Refactor Locator filter settings saving

Unify setting saving. Do not write settings that stay at the default, so
defaults could change and take effect.

For this we explicitly differentiate between default and user settings.
Make QJsonDocument the basis for saving settings, because QDataStream
cannot really handle structured data where parts could be missing.

Write locator settings to a different settings group, so we do not
destroy reading older settings from older Qt Creator versions.

Task-number: QTCREATORBUG-24762
Change-Id: I5909e2d79313f6fc26159bb644fdfb43781b6c38
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/bookmarks/bookmarkfilter.cpp

@@ -40,7 +40,7 @@ BookmarkFilter::BookmarkFilter(BookmarkManager *manager)
     setId("Bookmarks");
     setDisplayName(tr("Bookmarks"));
     setPriority(Medium);
-    setShortcutString("b");
+    setDefaultShortcutString("b");
 }
 
 void BookmarkFilter::prepareSearch(const QString &entry)

src/plugins/clangcodemodel/clangcurrentdocumentfilter.cpp

@@ -56,9 +56,9 @@ ClangCurrentDocumentFilter::ClangCurrentDocumentFilter()
 {
     setId(CppTools::Constants::CURRENT_DOCUMENT_FILTER_ID);
     setDisplayName(CppTools::Constants::CURRENT_DOCUMENT_FILTER_DISPLAY_NAME);
-    setShortcutString(QString(QLatin1Char('.')));
+    setDefaultShortcutString(".");
     setPriority(High);
-    setIncludedByDefault(false);
+    setDefaultIncludedByDefault(false);
 
     Core::EditorManager *editorManager = Core::EditorManager::instance();
     connect(editorManager, &Core::EditorManager::currentEditorChanged,

src/plugins/clangrefactoring/locatorfilter.h

@@ -49,8 +49,8 @@ public:
     {
         setId(id);
         setDisplayName(displayName);
-        setShortcutString(shortCut);
-        setIncludedByDefault(includedByDefault);
+        setDefaultShortcutString(shortCut);
+        setDefaultIncludedByDefault(includedByDefault);
     }
 
     QList<Core::LocatorFilterEntry> matchesFor(QFutureInterface<Core::LocatorFilterEntry> &future,

src/plugins/cmakeprojectmanager/cmakelocatorfilter.cpp

@@ -121,7 +121,7 @@ BuildCMakeTargetLocatorFilter::BuildCMakeTargetLocatorFilter()
 {
     setId("Build CMake target");
     setDisplayName(tr("Build CMake target"));
-    setShortcutString("cm");
+    setDefaultShortcutString("cm");
     setPriority(High);
 }
 
@@ -170,7 +170,7 @@ OpenCMakeTargetLocatorFilter::OpenCMakeTargetLocatorFilter()
 {
     setId("Open CMake target definition");
     setDisplayName(tr("Open CMake target"));
-    setShortcutString("cmo");
+    setDefaultShortcutString("cmo");
     setPriority(Medium);
 }
 

src/plugins/coreplugin/locator/commandlocator.cpp

@@ -57,7 +57,7 @@ CommandLocator::CommandLocator(Id id,
 {
     setId(id);
     setDisplayName(displayName);
-    setShortcutString(shortCutString);
+    setDefaultShortcutString(shortCutString);
 }
 
 CommandLocator::~CommandLocator()

src/plugins/coreplugin/locator/directoryfilter.cpp

@@ -33,6 +33,8 @@
 #include <utils/filesearch.h>
 
 #include <QFileDialog>
+#include <QJsonArray>
+#include <QJsonObject>
 
 using namespace Utils;
 
@@ -44,61 +46,102 @@ namespace Core {
     \internal
 */
 
-DirectoryFilter::DirectoryFilter(Id id)
-    : m_filters({"*.h", "*.cpp", "*.ui", "*.qrc"}),
-      m_exclusionFilters({"*/.git/*", "*/.cvs/*", "*/.svn/*"})
+const char kDisplayNameKey[] = "displayName";
+const char kDirectoriesKey[] = "directories";
+const char kFiltersKey[] = "filters";
+const char kFilesKey[] = "files";
+const char kExclusionFiltersKey[] = "exclusionFilters";
+
+const QStringList kFiltersDefault = {"*.h", "*.cpp", "*.ui", "*.qrc"};
+const QStringList kExclusionFiltersDefault = {"*/.git/*", "*/.cvs/*", "*/.svn/*"};
+
+static QString defaultDisplayName()
 {
-    setId(id);
-    setIncludedByDefault(true);
-    setDisplayName(tr("Generic Directory Filter"));
+    return DirectoryFilter::tr("Generic Directory Filter");
 }
 
-QByteArray DirectoryFilter::saveState() const
+DirectoryFilter::DirectoryFilter(Id id)
+    : m_filters(kFiltersDefault)
+    , m_exclusionFilters(kExclusionFiltersDefault)
+{
+    setId(id);
+    setDefaultIncludedByDefault(true);
+    setDisplayName(defaultDisplayName());
+}
+
+void DirectoryFilter::saveState(QJsonObject &object) const
+{
+    QMutexLocker locker(&m_lock); // m_files is modified in other thread
+
+    if (displayName() != defaultDisplayName())
+        object.insert(kDisplayNameKey, displayName());
+    if (!m_directories.isEmpty())
+        object.insert(kDirectoriesKey, QJsonArray::fromStringList(m_directories));
+    if (m_filters != kFiltersDefault)
+        object.insert(kFiltersKey, QJsonArray::fromStringList(m_filters));
+    if (!m_files.isEmpty())
+        object.insert(kFilesKey,
+                      QJsonArray::fromStringList(
+                          Utils::transform(m_files, &Utils::FilePath::toString)));
+    if (m_exclusionFilters != kExclusionFiltersDefault)
+        object.insert(kExclusionFiltersKey, QJsonArray::fromStringList(m_exclusionFilters));
+}
+
+static QStringList toStringList(const QJsonArray &array)
+{
+    return Utils::transform(array.toVariantList(), &QVariant::toString);
+}
+
+void DirectoryFilter::restoreState(const QJsonObject &object)
 {
     QMutexLocker locker(&m_lock);
-    QByteArray value;
-    QDataStream out(&value, QIODevice::WriteOnly);
-    out << displayName();
-    out << m_directories;
-    out << m_filters;
-    out << shortcutString();
-    out << isIncludedByDefault();
-    out << Utils::transform(m_files, &Utils::FilePath::toString);
-    out << m_exclusionFilters;
-    return value;
+    setDisplayName(object.value(kDisplayNameKey).toString(defaultDisplayName()));
+    m_directories = toStringList(object.value(kDirectoriesKey).toArray());
+    m_filters = toStringList(
+        object.value(kFiltersKey).toArray(QJsonArray::fromStringList(kFiltersDefault)));
+    m_files = Utils::transform(toStringList(object.value(kFilesKey).toArray()),
+                               &FilePath::fromString);
+    m_exclusionFilters = toStringList(
+        object.value(kExclusionFiltersKey)
+            .toArray(QJsonArray::fromStringList(kExclusionFiltersDefault)));
 }
 
 void DirectoryFilter::restoreState(const QByteArray &state)
 {
-    QMutexLocker locker(&m_lock);
+    if (isOldSetting(state)) {
+        // TODO read old settings, remove some time after Qt Creator 4.15
+        QMutexLocker locker(&m_lock);
 
-    QString name;
-    QStringList directories;
-    QString shortcut;
-    bool defaultFilter;
-    QStringList files;
+        QString name;
+        QStringList directories;
+        QString shortcut;
+        bool defaultFilter;
+        QStringList files;
 
-    QDataStream in(state);
-    in >> name;
-    in >> directories;
-    in >> m_filters;
-    in >> shortcut;
-    in >> defaultFilter;
-    in >> files;
-    m_files = Utils::transform(files, &Utils::FilePath::fromString);
-    if (!in.atEnd()) // Qt Creator 4.3 and later
-        in >> m_exclusionFilters;
-    else
-        m_exclusionFilters.clear();
+        QDataStream in(state);
+        in >> name;
+        in >> directories;
+        in >> m_filters;
+        in >> shortcut;
+        in >> defaultFilter;
+        in >> files;
+        m_files = Utils::transform(files, &Utils::FilePath::fromString);
+        if (!in.atEnd()) // Qt Creator 4.3 and later
+            in >> m_exclusionFilters;
+        else
+            m_exclusionFilters.clear();
 
-    if (m_isCustomFilter)
-        m_directories = directories;
-    setDisplayName(name);
-    setShortcutString(shortcut);
-    setIncludedByDefault(defaultFilter);
+        if (m_isCustomFilter)
+            m_directories = directories;
+        setDisplayName(name);
+        setShortcutString(shortcut);
+        setIncludedByDefault(defaultFilter);
 
-    locker.unlock();
-    updateFileIterator();
+        locker.unlock();
+        updateFileIterator();
+    } else {
+        ILocatorFilter::restoreState(state);
+    }
 }
 
 bool DirectoryFilter::openConfigDialog(QWidget *parent, bool &needsRefresh)

src/plugins/coreplugin/locator/directoryfilter.h

@@ -47,7 +47,6 @@ class CORE_EXPORT DirectoryFilter : public BaseFileFilter
 
 public:
     DirectoryFilter(Utils::Id id);
-    QByteArray saveState() const override;
     void restoreState(const QByteArray &state) override;
     bool openConfigDialog(QWidget *parent, bool &needsRefresh) override;
     void refresh(QFutureInterface<void> &future) override;
@@ -60,7 +59,9 @@ public:
     void setFilters(const QStringList &filters);
     void setExclusionFilters(const QStringList &exclusionFilters);
 
-    using ILocatorFilter::setDisplayName;
+protected:
+    void saveState(QJsonObject &object) const final;
+    void restoreState(const QJsonObject &object) final;
 
 private:
     void handleAddDirectory();

src/plugins/coreplugin/locator/executefilter.cpp

@@ -38,9 +38,9 @@ ExecuteFilter::ExecuteFilter()
 {
     setId("Execute custom commands");
     setDisplayName(tr("Execute Custom Commands"));
-    setShortcutString("!");
+    setDefaultShortcutString("!");
     setPriority(High);
-    setIncludedByDefault(false);
+    setDefaultIncludedByDefault(false);
 
     m_process = new Utils::QtcProcess(this);
     m_process->setEnvironment(Utils::Environment::systemEnvironment());

src/plugins/coreplugin/locator/externaltoolsfilter.cpp

@@ -37,7 +37,7 @@ ExternalToolsFilter::ExternalToolsFilter()
 {
     setId("Run external tool");
     setDisplayName(tr("Run External Tool"));
-    setShortcutString("x");
+    setDefaultShortcutString("x");
     setPriority(Medium);
 }
 

src/plugins/coreplugin/locator/filesystemfilter.cpp

@@ -38,6 +38,7 @@
 #include <utils/fileutils.h>
 
 #include <QDir>
+#include <QJsonObject>
 #include <QPushButton>
 #include <QRegularExpression>
 
@@ -65,8 +66,8 @@ FileSystemFilter::FileSystemFilter()
 {
     setId("Files in file system");
     setDisplayName(tr("Files in File System"));
-    setShortcutString("f");
-    setIncludedByDefault(false);
+    setDefaultShortcutString("f");
+    setDefaultIncludedByDefault(false);
 }
 
 void FileSystemFilter::prepareSearch(const QString &entry)
@@ -235,28 +236,36 @@ bool FileSystemFilter::openConfigDialog(QWidget *parent, bool &needsRefresh)
     return false;
 }
 
-QByteArray FileSystemFilter::saveState() const
+const char kIncludeHiddenKey[] = "includeHidden";
+
+void FileSystemFilter::saveState(QJsonObject &object) const
 {
-    QByteArray value;
-    QDataStream out(&value, QIODevice::WriteOnly);
-    out << m_includeHidden;
-    out << shortcutString();
-    out << isIncludedByDefault();
-    return value;
+    if (m_includeHidden != kIncludeHiddenDefault)
+        object.insert(kIncludeHiddenKey, m_includeHidden);
+}
+
+void FileSystemFilter::restoreState(const QJsonObject &object)
+{
+    m_currentIncludeHidden = object.value(kIncludeHiddenKey).toBool(kIncludeHiddenDefault);
 }
 
 void FileSystemFilter::restoreState(const QByteArray &state)
 {
-    QDataStream in(state);
-    in >> m_includeHidden;
+    if (isOldSetting(state)) {
+        // TODO read old settings, remove some time after Qt Creator 4.15
+        QDataStream in(state);
+        in >> m_includeHidden;
 
-    // An attempt to prevent setting this on old configuration
-    if (!in.atEnd()) {
-        QString shortcut;
-        bool defaultFilter;
-        in >> shortcut;
-        in >> defaultFilter;
-        setShortcutString(shortcut);
-        setIncludedByDefault(defaultFilter);
+        // An attempt to prevent setting this on old configuration
+        if (!in.atEnd()) {
+            QString shortcut;
+            bool defaultFilter;
+            in >> shortcut;
+            in >> defaultFilter;
+            setShortcutString(shortcut);
+            setIncludedByDefault(defaultFilter);
+        }
+    } else {
+        ILocatorFilter::restoreState(state);
     }
 }

src/plugins/coreplugin/locator/filesystemfilter.h

@@ -47,16 +47,20 @@ public:
                                          const QString &entry) override;
     void accept(LocatorFilterEntry selection,
                 QString *newText, int *selectionStart, int *selectionLength) const override;
-    QByteArray saveState() const override;
     void restoreState(const QByteArray &state) override;
     bool openConfigDialog(QWidget *parent, bool &needsRefresh) override;
     void refresh(QFutureInterface<void> &) override {}
 
+protected:
+    void saveState(QJsonObject &object) const final;
+    void restoreState(const QJsonObject &object) final;
+
 private:
     static MatchLevel matchLevelFor(const QRegularExpressionMatch &match, const QString &matchText);
 
-    bool m_includeHidden = true;
-    bool m_currentIncludeHidden = true;
+    static const bool kIncludeHiddenDefault = true;
+    bool m_includeHidden = kIncludeHiddenDefault;
+    bool m_currentIncludeHidden = kIncludeHiddenDefault;
     QString m_currentDocumentDirectory;
 };
 

src/plugins/coreplugin/locator/ilocatorfilter.cpp

@@ -33,6 +33,8 @@
 #include <QCoreApplication>
 #include <QDialog>
 #include <QDialogButtonBox>
+#include <QJsonDocument>
+#include <QJsonObject>
 #include <QLabel>
 #include <QLineEdit>
 #include <QRegularExpression>
@@ -117,32 +119,55 @@ void ILocatorFilter::prepareSearch(const QString &entry)
 }
 
 /*!
-    Sets the \a shortcut string that can be used to explicitly choose this
-    filter in the locator input field. Call from the constructor of subclasses
-    to set the default setting.
+    Sets the default \a shortcut string that can be used to explicitly choose
+    this filter in the locator input field. Call for example from the
+    constructor of subclasses.
 
     \sa shortcutString()
 */
+void ILocatorFilter::setDefaultShortcutString(const QString &shortcut)
+{
+    m_defaultShortcut = shortcut;
+    m_shortcut = shortcut;
+}
+
+/*!
+    Sets the current shortcut string of the filter to \a shortcut. Use
+    setDefaultShortcutString() if you want to set the default shortcut string
+    instead.
+
+    \sa setDefaultShortcutString()
+*/
 void ILocatorFilter::setShortcutString(const QString &shortcut)
 {
     m_shortcut = shortcut;
 }
 
+const char kShortcutStringKey[] = "shortcut";
+const char kIncludedByDefaultKey[] = "includeByDefault";
+
 /*!
     Returns data that can be used to restore the settings for this filter
     (for example at startup).
     By default, adds the base settings (shortcut string, included by default)
-    with a data stream.
+    and calls saveState() with a JSON object where subclasses should write
+    their custom settings.
 
     \sa restoreState()
 */
 QByteArray ILocatorFilter::saveState() const
 {
-    QByteArray value;
-    QDataStream out(&value, QIODevice::WriteOnly);
-    out << shortcutString();
-    out << isIncludedByDefault();
-    return value;
+    QJsonObject obj;
+    if (shortcutString() != m_defaultShortcut)
+        obj.insert(kShortcutStringKey, shortcutString());
+    if (isIncludedByDefault() != m_defaultIncludedByDefault)
+        obj.insert(kIncludedByDefaultKey, isIncludedByDefault());
+    saveState(obj);
+    if (obj.isEmpty())
+        return {};
+    QJsonDocument doc;
+    doc.setObject(obj);
+    return doc.toJson(QJsonDocument::Compact);
 }
 
 /*!
@@ -153,15 +178,22 @@ QByteArray ILocatorFilter::saveState() const
 */
 void ILocatorFilter::restoreState(const QByteArray &state)
 {
-    QString shortcut;
-    bool defaultFilter;
+    QJsonDocument doc = QJsonDocument::fromJson(state);
+    if (state.isEmpty() || doc.isObject()) {
+        const QJsonObject obj = doc.object();
+        setShortcutString(obj.value(kShortcutStringKey).toString(m_defaultShortcut));
+        setIncludedByDefault(obj.value(kIncludedByDefaultKey).toBool(m_defaultIncludedByDefault));
+        restoreState(obj);
+    } else {
+        // TODO read old settings, remove some time after Qt Creator 4.15
+        m_shortcut = m_defaultShortcut;
+        m_includedByDefault = m_defaultIncludedByDefault;
 
-    QDataStream in(state);
-    in >> shortcut;
-    in >> defaultFilter;
-
-    setShortcutString(shortcut);
-    setIncludedByDefault(defaultFilter);
+        // TODO this reads legacy settings from Qt Creator < 4.15
+        QDataStream in(state);
+        in >> m_shortcut;
+        in >> m_includedByDefault;
+    }
 }
 
 /*!
@@ -281,13 +313,26 @@ bool ILocatorFilter::isIncludedByDefault() const
 }
 
 /*!
-    Sets whether using the shortcut string is required to use this filter
-    to \a includedByDefault.
+    Sets the default setting for whether using the shortcut string is required
+    to use this filter to \a includedByDefault.
 
-    Call from the constructor of subclasses to change the default.
+    Call for example from the constructor of subclasses.
 
     \sa isIncludedByDefault()
 */
+void ILocatorFilter::setDefaultIncludedByDefault(bool includedByDefault)
+{
+    m_defaultIncludedByDefault = includedByDefault;
+    m_includedByDefault = includedByDefault;
+}
+
+/*!
+    Sets whether using the shortcut string is required to use this filter to
+    \a includedByDefault. Use setDefaultIncludedByDefault() if you want to
+    set the default value instead.
+
+    \sa setDefaultIncludedByDefault()
+*/
 void ILocatorFilter::setIncludedByDefault(bool includedByDefault)
 {
     m_includedByDefault = includedByDefault;
@@ -402,7 +447,8 @@ void ILocatorFilter::setPriority(Priority priority)
 }
 
 /*!
-    Sets the translated display name of this filter to \a displayString.
+    Sets the translated display name of this filter to \a
+    displayString.
 
     Subclasses must set the display name in their constructor.
 
@@ -474,6 +520,44 @@ bool ILocatorFilter::openConfigDialog(QWidget *parent, QWidget *additionalWidget
     return accepted;
 }
 
+/*!
+    Saves the filter settings and state to the JSON \a object.
+
+    The default implementation does nothing.
+
+    Implementations should write key-value pairs to the \a object for their
+    custom settings that changed from the default. Default values should
+    never be saved.
+*/
+void ILocatorFilter::saveState(QJsonObject &object) const
+{
+    Q_UNUSED(object)
+}
+
+/*!
+    Reads the filter settings and state from the JSON \a object
+
+    The default implementation does nothing.
+
+    Implementations should read their custom settings from the \a object,
+    resetting any missing setting to its default value.
+*/
+void ILocatorFilter::restoreState(const QJsonObject &object)
+{
+    Q_UNUSED(object)
+}
+
+/*!
+    Returns if \a state must be restored via pre-4.15 settings reading.
+*/
+bool ILocatorFilter::isOldSetting(const QByteArray &state)
+{
+    if (state.isEmpty())
+        return false;
+    const QJsonDocument doc = QJsonDocument::fromJson(state);
+    return !doc.isObject();
+}
+
 /*!
     \fn QList<Core::LocatorFilterEntry> Core::ILocatorFilter::matchesFor(QFutureInterface<Core::LocatorFilterEntry> &future, const QString &entry)
 

src/plugins/coreplugin/locator/ilocatorfilter.h

@@ -125,10 +125,12 @@ public:
     Utils::Id actionId() const;
 
     QString displayName() const;
+    void setDisplayName(const QString &displayString);
 
     Priority priority() const;
 
     QString shortcutString() const;
+    void setDefaultShortcutString(const QString &shortcut);
     void setShortcutString(const QString &shortcut);
 
     virtual void prepareSearch(const QString &entry);
@@ -147,6 +149,7 @@ public:
     bool isConfigurable() const;
 
     bool isIncludedByDefault() const;
+    void setDefaultIncludedByDefault(bool includedByDefault);
     void setIncludedByDefault(bool includedByDefault);
 
     bool isHidden() const;
@@ -172,16 +175,22 @@ protected:
     void setHidden(bool hidden);
     void setId(Utils::Id id);
     void setPriority(Priority priority);
-    void setDisplayName(const QString &displayString);
     void setConfigurable(bool configurable);
     bool openConfigDialog(QWidget *parent, QWidget *additionalWidget);
 
+    virtual void saveState(QJsonObject &object) const;
+    virtual void restoreState(const QJsonObject &object);
+
+    static bool isOldSetting(const QByteArray &state);
+
 private:
     Utils::Id m_id;
     QString m_shortcut;
     Priority m_priority = Medium;
     QString m_displayName;
-    bool m_includedByDefault = false;
+    QString m_defaultShortcut;
+    bool m_defaultIncludedByDefault = false;
+    bool m_includedByDefault = m_defaultIncludedByDefault;
     bool m_hidden = false;
     bool m_enabled = true;
     bool m_isConfigurable = true;

src/plugins/coreplugin/locator/javascriptfilter.cpp

@@ -38,8 +38,8 @@ JavaScriptFilter::JavaScriptFilter()
 {
     setId("JavaScriptFilter");
     setDisplayName(tr("Evaluate JavaScript"));
-    setIncludedByDefault(false);
-    setShortcutString("=");
+    setDefaultIncludedByDefault(false);
+    setDefaultShortcutString("=");
     m_abortTimer.setSingleShot(true);
     m_abortTimer.setInterval(1000);
     connect(&m_abortTimer, &QTimer::timeout, this, [this] {

src/plugins/coreplugin/locator/locator.cpp

@@ -92,7 +92,7 @@ public:
 
 LocatorData::LocatorData()
 {
-    m_urlFilter.setShortcutString("r");
+    m_urlFilter.setDefaultShortcutString("r");
     m_urlFilter.addDefaultUrl("https://www.bing.com/search?q=%1");
     m_urlFilter.addDefaultUrl("https://www.google.com/search?q=%1");
     m_urlFilter.addDefaultUrl("https://search.yahoo.com/search?p=%1");
@@ -101,7 +101,7 @@ LocatorData::LocatorData()
         "http://en.cppreference.com/mwiki/index.php?title=Special%3ASearch&search=%1");
     m_urlFilter.addDefaultUrl("https://en.wikipedia.org/w/index.php?search=%1");
 
-    m_bugFilter.setShortcutString("bug");
+    m_bugFilter.setDefaultShortcutString("bug");
     m_bugFilter.addDefaultUrl("https://bugreports.qt.io/secure/QuickSearch.jspa?searchString=%1");
 }
 
@@ -172,7 +172,11 @@ bool Locator::delayedInitialize()
 void Locator::loadSettings()
 {
     SettingsDatabase *settings = ICore::settingsDatabase();
-    settings->beginGroup("QuickOpen");
+    // check if we have to read old settings
+    // TOOD remove a few versions after 4.15
+    const QString settingsGroup = settings->contains("Locator") ? QString("Locator")
+                                                                : QString("QuickOpen");
+    settings->beginGroup(settingsGroup);
     m_refreshTimer.setInterval(settings->value("RefreshInterval", 60).toInt() * 60000);
 
     for (ILocatorFilter *filter : qAsConst(m_filters)) {
@@ -297,12 +301,14 @@ void Locator::saveSettings() const
 
     SettingsDatabase *s = ICore::settingsDatabase();
     s->beginTransaction();
-    s->beginGroup("QuickOpen");
+    s->beginGroup("Locator");
     s->remove(QString());
     s->setValue("RefreshInterval", refreshInterval());
     for (ILocatorFilter *filter : m_filters) {
-        if (!m_customFilters.contains(filter))
-            s->setValue(filter->id().toString(), filter->saveState());
+        if (!m_customFilters.contains(filter)) {
+            const QByteArray state = filter->saveState();
+            s->setValueWithDefault(filter->id().toString(), state);
+        }
     }
     s->beginGroup("CustomFilters");
     int i = 0;
@@ -311,7 +317,8 @@ void Locator::saveSettings() const
                                  Constants::CUSTOM_DIRECTORY_FILTER_BASEID)
                                  ? kDirectoryFilterPrefix
                                  : kUrlFilterPrefix;
-        s->setValue(prefix + QString::number(i), filter->saveState());
+        const QByteArray state = filter->saveState();
+        s->setValueWithDefault(prefix + QString::number(i), state);
         ++i;
     }
     s->endGroup();

src/plugins/coreplugin/locator/locatorfiltersfilter.cpp

@@ -41,7 +41,7 @@ LocatorFiltersFilter::LocatorFiltersFilter():
 {
     setId("FiltersFilter");
     setDisplayName(tr("Available filters"));
-    setIncludedByDefault(true);
+    setDefaultIncludedByDefault(true);
     setHidden(true);
     setPriority(Highest);
     setConfigurable(false);

src/plugins/coreplugin/locator/opendocumentsfilter.cpp

@@ -42,9 +42,9 @@ OpenDocumentsFilter::OpenDocumentsFilter()
 {
     setId("Open documents");
     setDisplayName(tr("Open Documents"));
-    setShortcutString("o");
+    setDefaultShortcutString("o");
     setPriority(High);
-    setIncludedByDefault(true);
+    setDefaultIncludedByDefault(true);
 
     connect(DocumentModel::model(), &QAbstractItemModel::dataChanged,
             this, &OpenDocumentsFilter::refreshInternally);

src/plugins/coreplugin/locator/spotlightlocatorfilter.cpp

@@ -205,11 +205,6 @@ static QString defaultCaseSensitiveArguments()
     return "-l 10000 -r \"%{Query:Regex}\"";
 }
 
-const char kShortcutStringDefault[] = "md";
-const bool kIncludedByDefaultDefault = false;
-
-const char kShortcutStringKey[] = "shortcut";
-const char kIncludedByDefaultKey[] = "includeByDefault";
 const char kCommandKey[] = "command";
 const char kArgumentsKey[] = "arguments";
 const char kCaseSensitiveKey[] = "caseSensitive";
@@ -244,6 +239,8 @@ static MacroExpander *createMacroExpander(const QString &query)
 SpotlightLocatorFilter::SpotlightLocatorFilter()
 {
     setId("SpotlightFileNamesLocatorFilter");
+    setDefaultShortcutString("md");
+    setDefaultIncludedByDefault(false);
     setDisplayName(tr("File Name Index"));
     setConfigurable(true);
     reset();
@@ -305,45 +302,25 @@ bool SpotlightLocatorFilter::openConfigDialog(QWidget *parent, bool &needsRefres
     return accepted;
 }
 
-QByteArray SpotlightLocatorFilter::saveState() const
+void SpotlightLocatorFilter::saveState(QJsonObject &obj) const
 {
-    QJsonObject obj;
-    if (shortcutString() != kShortcutStringDefault)
-        obj.insert(kShortcutStringKey, shortcutString());
-    if (isIncludedByDefault() != kIncludedByDefaultDefault)
-        obj.insert(kIncludedByDefaultKey, isIncludedByDefault());
     if (m_command != defaultCommand())
         obj.insert(kCommandKey, m_command);
     if (m_arguments != defaultArguments())
         obj.insert(kArgumentsKey, m_arguments);
     if (m_caseSensitiveArguments != defaultCaseSensitiveArguments())
         obj.insert(kCaseSensitiveKey, m_caseSensitiveArguments);
-    QJsonDocument doc;
-    doc.setObject(obj);
-    return doc.toJson(QJsonDocument::Compact);
 }
 
-void SpotlightLocatorFilter::restoreState(const QByteArray &state)
+void SpotlightLocatorFilter::restoreState(const QJsonObject &obj)
 {
-    QJsonDocument doc = QJsonDocument::fromJson(state);
-    if (doc.isNull() || !doc.isObject()) {
-        reset();
-        ILocatorFilter::restoreState(state); // legacy settings from Qt Creator < 4.15
-    } else {
-        const QJsonObject obj = doc.object();
-        setShortcutString(obj.value(kShortcutStringKey).toString(kShortcutStringDefault));
-        setIncludedByDefault(obj.value(kIncludedByDefaultKey).toBool(kIncludedByDefaultDefault));
-        m_command = obj.value(kCommandKey).toString(defaultCommand());
-        m_arguments = obj.value(kArgumentsKey).toString(defaultArguments());
-        m_caseSensitiveArguments = obj.value(kCaseSensitiveKey)
-                                       .toString(defaultCaseSensitiveArguments());
-    }
+    m_command = obj.value(kCommandKey).toString(defaultCommand());
+    m_arguments = obj.value(kArgumentsKey).toString(defaultArguments());
+    m_caseSensitiveArguments = obj.value(kCaseSensitiveKey).toString(defaultCaseSensitiveArguments());
 }
 
 void SpotlightLocatorFilter::reset()
 {
-    setShortcutString(kShortcutStringDefault);
-    setIncludedByDefault(kIncludedByDefaultDefault);
     m_command = defaultCommand();
     m_arguments = defaultArguments();
     m_caseSensitiveArguments = defaultCaseSensitiveArguments();

src/plugins/coreplugin/locator/spotlightlocatorfilter.h

@@ -44,8 +44,9 @@ public:
     using ILocatorFilter::openConfigDialog;
     bool openConfigDialog(QWidget *parent, bool &needsRefresh) final;
 
-    QByteArray saveState() const final;
-    void restoreState(const QByteArray &state) final;
+protected:
+    void saveState(QJsonObject &obj) const final;
+    void restoreState(const QJsonObject &obj) final;
 
 private:
     void reset();

src/plugins/coreplugin/locator/urllocatorfilter.cpp

@@ -25,9 +25,12 @@
 
 #include "urllocatorfilter.h"
 
+#include <utils/algorithm.h>
 #include <utils/stringutils.h>
 
 #include <QDesktopServices>
+#include <QJsonArray>
+#include <QJsonObject>
 #include <QMutexLocker>
 #include <QUrl>
 
@@ -136,8 +139,9 @@ UrlLocatorFilter::UrlLocatorFilter(Id id)
 UrlLocatorFilter::UrlLocatorFilter(const QString &displayName, Id id)
 {
     setId(id);
+    m_defaultDisplayName = displayName;
     setDisplayName(displayName);
-    setIncludedByDefault(false);
+    setDefaultIncludedByDefault(false);
 }
 
 UrlLocatorFilter::~UrlLocatorFilter() = default;
@@ -177,37 +181,51 @@ void UrlLocatorFilter::refresh(QFutureInterface<void> &future)
     // Nothing to refresh
 }
 
-QByteArray UrlLocatorFilter::saveState() const
+const char kDisplayNameKey[] = "displayName";
+const char kRemoteUrlsKey[] = "remoteUrls";
+
+void UrlLocatorFilter::saveState(QJsonObject &object) const
 {
-    QByteArray value;
-    QDataStream out(&value, QIODevice::WriteOnly);
-    out << m_remoteUrls.join('^');
-    out << shortcutString();
-    out << isIncludedByDefault();
-    out << displayName();
-    return value;
+    if (displayName() != m_defaultDisplayName)
+        object.insert(kDisplayNameKey, displayName());
+    if (m_remoteUrls != m_defaultUrls)
+        object.insert(kRemoteUrlsKey, QJsonArray::fromStringList(m_remoteUrls));
+}
+
+void UrlLocatorFilter::restoreState(const QJsonObject &object)
+{
+    setDisplayName(object.value(kDisplayNameKey).toString(m_defaultDisplayName));
+    m_remoteUrls = Utils::transform(object.value(kRemoteUrlsKey)
+                                        .toArray(QJsonArray::fromStringList(m_defaultUrls))
+                                        .toVariantList(),
+                                    &QVariant::toString);
 }
 
 void UrlLocatorFilter::restoreState(const QByteArray &state)
 {
-    QDataStream in(state);
+    if (isOldSetting(state)) {
+        // TODO read old settings, remove some time after Qt Creator 4.15
+        QDataStream in(state);
 
-    QString value;
-    in >> value;
-    m_remoteUrls = value.split('^', Qt::SkipEmptyParts);
+        QString value;
+        in >> value;
+        m_remoteUrls = value.split('^', Qt::SkipEmptyParts);
 
-    QString shortcut;
-    in >> shortcut;
-    setShortcutString(shortcut);
+        QString shortcut;
+        in >> shortcut;
+        setShortcutString(shortcut);
 
-    bool defaultFilter;
-    in >> defaultFilter;
-    setIncludedByDefault(defaultFilter);
+        bool defaultFilter;
+        in >> defaultFilter;
+        setIncludedByDefault(defaultFilter);
 
-    if (!in.atEnd()) {
-        QString name;
-        in >> name;
-        setDisplayName(name);
+        if (!in.atEnd()) {
+            QString name;
+            in >> name;
+            setDisplayName(name);
+        }
+    } else {
+        ILocatorFilter::restoreState(state);
     }
 }
 
@@ -232,6 +250,7 @@ bool UrlLocatorFilter::openConfigDialog(QWidget *parent, bool &needsRefresh)
 void UrlLocatorFilter::addDefaultUrl(const QString &urlTemplate)
 {
     m_remoteUrls.append(urlTemplate);
+    m_defaultUrls.append(urlTemplate);
 }
 
 QStringList UrlLocatorFilter::remoteUrls() const

src/plugins/coreplugin/locator/urllocatorfilter.h

@@ -49,7 +49,6 @@ public:
     void accept(Core::LocatorFilterEntry selection,
                 QString *newText, int *selectionStart, int *selectionLength) const override;
     void refresh(QFutureInterface<void> &future) override;
-    QByteArray saveState() const override;
     void restoreState(const QByteArray &state) override;
     bool openConfigDialog(QWidget *parent, bool &needsRefresh) override;
 
@@ -59,9 +58,13 @@ public:
     void setIsCustomFilter(bool value);
     bool isCustomFilter() const;
 
-    using ILocatorFilter::setDisplayName;
+protected:
+    void saveState(QJsonObject &object) const final;
+    void restoreState(const QJsonObject &object) final;
 
 private:
+    QString m_defaultDisplayName;
+    QStringList m_defaultUrls;
     QStringList m_remoteUrls;
     bool m_isCustomFilter = false;
     mutable QMutex m_mutex;

src/plugins/coreplugin/menubarfilter.cpp

@@ -54,7 +54,7 @@ MenuBarFilter::MenuBarFilter()
 {
     setId("Actions from the menu");
     setDisplayName(tr("Actions from the Menu"));
-    setShortcutString("t");
+    setDefaultShortcutString("t");
     connect(ICore::instance(), &ICore::contextAboutToChange, this, [this] {
         if (LocatorManager::locatorHasFocus())
             updateEnabledActionCache();

src/plugins/coreplugin/settingsdatabase.cpp

@@ -195,7 +195,21 @@ QVariant SettingsDatabase::value(const QString &key, const QVariant &defaultValu
 
 bool SettingsDatabase::contains(const QString &key) const
 {
-    return d->m_settings.contains(d->effectiveKey(key));
+    // check exact key
+    // this already caches the value
+    if (value(key).isValid())
+        return true;
+    // check for group
+    if (d->m_db.isOpen()) {
+        const QString glob = d->effectiveKey(key) + "/?*";
+        QSqlQuery query(d->m_db);
+        query.prepare(
+            QLatin1String("SELECT value FROM settings WHERE key GLOB '%1' LIMIT 1").arg(glob));
+        query.exec();
+        if (query.next())
+            return true;
+    }
+    return false;
 }
 
 void SettingsDatabase::remove(const QString &key)

src/plugins/coreplugin/settingsdatabase.h

@@ -44,6 +44,12 @@ public:
 
     void setValue(const QString &key, const QVariant &value);
     QVariant value(const QString &key, const QVariant &defaultValue = QVariant()) const;
+
+    template<typename T>
+    void setValueWithDefault(const QString &key, const T &val, const T &defaultValue);
+    template<typename T>
+    void setValueWithDefault(const QString &key, const T &val);
+
     bool contains(const QString &key) const;
     void remove(const QString &key);
 
@@ -61,4 +67,22 @@ private:
     Internal::SettingsDatabasePrivate *d;
 };
 
+template<typename T>
+void SettingsDatabase::setValueWithDefault(const QString &key, const T &val, const T &defaultValue)
+{
+    if (val == defaultValue)
+        remove(key);
+    else
+        setValue(key, QVariant::fromValue(val));
+}
+
+template<typename T>
+void SettingsDatabase::setValueWithDefault(const QString &key, const T &val)
+{
+    if (val == T())
+        remove(key);
+    else
+        setValue(key, QVariant::fromValue(val));
+}
+
 } // namespace Core

src/plugins/cpptools/cppclassesfilter.cpp

@@ -35,8 +35,8 @@ CppClassesFilter::CppClassesFilter(CppLocatorData *locatorData)
 {
     setId(Constants::CLASSES_FILTER_ID);
     setDisplayName(Constants::CLASSES_FILTER_DISPLAY_NAME);
-    setShortcutString(QLatin1String("c"));
-    setIncludedByDefault(false);
+    setDefaultShortcutString("c");
+    setDefaultIncludedByDefault(false);
 }
 
 CppClassesFilter::~CppClassesFilter() = default;

src/plugins/cpptools/cppcurrentdocumentfilter.cpp

@@ -42,9 +42,9 @@ CppCurrentDocumentFilter::CppCurrentDocumentFilter(CppTools::CppModelManager *ma
 {
     setId(Constants::CURRENT_DOCUMENT_FILTER_ID);
     setDisplayName(Constants::CURRENT_DOCUMENT_FILTER_DISPLAY_NAME);
-    setShortcutString(".");
+    setDefaultShortcutString(".");
     setPriority(High);
-    setIncludedByDefault(false);
+    setDefaultIncludedByDefault(false);
 
     search.setSymbolsToSearchFor(SymbolSearcher::Declarations |
                                  SymbolSearcher::Enums |

src/plugins/cpptools/cppfunctionsfilter.cpp

@@ -37,8 +37,8 @@ CppFunctionsFilter::CppFunctionsFilter(CppLocatorData *locatorData)
 {
     setId(Constants::FUNCTIONS_FILTER_ID);
     setDisplayName(Constants::FUNCTIONS_FILTER_DISPLAY_NAME);
-    setShortcutString("m");
-    setIncludedByDefault(false);
+    setDefaultShortcutString("m");
+    setDefaultIncludedByDefault(false);
 }
 
 CppFunctionsFilter::~CppFunctionsFilter() = default;

src/plugins/cpptools/cppincludesfilter.cpp

@@ -121,8 +121,8 @@ CppIncludesFilter::CppIncludesFilter()
 {
     setId(Constants::INCLUDES_FILTER_ID);
     setDisplayName(Constants::INCLUDES_FILTER_DISPLAY_NAME);
-    setShortcutString("ai");
-    setIncludedByDefault(true);
+    setDefaultShortcutString("ai");
+    setDefaultIncludedByDefault(true);
     setPriority(ILocatorFilter::Low);
 
     connect(ProjectExplorerPlugin::instance(), &ProjectExplorerPlugin::fileListChanged,

src/plugins/cpptools/cpplocatorfilter.cpp

@@ -43,8 +43,8 @@ CppLocatorFilter::CppLocatorFilter(CppLocatorData *locatorData)
 {
     setId(Constants::LOCATOR_FILTER_ID);
     setDisplayName(Constants::LOCATOR_FILTER_DISPLAY_NAME);
-    setShortcutString(":");
-    setIncludedByDefault(false);
+    setDefaultShortcutString(":");
+    setDefaultIncludedByDefault(false);
 }
 
 CppLocatorFilter::~CppLocatorFilter() = default;

src/plugins/help/helpindexfilter.cpp

@@ -62,8 +62,8 @@ HelpIndexFilter::HelpIndexFilter()
 {
     setId("HelpIndexFilter");
     setDisplayName(tr("Help Index"));
-    setIncludedByDefault(false);
-    setShortcutString("?");
+    setDefaultIncludedByDefault(false);
+    setDefaultShortcutString("?");
 
     m_icon = Utils::Icons::BOOKMARK.icon();
     connect(Core::HelpManager::Signals::instance(), &Core::HelpManager::Signals::setupFinished,

src/plugins/languageclient/locatorfilter.cpp

@@ -47,8 +47,8 @@ DocumentLocatorFilter::DocumentLocatorFilter()
 {
     setId(Constants::LANGUAGECLIENT_DOCUMENT_FILTER_ID);
     setDisplayName(Constants::LANGUAGECLIENT_DOCUMENT_FILTER_DISPLAY_NAME);
-    setShortcutString(".");
-    setIncludedByDefault(false);
+    setDefaultShortcutString(".");
+    setDefaultIncludedByDefault(false);
     setPriority(ILocatorFilter::Low);
     connect(Core::EditorManager::instance(), &Core::EditorManager::currentEditorChanged,
             this, &DocumentLocatorFilter::updateCurrentClient);
@@ -208,8 +208,8 @@ WorkspaceLocatorFilter::WorkspaceLocatorFilter(const QVector<SymbolKind> &filter
 {
     setId(Constants::LANGUAGECLIENT_WORKSPACE_FILTER_ID);
     setDisplayName(Constants::LANGUAGECLIENT_WORKSPACE_FILTER_DISPLAY_NAME);
-    setShortcutString(":");
-    setIncludedByDefault(false);
+    setDefaultShortcutString(":");
+    setDefaultIncludedByDefault(false);
     setPriority(ILocatorFilter::Low);
 }
 
@@ -298,7 +298,7 @@ WorkspaceClassLocatorFilter::WorkspaceClassLocatorFilter()
 {
     setId(Constants::LANGUAGECLIENT_WORKSPACE_CLASS_FILTER_ID);
     setDisplayName(Constants::LANGUAGECLIENT_WORKSPACE_CLASS_FILTER_DISPLAY_NAME);
-    setShortcutString("c");
+    setDefaultShortcutString("c");
 }
 
 WorkspaceMethodLocatorFilter::WorkspaceMethodLocatorFilter()
@@ -306,7 +306,7 @@ WorkspaceMethodLocatorFilter::WorkspaceMethodLocatorFilter()
 {
     setId(Constants::LANGUAGECLIENT_WORKSPACE_METHOD_FILTER_ID);
     setDisplayName(Constants::LANGUAGECLIENT_WORKSPACE_METHOD_FILTER_DISPLAY_NAME);
-    setShortcutString("m");
+    setDefaultShortcutString("m");
 }
 
 } // namespace LanguageClient

src/plugins/macros/macrolocatorfilter.cpp

@@ -42,7 +42,7 @@ MacroLocatorFilter::MacroLocatorFilter()
 {
     setId("Macros");
     setDisplayName(tr("Text Editing Macros"));
-    setShortcutString("rm");
+    setDefaultShortcutString("rm");
 }
 
 MacroLocatorFilter::~MacroLocatorFilter() = default;

src/plugins/projectexplorer/allprojectsfilter.cpp

@@ -40,8 +40,8 @@ AllProjectsFilter::AllProjectsFilter()
 {
     setId("Files in any project");
     setDisplayName(tr("Files in Any Project"));
-    setShortcutString(QString(QLatin1Char('a')));
-    setIncludedByDefault(true);
+    setDefaultShortcutString("a");
+    setDefaultIncludedByDefault(true);
 
     connect(ProjectExplorerPlugin::instance(), &ProjectExplorerPlugin::fileListChanged,
             this, &AllProjectsFilter::markFilesAsOutOfDate);

src/plugins/projectexplorer/currentprojectfilter.cpp

@@ -35,12 +35,13 @@ using namespace Core;
 using namespace ProjectExplorer;
 using namespace ProjectExplorer::Internal;
 
-CurrentProjectFilter::CurrentProjectFilter() : BaseFileFilter()
+CurrentProjectFilter::CurrentProjectFilter()
+    : BaseFileFilter()
 {
     setId("Files in current project");
     setDisplayName(tr("Files in Current Project"));
-    setShortcutString(QString(QLatin1Char('p')));
-    setIncludedByDefault(false);
+    setDefaultShortcutString("p");
+    setDefaultIncludedByDefault(false);
 
     connect(ProjectTree::instance(), &ProjectTree::currentProjectChanged,
             this, &CurrentProjectFilter::currentProjectChanged);

src/plugins/projectexplorer/projectexplorer.cpp

@@ -2798,8 +2798,9 @@ ProjectExplorerPluginPrivate::ProjectExplorerPluginPrivate()
     : m_allProjectDirectoriesFilter("Files in All Project Directories")
 {
     m_allProjectDirectoriesFilter.setDisplayName(m_allProjectDirectoriesFilter.id().toString());
-    m_allProjectDirectoriesFilter.setShortcutString("a");      // shared with "Files in Any Project"
-    m_allProjectDirectoriesFilter.setIncludedByDefault(false); // but not included in default
+    // shared with "Files in Any Project":
+    m_allProjectDirectoriesFilter.setDefaultShortcutString("a");
+    m_allProjectDirectoriesFilter.setDefaultIncludedByDefault(false); // but not included in default
     m_allProjectDirectoriesFilter.setFilters({});
     m_allProjectDirectoriesFilter.setIsCustomFilter(false);
 }

src/plugins/qmljstools/qmljsfunctionfilter.cpp

@@ -44,8 +44,8 @@ FunctionFilter::FunctionFilter(LocatorData *data, QObject *parent)
 {
     setId("Functions");
     setDisplayName(tr("QML Functions"));
-    setShortcutString("m");
-    setIncludedByDefault(false);
+    setDefaultShortcutString("m");
+    setDefaultIncludedByDefault(false);
 }
 
 FunctionFilter::~FunctionFilter() = default;

src/plugins/texteditor/linenumberfilter.cpp

@@ -49,8 +49,8 @@ LineNumberFilter::LineNumberFilter(QObject *parent)
     setId("Line in current document");
     setDisplayName(tr("Line in Current Document"));
     setPriority(High);
-    setShortcutString("l");
-    setIncludedByDefault(true);
+    setDefaultShortcutString("l");
+    setDefaultIncludedByDefault(true);
 }
 
 void LineNumberFilter::prepareSearch(const QString &entry)