sanya-dbms/db_manager/dlg_sql_window.py

"""
/***************************************************************************
Name                 : DB Manager
Description          : Database manager plugin for QGIS
Date                 : May 23, 2011
copyright            : (C) 2011 by Giuseppe Sucameli
email                : brush.tyler@gmail.com

The content of this file is based on
- PG_Manager by Martin Dobias (GPLv2 license)
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
"""
from hashlib import md5

import os

from qgis.PyQt.QtCore import Qt, pyqtSignal, QDir, QCoreApplication
from qgis.PyQt.QtWidgets import (QDialog,
                                 QWidget,
                                 QAction,
                                 QApplication,
                                 QInputDialog,
                                 QStyledItemDelegate,
                                 QTableWidgetItem,
                                 QFileDialog,
                                 QMessageBox
                                 )
from qgis.PyQt.QtGui import (QKeySequence,
                             QCursor,
                             QClipboard,
                             QIcon,
                             QStandardItemModel,
                             QStandardItem
                             )
from qgis.PyQt.Qsci import QsciAPIs, QsciScintilla

from qgis.core import (
    QgsProject,
    QgsApplication,
    QgsTask,
    QgsSettings,
    QgsMapLayerType
)
from qgis.utils import OverrideCursor

from .db_plugins.plugin import BaseError
from .db_plugins.postgis.plugin import PGDatabase
from .dlg_db_error import DlgDbError
from .dlg_query_builder import QueryBuilderDlg

try:
    from qgis.gui import QgsCodeEditorSQL  # NOQA
except:
    from .sqledit import SqlEdit
    from qgis import gui

    gui.QgsCodeEditorSQL = SqlEdit

from .ui.ui_DlgSqlWindow import Ui_DbManagerDlgSqlWindow as Ui_Dialog

import re


def check_comments_in_sql(raw_sql_input):
    lines = []
    for line in raw_sql_input.splitlines():
        if not line.strip().startswith('--'):
            if '--' in line:
                comments = re.finditer(r'--', line)
                comment_positions = [
                    match.start()
                    for match in comments
                ]
                identifiers = re.finditer(r'"(?:[^"]|"")*"', line)
                quotes = re.finditer(r"'(?:[^']|'')*'", line)
                quote_positions = []
                for match in identifiers:
                    quote_positions.append((match.start(), match.end()))
                for match in quotes:
                    quote_positions.append((match.start(), match.end()))
                unquoted_comments = comment_positions.copy()
                for comment in comment_positions:
                    for quote_position in quote_positions:
                        if comment >= quote_position[0] and comment < quote_position[1]:
                            unquoted_comments.remove(comment)
                if len(unquoted_comments) > 0:
                    lines.append(line[:unquoted_comments[0]])
                else:
                    lines.append(line)
            else:
                lines.append(line)
    sql = ' '.join(lines)
    return sql.strip()


class DlgSqlWindow(QWidget, Ui_Dialog):
    nameChanged = pyqtSignal(str)
    QUERY_HISTORY_LIMIT = 20
    hasChanged = False

    def __init__(self, iface, db, parent=None):
        QWidget.__init__(self, parent)
        self.mainWindow = parent
        self.iface = iface
        self.db = db
        self.dbType = db.connection().typeNameString()
        self.connectionName = db.connection().connectionName()
        self.filter = ""
        self.modelAsync = None
        self.allowMultiColumnPk = isinstance(db,
                                             PGDatabase)  # at the moment only PostgreSQL allows a primary key to span multiple columns, SpatiaLite doesn't
        self.aliasSubQuery = isinstance(db, PGDatabase)  # only PostgreSQL requires subqueries to be aliases
        self.setupUi(self)
        self.setWindowTitle(
            self.tr("{0} - {1} [{2}]").format(self.windowTitle(), self.connectionName, self.dbType))

        self.defaultLayerName = self.tr('QueryLayer')

        if self.allowMultiColumnPk:
            self.uniqueColumnCheck.setText(self.tr("Column(s) with unique values"))
        else:
            self.uniqueColumnCheck.setText(self.tr("Column with unique values"))

        self.editSql.setFocus()
        self.editSql.setVerticalScrollBarPolicy(Qt.ScrollBarAsNeeded)
        self.editSql.setLineNumbersVisible(True)
        self.initCompleter()
        self.editSql.textChanged.connect(lambda: self.setHasChanged(True))

        settings = QgsSettings()
        self.history = settings.value('DB_Manager/queryHistory/' + self.dbType, {self.connectionName: []})
        if self.connectionName not in self.history:
            self.history[self.connectionName] = []

        self.queryHistoryWidget.setVisible(False)
        self.queryHistoryTableWidget.verticalHeader().hide()
        self.queryHistoryTableWidget.doubleClicked.connect(self.insertQueryInEditor)
        self.populateQueryHistory()
        self.btnQueryHistory.toggled.connect(self.showHideQueryHistory)

        self.btnCancel.setEnabled(False)
        self.btnCancel.clicked.connect(self.executeSqlCanceled)
        self.btnCancel.setShortcut(QKeySequence.Cancel)
        self.progressBar.setEnabled(False)
        self.progressBar.setRange(0, 100)
        self.progressBar.setValue(0)
        self.progressBar.setFormat("")
        self.progressBar.setAlignment(Qt.AlignCenter)

        # allow copying results
        copyAction = QAction("copy", self)
        self.viewResult.addAction(copyAction)
        copyAction.setShortcuts(QKeySequence.Copy)

        copyAction.triggered.connect(self.copySelectedResults)

        self.btnExecute.clicked.connect(self.executeSql)
        self.btnSetFilter.clicked.connect(self.setFilter)
        self.btnClear.clicked.connect(self.clearSql)

        self.presetStore.clicked.connect(self.storePreset)
        self.presetSaveAsFile.clicked.connect(self.saveAsFilePreset)
        self.presetLoadFile.clicked.connect(self.loadFilePreset)
        self.presetDelete.clicked.connect(self.deletePreset)
        self.presetCombo.activated[str].connect(self.loadPreset)
        self.presetCombo.activated[str].connect(self.presetName.setText)

        self.updatePresetsCombobox()

        self.geomCombo.setEditable(True)
        self.geomCombo.lineEdit().setReadOnly(True)

        self.uniqueCombo.setEditable(True)
        self.uniqueCombo.lineEdit().setReadOnly(True)
        self.uniqueModel = QStandardItemModel(self.uniqueCombo)
        self.uniqueCombo.setModel(self.uniqueModel)
        if self.allowMultiColumnPk:
            self.uniqueCombo.setItemDelegate(QStyledItemDelegate())
            self.uniqueModel.itemChanged.connect(self.uniqueChanged)  # react to the (un)checking of an item
            self.uniqueCombo.lineEdit().textChanged.connect(
                self.uniqueTextChanged)  # there are other events that change the displayed text and some of them can not be caught directly

        # hide the load query as layer if feature is not supported
        self._loadAsLayerAvailable = self.db.connector.hasCustomQuerySupport()
        self.loadAsLayerGroup.setVisible(self._loadAsLayerAvailable)
        if self._loadAsLayerAvailable:
            self.layerTypeWidget.hide()  # show if load as raster is supported
            self.loadLayerBtn.clicked.connect(self.loadSqlLayer)
            self.getColumnsBtn.clicked.connect(self.fillColumnCombos)
            self.loadAsLayerGroup.toggled.connect(self.loadAsLayerToggled)
            self.loadAsLayerToggled(False)

        self._createViewAvailable = self.db.connector.hasCreateSpatialViewSupport()
        self.btnCreateView.setVisible(self._createViewAvailable)
        if self._createViewAvailable:
            self.btnCreateView.clicked.connect(self.createView)

        self.queryBuilderFirst = True
        self.queryBuilderBtn.setIcon(QIcon(":/db_manager/icons/sql.gif"))
        self.queryBuilderBtn.clicked.connect(self.displayQueryBuilder)

        self.presetName.textChanged.connect(self.nameChanged)

    def insertQueryInEditor(self, item):
        sql = item.data(Qt.DisplayRole)
        self.editSql.insertText(sql)

    def showHideQueryHistory(self, visible):
        self.queryHistoryWidget.setVisible(visible)

    def populateQueryHistory(self):
        self.queryHistoryTableWidget.clearContents()
        self.queryHistoryTableWidget.setRowCount(0)
        dictlist = self.history[self.connectionName]

        if not dictlist:
            return

        for i in range(len(dictlist)):
            self.queryHistoryTableWidget.insertRow(0)
            queryItem = QTableWidgetItem(dictlist[i]['query'])
            rowsItem = QTableWidgetItem(str(dictlist[i]['rows']))
            durationItem = QTableWidgetItem(str(dictlist[i]['secs']))
            self.queryHistoryTableWidget.setItem(0, 0, queryItem)
            self.queryHistoryTableWidget.setItem(0, 1, rowsItem)
            self.queryHistoryTableWidget.setItem(0, 2, durationItem)

        self.queryHistoryTableWidget.resizeColumnsToContents()
        self.queryHistoryTableWidget.resizeRowsToContents()

    def writeQueryHistory(self, sql, affectedRows, secs):
        if len(self.history[self.connectionName]) >= self.QUERY_HISTORY_LIMIT:
            self.history[self.connectionName].pop(0)

        settings = QgsSettings()
        self.history[self.connectionName].append({'query': sql,
                                                  'rows': affectedRows,
                                                  'secs': secs})
        settings.setValue('DB_Manager/queryHistory/' + self.dbType, self.history)

        self.populateQueryHistory()

    def getQueryHash(self, name):
        return 'q%s' % md5(name.encode('utf8')).hexdigest()

    def updatePresetsCombobox(self):
        self.presetCombo.clear()

        names = []
        entries = QgsProject.instance().subkeyList('DBManager', 'savedQueries')
        for entry in entries:
            name = QgsProject.instance().readEntry('DBManager', 'savedQueries/' + entry + '/name')[0]
            names.append(name)

        for name in sorted(names):
            self.presetCombo.addItem(name)
        self.presetCombo.setCurrentIndex(-1)

    def storePreset(self):
        query = self._getSqlQuery()
        if query == "":
            return
        name = str(self.presetName.text())
        QgsProject.instance().writeEntry('DBManager', 'savedQueries/' + self.getQueryHash(name) + '/name', name)
        QgsProject.instance().writeEntry('DBManager', 'savedQueries/' + self.getQueryHash(name) + '/query', query)
        index = self.presetCombo.findText(name)
        if index == -1:
            self.presetCombo.addItem(name)
            self.presetCombo.setCurrentIndex(self.presetCombo.count() - 1)
        else:
            self.presetCombo.setCurrentIndex(index)

    def saveAsFilePreset(self):
        settings = QgsSettings()
        lastDir = settings.value('DB_Manager/lastDirSQLFIle', "")

        query = self.editSql.text()
        if query == "":
            return

        filename, _ = QFileDialog.getSaveFileName(
            self,
            self.tr('Save SQL Query'),
            lastDir,
            self.tr("SQL File (*.sql *.SQL)"))

        if filename:
            if not filename.lower().endswith('.sql'):
                filename += ".sql"

            with open(filename, 'w') as f:
                f.write(query)
                lastDir = os.path.dirname(filename)
                settings.setValue('DB_Manager/lastDirSQLFile', lastDir)

    def loadFilePreset(self):
        settings = QgsSettings()
        lastDir = settings.value('DB_Manager/lastDirSQLFIle', "")

        filename, _ = QFileDialog.getOpenFileName(
            self,
            self.tr("Load SQL Query"),
            lastDir,
            self.tr("SQL File (*.sql *.SQL);;All Files (*)"))

        if filename:
            with open(filename) as f:
                self.editSql.clear()
                for line in f:
                    self.editSql.insertText(line)
                lastDir = os.path.dirname(filename)
                settings.setValue('DB_Manager/lastDirSQLFile', lastDir)

    def deletePreset(self):
        name = self.presetCombo.currentText()
        QgsProject.instance().removeEntry('DBManager', 'savedQueries/' + self.getQueryHash(name))
        self.presetCombo.removeItem(self.presetCombo.findText(name))
        self.presetCombo.setCurrentIndex(-1)

    def loadPreset(self, name):
        query = QgsProject.instance().readEntry('DBManager', 'savedQueries/' + self.getQueryHash(name) + '/query')[0]
        self.editSql.setText(query)

    def loadAsLayerToggled(self, checked):
        self.loadAsLayerGroup.setChecked(checked)
        self.loadAsLayerWidget.setVisible(checked)
        if checked:
            self.fillColumnCombos()

    def clearSql(self):
        self.editSql.clear()
        self.editSql.setFocus()
        self.filter = ""
        self.setHasChanged(True)

    def updateUiWhileSqlExecution(self, status):
        if status:
            for i in range(0, self.mainWindow.tabs.count()):
                if i != self.mainWindow.tabs.currentIndex():
                    self.mainWindow.tabs.setTabEnabled(i, False)

            self.mainWindow.menuBar.setEnabled(False)
            self.mainWindow.toolBar.setEnabled(False)
            self.mainWindow.tree.setEnabled(False)

            for w in self.findChildren(QWidget):
                w.setEnabled(False)

            self.btnCancel.setEnabled(True)
            self.progressBar.setEnabled(True)
            self.progressBar.setRange(0, 0)
        else:
            for i in range(0, self.mainWindow.tabs.count()):
                if i != self.mainWindow.tabs.currentIndex():
                    self.mainWindow.tabs.setTabEnabled(i, True)

            self.mainWindow.refreshTabs()
            self.mainWindow.menuBar.setEnabled(True)
            self.mainWindow.toolBar.setEnabled(True)
            self.mainWindow.tree.setEnabled(True)

            for w in self.findChildren(QWidget):
                w.setEnabled(True)

            self.btnCancel.setEnabled(False)
            self.progressBar.setRange(0, 100)
            self.progressBar.setEnabled(False)

    def executeSqlCanceled(self):
        self.btnCancel.setEnabled(False)
        self.btnCancel.setText(QCoreApplication.translate("DlgSqlWindow", "Canceling…"))
        self.modelAsync.cancel()

    def executeSqlCompleted(self):
        self.updateUiWhileSqlExecution(False)

        with OverrideCursor(Qt.WaitCursor):
            if self.modelAsync.task.status() == QgsTask.Complete:
                model = self.modelAsync.model
                self.showError(None)
                self.viewResult.setModel(model)
                self.lblResult.setText(self.tr("{0} rows, {1:.3f} seconds").format(model.affectedRows(), model.secs()))
                cols = self.viewResult.model().columnNames()
                quotedCols = [
                    self.db.connector.quoteId(col)
                    for col in cols
                ]

                self.setColumnCombos(cols, quotedCols)

                self.writeQueryHistory(self.modelAsync.task.sql, model.affectedRows(), model.secs())
                self.update()
            elif not self.modelAsync.canceled:
                self.showError(self.modelAsync.error)

                self.uniqueModel.clear()
                self.geomCombo.clear()

            self.btnCancel.setText(self.tr("Cancel"))

    def executeSql(self):
        sql = self._getExecutableSqlQuery()
        if sql == "":
            return

        # delete the old model
        old_model = self.viewResult.model()
        self.viewResult.setModel(None)
        if old_model:
            old_model.deleteLater()

        try:
            self.modelAsync = self.db.sqlResultModelAsync(sql, self)
            self.modelAsync.done.connect(self.executeSqlCompleted)
            self.updateUiWhileSqlExecution(True)
            QgsApplication.taskManager().addTask(self.modelAsync.task)
        except Exception as e:
            self.showError(e)
            self.uniqueModel.clear()
            self.geomCombo.clear()
            return

    def showError(self, error):
        '''Shows the error or hides it if error is None'''
        if error:
            self.viewResult.setVisible(False)
            self.errorText.setVisible(True)
            self.errorText.setText(error.msg)
            self.errorText.setWrapMode(QsciScintilla.WrapWord)
        else:
            self.viewResult.setVisible(True)
            self.errorText.setVisible(False)

    def _getSqlLayer(self, _filter):
        hasUniqueField = self.uniqueColumnCheck.checkState() == Qt.Checked
        if hasUniqueField and self.allowMultiColumnPk:
            uniqueFieldName = ",".join(
                item.data()
                for item in self.uniqueModel.findItems("*", Qt.MatchWildcard)
                if item.checkState() == Qt.Checked
            )
        elif (
            hasUniqueField
            and not self.allowMultiColumnPk
            and self.uniqueCombo.currentIndex() >= 0
        ):
            uniqueFieldName = self.uniqueModel.item(self.uniqueCombo.currentIndex()).data()
        else:
            uniqueFieldName = None
        hasGeomCol = self.hasGeometryCol.checkState() == Qt.Checked
        if hasGeomCol:
            geomFieldName = self.geomCombo.currentText()
        else:
            geomFieldName = None

        query = self._getExecutableSqlQuery()
        if query == "":
            return None

        # remove a trailing ';' from query if present
        if query.strip().endswith(';'):
            query = query.strip()[:-1]

        layerType = QgsMapLayerType.VectorLayer if self.vectorRadio.isChecked() else QgsMapLayerType.RasterLayer

        # get a new layer name
        names = []
        for layer in list(QgsProject.instance().mapLayers().values()):
            names.append(layer.name())

        layerName = self.layerNameEdit.text()
        if layerName == "":
            layerName = self.defaultLayerName
        newLayerName = layerName
        index = 1
        while newLayerName in names:
            index += 1
            newLayerName = "%s_%d" % (layerName, index)

        # create the layer
        layer = self.db.toSqlLayer(query, geomFieldName, uniqueFieldName, newLayerName, layerType,
                                   self.avoidSelectById.isChecked(), _filter)
        if layer.isValid():
            return layer
        else:
            e = BaseError(self.tr("There was an error creating the SQL layer, please check the logs for further information."))
            DlgDbError.showError(e, self)
            return None

    def loadSqlLayer(self):
        with OverrideCursor(Qt.WaitCursor):
            layer = self._getSqlLayer(self.filter)
            if layer is None:
                return

            QgsProject.instance().addMapLayers([layer], True)

    def fillColumnCombos(self):
        query = self._getExecutableSqlQuery()
        if query == "":
            return

        with OverrideCursor(Qt.WaitCursor):
            # remove a trailing ';' from query if present
            if query.strip().endswith(';'):
                query = query.strip()[:-1]

            # get all the columns
            quotedCols = []
            connector = self.db.connector
            if self.aliasSubQuery:
                # get a new alias
                aliasIndex = 0
                while True:
                    alias = "_subQuery__%d" % aliasIndex
                    escaped = re.compile('\\b("?)' + re.escape(alias) + '\\1\\b')
                    if not escaped.search(query):
                        break
                    aliasIndex += 1

                sql = "SELECT * FROM (%s\n) AS %s LIMIT 0" % (str(query), connector.quoteId(alias))
            else:
                sql = "SELECT * FROM (%s\n) WHERE 1=0" % str(query)

            c = None
            try:
                c = connector._execute(None, sql)
                cols = connector._get_cursor_columns(c)
                for col in cols:
                    quotedCols.append(connector.quoteId(col))

            except BaseError as e:
                DlgDbError.showError(e, self)
                self.uniqueModel.clear()
                self.geomCombo.clear()
                return

            finally:
                if c:
                    c.close()
                    del c

            self.setColumnCombos(cols, quotedCols)

    def setColumnCombos(self, cols, quotedCols):
        # get sensible default columns. do this before sorting in case there's hints in the column order (e.g., id is more likely to be first)
        try:
            defaultGeomCol = next(col for col in cols if col in ['geom', 'geometry', 'the_geom', 'way'])
        except:
            defaultGeomCol = None
        try:
            defaultUniqueCol = [col for col in cols if 'id' in col][0]
        except:
            defaultUniqueCol = None

        colNames = sorted(zip(cols, quotedCols))
        newItems = []
        uniqueIsFilled = False
        for (col, quotedCol) in colNames:
            item = QStandardItem(col)
            item.setData(quotedCol)
            item.setEnabled(True)
            item.setCheckable(self.allowMultiColumnPk)
            item.setSelectable(not self.allowMultiColumnPk)
            if self.allowMultiColumnPk:
                matchingItems = self.uniqueModel.findItems(col)
                if matchingItems:
                    item.setCheckState(matchingItems[0].checkState())
                    uniqueIsFilled = uniqueIsFilled or matchingItems[0].checkState() == Qt.Checked
                else:
                    item.setCheckState(Qt.Unchecked)
            newItems.append(item)
        if self.allowMultiColumnPk:
            self.uniqueModel.clear()
            self.uniqueModel.appendColumn(newItems)
            self.uniqueChanged()
        else:
            previousUniqueColumn = self.uniqueCombo.currentText()
            self.uniqueModel.clear()
            self.uniqueModel.appendColumn(newItems)
            if self.uniqueModel.findItems(previousUniqueColumn):
                self.uniqueCombo.setEditText(previousUniqueColumn)
                uniqueIsFilled = True

        oldGeometryColumn = self.geomCombo.currentText()
        self.geomCombo.clear()
        self.geomCombo.addItems(cols)
        self.geomCombo.setCurrentIndex(self.geomCombo.findText(oldGeometryColumn, Qt.MatchExactly))

        # set sensible default columns if the columns are not already set
        try:
            if self.geomCombo.currentIndex() == -1:
                self.geomCombo.setCurrentIndex(cols.index(defaultGeomCol))
        except:
            pass
        items = self.uniqueModel.findItems(defaultUniqueCol)
        if items and not uniqueIsFilled:
            if self.allowMultiColumnPk:
                items[0].setCheckState(Qt.Checked)
            else:
                self.uniqueCombo.setEditText(defaultUniqueCol)

    def copySelectedResults(self):
        if len(self.viewResult.selectedIndexes()) <= 0:
            return
        model = self.viewResult.model()

        # convert to string using tab as separator
        text = model.headerToString("\t")
        for idx in self.viewResult.selectionModel().selectedRows():
            text += "\n" + model.rowToString(idx.row(), "\t")

        QApplication.clipboard().setText(text, QClipboard.Selection)
        QApplication.clipboard().setText(text, QClipboard.Clipboard)

    def initCompleter(self):
        dictionary = None
        if self.db:
            dictionary = self.db.connector.getSqlDictionary()
        if not dictionary:
            # use the generic sql dictionary
            from .sql_dictionary import getSqlDictionary

            dictionary = getSqlDictionary()

        wordlist = []
        for value in dictionary.values():
            wordlist += value  # concat lists
        wordlist = list(set(wordlist))  # remove duplicates

        api = QsciAPIs(self.editSql.lexer())
        for word in wordlist:
            api.add(word)

        api.prepare()
        self.editSql.lexer().setAPIs(api)

    def displayQueryBuilder(self):
        dlg = QueryBuilderDlg(self.iface, self.db, self, reset=self.queryBuilderFirst)
        self.queryBuilderFirst = False
        r = dlg.exec_()
        if r == QDialog.Accepted:
            self.editSql.setText(dlg.query)

    def createView(self):
        name, ok = QInputDialog.getText(None, self.tr("View Name"), self.tr("View name"))
        if ok:
            try:
                self.db.connector.createSpatialView(name, self._getExecutableSqlQuery())
            except BaseError as e:
                DlgDbError.showError(e, self)

    def _getSqlQuery(self):
        sql = self.editSql.selectedText()
        if len(sql) == 0:
            sql = self.editSql.text()
        return sql

    def _getExecutableSqlQuery(self):
        sql = self._getSqlQuery().strip()

        uncommented_sql = check_comments_in_sql(sql)
        uncommented_sql = uncommented_sql.rstrip(';')
        return uncommented_sql

    def uniqueChanged(self):
        # when an item is (un)checked, simply trigger an update of the combobox text
        self.uniqueTextChanged(None)

    def uniqueTextChanged(self, text):
        # Whenever there is new text displayed in the combobox, check if it is the correct one and if not, display the correct one.
        label = ", ".join(
            item.text()
            for item in self.uniqueModel.findItems("*", Qt.MatchWildcard)
            if item.checkState() == Qt.Checked
        )
        if text != label:
            self.uniqueCombo.setEditText(label)

    def setFilter(self):
        from qgis.gui import QgsQueryBuilder
        layer = self._getSqlLayer("")
        if not layer:
            return

        dlg = QgsQueryBuilder(layer)
        dlg.setSql(self.filter)
        if dlg.exec_():
            self.filter = dlg.sql()
        layer.deleteLater()

    def setHasChanged(self, hasChanged):
        self.hasChanged = hasChanged

    def close(self):
        if self.hasChanged:
            ret = QMessageBox.question(
                self, self.tr('Unsaved Changes?'),
                self.tr('There are unsaved changes. Do you want to keep them?'),
                QMessageBox.Save | QMessageBox.Cancel | QMessageBox.Discard, QMessageBox.Cancel)

            if ret == QMessageBox.Save:
                self.saveAsFilePreset()
                return True
            elif ret == QMessageBox.Discard:
                return True
            else:
                return False
        else:
            return True