *pBsonElement,
const intrusive_ptr<ExpressionContext> &pExpCtx) {
/*
The value of $unwind should just be a field path.
*/
uassert(15981, str::stream() << "the " << unwindName <<
" field path must be specified as a string",
pBsonElement->type() == String);
string prefixedPathString(pBsonElement->str());
string pathString(Expression::removeFieldPrefix(prefixedPathString));
intrusive_ptr<DocumentSourceUnwind> pUnwind(new DocumentSourceUnwind(pExpCtx));
pUnwind->unwindPath(FieldPath(pathString));
return pUnwind;
}
void ParsedExclusionProjection::parse(const BSONObj& spec, ExclusionNode* node, size_t depth) {
bool idSpecified = false;
for (auto elem : spec) {
const auto fieldName = elem.fieldNameStringData();
// A $ should have been detected by ParsedAggregationProjection before we get here.
invariant(fieldName[0] != '$');
// Track whether the projection spec specifies a desired behavior for the _id field.
idSpecified = idSpecified || fieldName == "_id"_sd || fieldName.startsWith("_id."_sd);
switch (elem.type()) {
case BSONType::Bool:
case BSONType::NumberInt:
case BSONType::NumberLong:
case BSONType::NumberDouble:
case BSONType::NumberDecimal: {
// We have already verified this is an exclusion projection. _id is the only field
// which is permitted to be explicitly included here.
invariant(!elem.trueValue() || elem.fieldNameStringData() == "_id"_sd);
if (!elem.trueValue()) {
node->addProjectionForPath(FieldPath(fieldName));
}
break;
}
case BSONType::Object: {
// This object represents a nested projection specification, like the sub-object in
// {a: {b: 0, c: 0}} or {"a.b": {c: 0}}.
ExclusionNode* child;
if (elem.fieldNameStringData().find('.') == std::string::npos) {
child = node->addOrGetChild(fieldName.toString());
} else {
// A dotted field is not allowed in a sub-object, and should have been detected
// in ParsedAggregationProjection's parsing before we get here.
invariant(depth == 0);
// We need to keep adding children to our tree until we create a child that
// represents this dotted path.
child = node;
auto fullPath = FieldPath(fieldName);
while (fullPath.getPathLength() > 1) {
child = child->addOrGetChild(fullPath.getFieldName(0).toString());
fullPath = fullPath.tail();
}
// It is illegal to construct an empty FieldPath, so the above loop ends one
// iteration too soon. Add the last path here.
child = child->addOrGetChild(fullPath.fullPath());
}
parse(elem.Obj(), child, depth + 1);
break;
}
default: { MONGO_UNREACHABLE; }
}
}
// If _id was not specified, then doing nothing will cause it to be included. If the default _id
// policy is kExcludeId, we add a new entry for _id to the ExclusionNode tree here.
if (!idSpecified && _policies.idPolicy == ProjectionPolicies::DefaultIdPolicy::kExcludeId) {
_root->addProjectionForPath({FieldPath("_id")});
}
}