Cursor class is used to combine query and getmore requests

MongoDB/include/Poco/MongoDB/Cursor.h

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+//
+// Cursor.h
+//
+// $Id$
+//
+// Library: MongoDB
+// Package: MongoDB
+// Module:  Cursor
+//
+// Definition of the Cursor class.
+//
+// Copyright (c) 2012, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// Permission is hereby granted, free of charge, to any person or organization
+// obtaining a copy of the software and accompanying documentation covered by
+// this license (the "Software") to use, reproduce, display, distribute,
+// execute, and transmit the Software, and to prepare derivative works of the
+// Software, and to permit third-parties to whom the Software is furnished to
+// do so, all subject to the following:
+//
+// The copyright notices in the Software and this entire statement, including
+// the above license grant, this restriction and the following disclaimer,
+// must be included in all copies of the Software, in whole or in part, and
+// all derivative works of the Software, unless such copies or derivative
+// works are solely in the form of machine-executable object code generated by
+// a source language processor.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+//
+#ifndef _MongoDB_Cursor_included
+#define _MongoDB_Cursor_included
+
+#include "Poco/MongoDB/MongoDB.h"
+#include "Poco/MongoDB/Connection.h"
+#include "Poco/MongoDB/QueryRequest.h"
+#include "Poco/MongoDB/ResponseMessage.h"
+
+namespace Poco {
+namespace MongoDB {
+
+
+class MongoDB_API Cursor : public Document
+	/// Cursor is an helper class for querying multiple documents
+{
+public:
+	Cursor(const std::string& dbname, const std::string& collectionName, QueryRequest::Flags flags = QueryRequest::QUERY_NONE);
+		/// Constructor
+
+
+	Cursor(const std::string& fullCollectionName, QueryRequest::Flags flags = QueryRequest::QUERY_NONE);
+		/// Constructor
+
+
+	virtual ~Cursor();
+		/// Destructor
+
+
+	ResponseMessage& next(Connection& connection);
+		/// Try to get the next documents. As long as ResponseMessage has a
+		/// cursor id next can be called to retrieve the next bunch of documents.
+		/// kill must be called when not all documents are needed.
+
+
+	QueryRequest& query();
+		/// Returns the associated query
+
+
+	void kill(Connection& connection);
+		/// Kills the cursor and reset it so that it can be reused.
+
+
+private:
+
+
+	QueryRequest _query;
+
+
+	ResponseMessage _response;
+};
+
+
+inline QueryRequest& Cursor::query()
+{
+	return _query;
+}
+
+
+}} // Namespace Poco::MongoDB
+
+#endif //_MongoDB_Cursor_included

MongoDB/src/Cursor.cpp

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+//
+// Cursor.cpp
+//
+// $Id$
+//
+// Library: MongoDB
+// Package: MongoDB
+// Module:  Cursor
+//
+// Implementation of the Cursor class.
+//
+// Copyright (c) 2012, Applied Informatics Software Engineering GmbH.
+// and Contributors.
+//
+// Permission is hereby granted, free of charge, to any person or organization
+// obtaining a copy of the software and accompanying documentation covered by
+// this license (the "Software") to use, reproduce, display, distribute,
+// execute, and transmit the Software, and to prepare derivative works of the
+// Software, and to permit third-parties to whom the Software is furnished to
+// do so, all subject to the following:
+//
+// The copyright notices in the Software and this entire statement, including
+// the above license grant, this restriction and the following disclaimer,
+// must be included in all copies of the Software, in whole or in part, and
+// all derivative works of the Software, unless such copies or derivative
+// works are solely in the form of machine-executable object code generated by
+// a source language processor.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+//
+
+#include "Poco/MongoDB/Cursor.h"
+#include "Poco/MongoDB/GetMoreRequest.h"
+#include "Poco/MongoDB/KillCursorsRequest.h"
+
+namespace Poco
+{
+namespace MongoDB
+{
+
+
+Cursor::Cursor(const std::string& db, const std::string& collection, QueryRequest::Flags flags)
+	: _query(db + '.' + collection, flags)
+{
+}
+
+
+Cursor::Cursor(const std::string& fullCollectionName, QueryRequest::Flags flags)
+	: _query(fullCollectionName, flags)
+{
+}
+
+
+Cursor::~Cursor()
+{
+	poco_assert_dbg(_response.cursorID());
+}
+
+
+ResponseMessage& Cursor::next(Connection& connection)
+{
+	if ( _response.cursorID() == 0 )
+	{
+		connection.sendRequest(_query, _response);
+	}
+	else
+	{
+		Poco::MongoDB::GetMoreRequest getMore(_query.fullCollectionName(), _response.cursorID());
+		getMore.setNumberToReturn(_query.getNumberToReturn());
+		_response.clear();
+		connection.sendRequest(getMore, _response);
+	}
+	return _response;
+}
+
+
+void Cursor::kill(Connection& connection)
+{
+	if ( _response.cursorID() != 0 )
+	{
+		KillCursorsRequest killRequest;
+		killRequest.cursors().push_back(_response.cursorID());
+		connection.sendRequest(killRequest);
+	}
+	_response.clear();
+}
+
+} } // Namespace Poco::MongoDB
+