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/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtAddOn.JsonDb module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia. For licensing terms and
** conditions see http://qt.digia.com/licensing. For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights. These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/
#include "jsondb-object.h"
#include <QCryptographicHash>
Q_DECLARE_METATYPE(QUuid)
QT_BEGIN_NAMESPACE_JSONDB
static QUuid generateUUIDv3(const QString &uri)
{
QCryptographicHash hash(QCryptographicHash::Md5);
hash.addData(QUuid(0x6ba7b810, 0x9dad, 0x11d1, 0x80, 0xb4, 0x00, 0xc0, 0x4f, 0xd4, 0x30, 0xc8).toRfc4122());
hash.addData(uri.toUtf8());
QByteArray hashResult = hash.result();
QUuid result = QUuid::fromRfc4122(hashResult);
result.data3 &= 0x0FFF;
result.data3 |= (3 << 12);
result.data4[0] &= 0x3F;
result.data4[0] |= 0x80;
return result;
}
/*!
\class JsonDbObject
\brief The JsonDbObject class provides convenience api for constructing
object that should be persisted to QtJsonDb.
Objects that are persisted to Qt JsonDb are uniquely identified by
\l{http://en.wikipedia.org/wiki/Universally_unique_identifier}{UUID} which
value is stored inside an object in a special property \c{_uuid}. JsonDbObject
provides convenience api for generating uuid for a given object.
There are several "versions" (variations) of UUID described in the
specification, and for Qt JsonDb the two important ones are the following:
\list
\li version 3 constructs uuid from a given string (usually, uri)
\li version 4 generates a random uuid
\endlist
Uuid version 3 makes a deterministic uuid from a given string, that can be
reproduce later on, which is a very useful feature allowing to make a
unique object identifier from a user-given string. For example if one saves
file meta-data into Qt JsonDb, it might be convienient to deterministically
generate uuid from a given file path. In Qt JsonDb this is achieved by
putting the raw string data into a special \c{_id} property and constructing
uuid from the object using JsonDbObject::uuidFromObject() call.
\code
#include <jsondb-object.h>
QVariantMap object;
object.insert(QLatin1String("name"), QLatin1String("Tor"));
object.insert(QLatin1String("foo"), 42);
object.insert(QLatin1String("_uuid"), JsonDbObject::uuidFromObject(object));
JsonDbClient client;
client.create(object);
\endcode
\code
#include <jsondb-object.h>
QMap<QUuid, JsonDbObject> objectsMap;
for (int i = 0; i < 10; ++i) {
JsonDbObject object;
object.insert(QLatin1String("name"), QLatin1String("Tor"));
object.insert(QLatin1String("foo"), 42);
QUuid objectid = JsonDbObject::uuidFromObject(object);
object.setUuid(objectid);
objectsMap.insert(objectid, object);
}
JsonDbClient client;
client.create(objectsMap.values());
\endcode
*/
/*!
Constructs an empty object.
*/
JsonDbObject::JsonDbObject()
{ }
/*!
Constructs object from the given \a other QVariantMap.
*/
JsonDbObject::JsonDbObject(const QVariantMap &other)
: QVariantMap(other)
{ }
/*!
Returns uuid of an object, if present.
This is the same as retrieving a value of the \c _uuid element.
\sa setUuid()
*/
QUuid JsonDbObject::uuid() const
{
QVariant v = value(QLatin1String("_uuid"));
if (v.canConvert<QUuid>())
return v.value<QUuid>();
return QUuid(v.toString());
}
/*!
Inserts the given \a uuid into the map.
This is the same as calling \c {insert(QLatin1String("_uuid"), uuid)}.
\sa uuid(), uuidFromObject()
*/
void JsonDbObject::setUuid(const QUuid &uuid)
{
insert(QLatin1String("_uuid"), QVariant::fromValue(uuid));
}
/*!
Returns a new uuid that can be used to identify given \a object.
Note that the returned uuid might be unique on every invocation on the same
object, if the \a object doesn't have the \c{_id} property and there is no
schema.
*/
QUuid JsonDbObject::uuidFromObject(const QVariantMap &object)
{
QString idvalue = object.value(QLatin1String("_id")).toString();
if (idvalue.isNull())
return QUuid::createUuid();
return generateUUIDv3(idvalue);
}
QT_END_NAMESPACE_JSONDB
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