New Shapefile Layer dialog: avoid warning message on user cancel

Also add better error message reporting, and deprecate horrible API.

(cherry picked from commit 9a723d9)

python/gui/auto_generated/qgsnewvectorlayerdialog.sip.in

@@ -17,14 +17,46 @@ class QgsNewVectorLayerDialog: QDialog
 %End
   public:
 
-    static QString runAndCreateLayer( QWidget *parent = 0, QString *enc = 0, const QgsCoordinateReferenceSystem &crs = QgsCoordinateReferenceSystem() );
+ static QString runAndCreateLayer( QWidget *parent = 0, QString *enc = 0, const QgsCoordinateReferenceSystem &crs = QgsCoordinateReferenceSystem(),
+        const QString &initialPath = QString() ) /Deprecated/;
 %Docstring
 Runs the dialog and creates a layer matching the dialog parameters.
 
+If the ``initialPath`` argument is specified, then the dialog will default to the specified filename.
+
 :return: fileName on success, empty string use aborted, QString() if creation failed
+
+.. deprecated:: in QGIS 3.4.5 - use execAndCreateLayer() instead.
+%End
+
+    static QString execAndCreateLayer( QString &errorMessage /Out/, QWidget *parent = 0, const QString &initialPath = QString(), QString *encoding /Out/ = 0, const QgsCoordinateReferenceSystem &crs = QgsCoordinateReferenceSystem() );
+%Docstring
+Runs the dialog and creates a layer matching the dialog parameters.
+
+If the ``initialPath`` argument is specified, then the dialog will default to the specified filename.
+
+Returns a filename if the dialog was accepted, or an empty string if the dialog was canceled.
+If the dialog was accepted but an error occurred while creating the file, then the function will
+return an empty string and ``errorMessage`` will contain the error message.
+
+If ``encoding`` is specified, it will be set to the encoding of the created file.
+
+:param errorMessage: will be set to any error message encountered during layer creation
+:param parent: parent widget for dialog
+:param initialPath: initial file path to show in dialog
+:param encoding: if specified, will be set to file encoding of created layer
+:param crs: default layer CRS to show in dialog
+
+:return: Newly created file name, or an empty string if user canceled or an error occurred.
+
+
+.. versionadded:: 3.4.5
 %End
 
     QgsNewVectorLayerDialog( QWidget *parent /TransferThis/ = 0, Qt::WindowFlags fl = QgsGuiUtils::ModalDialogFlags );
+%Docstring
+New dialog constructor.
+%End
     ~QgsNewVectorLayerDialog();
     QgsWkbTypes::Type selectedType() const;
 %Docstring
@@ -42,9 +74,21 @@ Returns the file format for storage
 %Docstring
 Returns the file format for storage
 %End
+
     QString filename() const;
 %Docstring
 Returns the name for the new layer
+
+.. seealso:: :py:func:`setFilename`
+%End
+
+    void setFilename( const QString &filename );
+%Docstring
+Sets the initial file name to show in the dialog.
+
+.. seealso:: :py:func:`filename`
+
+.. versionadded:: 3.4.5
 %End
 
     QgsCoordinateReferenceSystem crs() const;

src/app/qgisapp.cpp

@@ -5602,7 +5602,8 @@ void QgisApp::fileNewFromTemplateAction( QAction *qAction )
 void QgisApp::newVectorLayer()
 {
   QString enc;
-  QString fileName = QgsNewVectorLayerDialog::runAndCreateLayer( this, &enc, QgsProject::instance()->defaultCrsForNewLayers() );
+  QString error;
+  QString fileName = QgsNewVectorLayerDialog::execAndCreateLayer( error, this, QString(), &enc, QgsProject::instance()->defaultCrsForNewLayers() );
 
   if ( !fileName.isEmpty() )
   {
@@ -5612,12 +5613,12 @@ void QgisApp::newVectorLayer()
     //todo: the last parameter will change accordingly to layer type
     addVectorLayers( fileNames, enc, QStringLiteral( "file" ) );
   }
-  else if ( fileName.isNull() )
+  else if ( !error.isEmpty() )
   {
-    QLabel *msgLabel = new QLabel( tr( "Layer creation failed. Please check the <a href=\"#messageLog\">message log</a> for further information." ), messageBar() );
+    QLabel *msgLabel = new QLabel( tr( "Layer creation failed: %1" ).arg( error ), messageBar() );
     msgLabel->setWordWrap( true );
     connect( msgLabel, &QLabel::linkActivated, mLogDock, &QWidget::show );
-    QgsMessageBarItem *item = new QgsMessageBarItem( msgLabel, Qgis::Warning );
+    QgsMessageBarItem *item = new QgsMessageBarItem( msgLabel, Qgis::Critical );
     messageBar()->pushItem( item );
   }
 }

src/gui/qgsnewvectorlayerdialog.cpp

@@ -30,7 +30,7 @@
 #include <QComboBox>
 #include <QLibrary>
 #include <QFileDialog>
-
+#include <QMessageBox>
 
 QgsNewVectorLayerDialog::QgsNewVectorLayerDialog( QWidget *parent, Qt::WindowFlags fl )
   : QDialog( parent, fl )
@@ -105,6 +105,7 @@ QgsNewVectorLayerDialog::QgsNewVectorLayerDialog( QWidget *parent, Qt::WindowFla
 
   mFileName->setStorageMode( QgsFileWidget::SaveFile );
   mFileName->setFilter( QgsVectorFileWriter::filterForDriver( mFileFormatComboBox->currentData( Qt::UserRole ).toString() ) );
+  mFileName->setConfirmOverwrite( false );
   mFileName->setDialogTitle( tr( "Save Layer As" ) );
   mFileName->setDefaultRoot( settings.value( QStringLiteral( "UI/lastVectorFileFilterDir" ), QDir::homePath() ).toString() );
   connect( mFileName, &QgsFileWidget::fileChanged, this, [ = ]
@@ -246,22 +247,43 @@ QString QgsNewVectorLayerDialog::filename() const
   return mFileName->filePath();
 }
 
+void QgsNewVectorLayerDialog::setFilename( const QString &filename )
+{
+  mFileName->setFilePath( filename );
+}
+
 void QgsNewVectorLayerDialog::checkOk()
 {
   bool ok = ( !mFileName->filePath().isEmpty() && mAttributeView->topLevelItemCount() > 0 );
   mOkButton->setEnabled( ok );
 }
 
 // this is static
-QString QgsNewVectorLayerDialog::runAndCreateLayer( QWidget *parent, QString *pEnc, const QgsCoordinateReferenceSystem &crs )
+QString QgsNewVectorLayerDialog::runAndCreateLayer( QWidget *parent, QString *pEnc, const QgsCoordinateReferenceSystem &crs, const QString &initialPath )
+{
+  QString error;
+  QString res = execAndCreateLayer( error, parent, initialPath, pEnc, crs );
+  if ( res.isEmpty() && error.isEmpty() )
+    res = QString( "" ); // maintain gross earlier API compatibility
+  return res;
+}
+
+QString QgsNewVectorLayerDialog::execAndCreateLayer( QString &errorMessage, QWidget *parent, const QString &initialPath, QString *encoding, const QgsCoordinateReferenceSystem &crs )
 {
+  errorMessage.clear();
   QgsNewVectorLayerDialog geomDialog( parent );
   geomDialog.setCrs( crs );
+  if ( !initialPath.isEmpty() )
+    geomDialog.setFilename( initialPath );
   if ( geomDialog.exec() == QDialog::Rejected )
   {
     return QString();
   }
 
+  if ( QFile::exists( geomDialog.filename() ) && QMessageBox::warning( parent, tr( "New ShapeFile Layer" ), tr( "The layer already exists. Are you sure you want to overwrite the existing file?" ),
+       QMessageBox::Yes | QMessageBox::Cancel, QMessageBox::Cancel ) != QMessageBox::Yes )
+    return QString();
+
   QgsWkbTypes::Type geometrytype = geomDialog.selectedType();
   QString fileformat = geomDialog.selectedFileFormat();
   QString enc = geomDialog.selectedFileEncoding();
@@ -289,33 +311,35 @@ QString QgsNewVectorLayerDialog::runAndCreateLayer( QWidget *parent, QString *pE
     QgsDebugMsg( QStringLiteral( "ogr provider loaded" ) );
 
     typedef bool ( *createEmptyDataSourceProc )( const QString &, const QString &, const QString &, QgsWkbTypes::Type,
-        const QList< QPair<QString, QString> > &, const QgsCoordinateReferenceSystem & );
+        const QList< QPair<QString, QString> > &, const QgsCoordinateReferenceSystem &, QString & );
     createEmptyDataSourceProc createEmptyDataSource = ( createEmptyDataSourceProc ) cast_to_fptr( myLib->resolve( "createEmptyDataSource" ) );
     if ( createEmptyDataSource )
     {
       if ( geometrytype != QgsWkbTypes::Unknown )
       {
         QgsCoordinateReferenceSystem srs = geomDialog.crs();
-        if ( !createEmptyDataSource( fileName, fileformat, enc, geometrytype, attributes, srs ) )
+        if ( !createEmptyDataSource( fileName, fileformat, enc, geometrytype, attributes, srs, errorMessage ) )
         {
           return QString();
         }
       }
       else
       {
-        QgsDebugMsg( QStringLiteral( "geometry type not recognised" ) );
+        errorMessage = QObject::tr( "Geometry type not recognised" );
+        QgsDebugMsg( errorMessage );
         return QString();
       }
     }
     else
     {
-      QgsDebugMsg( QStringLiteral( "Resolving newEmptyDataSource(...) failed" ) );
+      errorMessage = QObject::tr( "Resolving newEmptyDataSource(...) failed" );
+      QgsDebugMsg( errorMessage );
       return QString();
     }
   }
 
-  if ( pEnc )
-    *pEnc = enc;
+  if ( encoding )
+    *encoding = enc;
 
   return fileName;
 }
@@ -324,3 +348,4 @@ void QgsNewVectorLayerDialog::showHelp()
 {
   QgsHelp::openHelp( QStringLiteral( "managing_data_source/create_layers.html#creating-a-new-shapefile-layer" ) );
 }
+

src/gui/qgsnewvectorlayerdialog.h

@@ -21,8 +21,9 @@
 #include "qgsguiutils.h"
 #include "qgshelp.h"
 
-#include "qgis.h"
+#include "qgswkbtypes.h"
 #include "qgis_gui.h"
+#include "qgis_sip.h"
 
 /**
  * \ingroup gui
@@ -36,10 +37,42 @@ class GUI_EXPORT QgsNewVectorLayerDialog: public QDialog, private Ui::QgsNewVect
 
     /**
      * Runs the dialog and creates a layer matching the dialog parameters.
+     *
+     * If the \a initialPath argument is specified, then the dialog will default to the specified filename.
+     *
      * \returns fileName on success, empty string use aborted, QString() if creation failed
+     *
+     * \deprecated in QGIS 3.4.5 - use execAndCreateLayer() instead.
      */
-    static QString runAndCreateLayer( QWidget *parent = nullptr, QString *enc = nullptr, const QgsCoordinateReferenceSystem &crs = QgsCoordinateReferenceSystem() );
+    Q_DECL_DEPRECATED static QString runAndCreateLayer( QWidget *parent = nullptr, QString *enc = nullptr, const QgsCoordinateReferenceSystem &crs = QgsCoordinateReferenceSystem(),
+        const QString &initialPath = QString() ) SIP_DEPRECATED;
 
+    /**
+     * Runs the dialog and creates a layer matching the dialog parameters.
+     *
+     * If the \a initialPath argument is specified, then the dialog will default to the specified filename.
+     *
+     * Returns a filename if the dialog was accepted, or an empty string if the dialog was canceled.
+     * If the dialog was accepted but an error occurred while creating the file, then the function will
+     * return an empty string and \a errorMessage will contain the error message.
+     *
+     * If \a encoding is specified, it will be set to the encoding of the created file.
+     *
+     * \param errorMessage will be set to any error message encountered during layer creation
+     * \param parent parent widget for dialog
+     * \param initialPath initial file path to show in dialog
+     * \param encoding if specified, will be set to file encoding of created layer
+     * \param crs default layer CRS to show in dialog
+     *
+     * \returns Newly created file name, or an empty string if user canceled or an error occurred.
+     *
+     * \since QGIS 3.4.5
+     */
+    static QString execAndCreateLayer( QString &errorMessage SIP_OUT, QWidget *parent = nullptr, const QString &initialPath = QString(), QString *encoding SIP_OUT = nullptr, const QgsCoordinateReferenceSystem &crs = QgsCoordinateReferenceSystem() );
+
+    /**
+     * New dialog constructor.
+     */
     QgsNewVectorLayerDialog( QWidget *parent SIP_TRANSFERTHIS = nullptr, Qt::WindowFlags fl = QgsGuiUtils::ModalDialogFlags );
     ~QgsNewVectorLayerDialog() override;
     //! Returns the selected geometry type
@@ -50,9 +83,23 @@ class GUI_EXPORT QgsNewVectorLayerDialog: public QDialog, private Ui::QgsNewVect
     QString selectedFileFormat() const;
     //! Returns the file format for storage
     QString selectedFileEncoding() const;
-    //! Returns the name for the new layer
+
+    /**
+     * Returns the name for the new layer
+     *
+     * \see setFilename()
+     */
     QString filename() const;
 
+    /**
+     * Sets the initial file name to show in the dialog.
+     *
+     * \see filename()
+     *
+     * \since QGIS 3.4.5
+     */
+    void setFilename( const QString &filename );
+
     /**
      * Returns the selected CRS for the new layer.
      * \see setCrs()

src/plugins/geometry_checker/qgsgeometrycheckerresulttab.cpp

@@ -261,13 +261,14 @@ bool QgsGeometryCheckerResultTab::exportErrorsDo( const QString &file )
   {
     return false;
   }
-  typedef bool ( *createEmptyDataSourceProc )( const QString &, const QString &, const QString &, QgsWkbTypes::Type, const QList< QPair<QString, QString> > &, const QgsCoordinateReferenceSystem & );
+  typedef bool ( *createEmptyDataSourceProc )( const QString &, const QString &, const QString &, QgsWkbTypes::Type, const QList< QPair<QString, QString> > &, const QgsCoordinateReferenceSystem &, QString & );
   createEmptyDataSourceProc createEmptyDataSource = ( createEmptyDataSourceProc ) cast_to_fptr( ogrLib.resolve( "createEmptyDataSource" ) );
   if ( !createEmptyDataSource )
   {
     return false;
   }
-  if ( !createEmptyDataSource( file, driver, "UTF-8", QgsWkbTypes::Point, attributes, QgsProject::instance()->crs() ) )
+  QString createError;
+  if ( !createEmptyDataSource( file, driver, "UTF-8", QgsWkbTypes::Point, attributes, QgsProject::instance()->crs(), createError ) )
   {
     return false;
   }

src/providers/ogr/qgsogrprovider.cpp

@@ -3183,9 +3183,11 @@ QGISEXTERN bool createEmptyDataSource( const QString &uri,
                                        const QString &encoding,
                                        QgsWkbTypes::Type vectortype,
                                        const QList< QPair<QString, QString> > &attributes,
-                                       const QgsCoordinateReferenceSystem &srs = QgsCoordinateReferenceSystem() )
+                                       const QgsCoordinateReferenceSystem &srs,
+                                       QString &errorMessage )
 {
   QgsDebugMsg( QStringLiteral( "Creating empty vector layer with format: %1" ).arg( format ) );
+  errorMessage.clear();
 
   QgsApplication::registerOgrDrivers();
   OGRSFDriverH driver = OGRGetDriverByName( format.toLatin1() );
@@ -3200,7 +3202,8 @@ QGISEXTERN bool createEmptyDataSource( const QString &uri,
   {
     if ( !uri.endsWith( QLatin1String( ".shp" ), Qt::CaseInsensitive ) )
     {
-      QgsDebugMsg( QStringLiteral( "uri %1 doesn't end with .shp" ).arg( uri ) );
+      errorMessage = QObject::tr( "URI %1 doesn't end with .shp" ).arg( uri );
+      QgsDebugMsg( errorMessage );
       return false;
     }
 
@@ -3212,7 +3215,8 @@ QGISEXTERN bool createEmptyDataSource( const QString &uri,
       QString name = fldIt->first.left( 10 );
       if ( fieldNames.contains( name ) )
       {
-        QgsMessageLog::logMessage( QObject::tr( "Duplicate field (10 significant characters): %1" ).arg( name ), QObject::tr( "OGR" ) );
+        errorMessage = QObject::tr( "Duplicate field (10 significant characters): %1" ).arg( name );
+        QgsMessageLog::logMessage( errorMessage, QObject::tr( "OGR" ) );
         return false;
       }
       fieldNames << name;
@@ -3229,7 +3233,8 @@ QGISEXTERN bool createEmptyDataSource( const QString &uri,
   dataSource.reset( OGR_Dr_CreateDataSource( driver, uri.toUtf8().constData(), nullptr ) );
   if ( !dataSource )
   {
-    QgsMessageLog::logMessage( QObject::tr( "Creating the data source %1 failed: %2" ).arg( uri, QString::fromUtf8( CPLGetLastErrorMsg() ) ), QObject::tr( "OGR" ) );
+    errorMessage = QObject::tr( "Creating the data source %1 failed: %2" ).arg( uri, QString::fromUtf8( CPLGetLastErrorMsg() ) );
+    QgsMessageLog::logMessage( errorMessage, QObject::tr( "OGR" ) );
     return false;
   }
 
@@ -3263,7 +3268,8 @@ QGISEXTERN bool createEmptyDataSource( const QString &uri,
     case QgsWkbTypes::GeometryCollectionZM:
     case QgsWkbTypes::Unknown:
     {
-      QgsMessageLog::logMessage( QObject::tr( "Unknown vector type of %1" ).arg( ( int )( vectortype ) ), QObject::tr( "OGR" ) );
+      errorMessage = QObject::tr( "Unknown vector type of %1" ).arg( static_cast< int >( vectortype ) );
+      QgsMessageLog::logMessage( errorMessage, QObject::tr( "OGR" ) );
       return false;
     }
 
@@ -3292,7 +3298,8 @@ QGISEXTERN bool createEmptyDataSource( const QString &uri,
 
   if ( !layer )
   {
-    QgsMessageLog::logMessage( QObject::tr( "Creation of OGR data source %1 failed: %2" ).arg( uri, QString::fromUtf8( CPLGetLastErrorMsg() ) ), QObject::tr( "OGR" ) );
+    errorMessage = QString::fromUtf8( CPLGetLastErrorMsg() );
+    QgsMessageLog::logMessage( errorMessage, QObject::tr( "OGR" ) );
     return false;
   }