A few UX enhancements for error reporting on GPKGs

This fixes #36574 by showing an error in the data
items when the layer cannot be opened.

In the same way, similar errors now bubble up
to the message bar from data source select dialog.

python/gui/auto_generated/qgsabstractdatasourcewidget.sip.in

@@ -138,6 +138,13 @@ Emitted when a progress dialog is shown by the provider dialog
 Emitted when the ok/add buttons should be enabled/disabled
 %End
 
+    void pushMessage( const QString &title, const QString &message, const Qgis::MessageLevel level = Qgis::MessageLevel::Info );
+%Docstring
+Emitted when a ``message`` with ``title`` and ``level`` must be shown to the user using the parent visible message bar
+
+.. versionadded:: 3.14
+%End
+
 
   protected:
 

src/app/qgisapp.cpp

@@ -15865,7 +15865,7 @@ void QgisApp::onLayerError( const QString &msg )
 
   Q_ASSERT( layer );
 
-  mInfoBar->pushCritical( tr( "Layer %1" ).arg( layer->name() ), msg );
+  visibleMessageBar()->pushCritical( tr( "Layer %1" ).arg( layer->name() ), msg );
 }
 
 bool QgisApp::gestureEvent( QGestureEvent *event )

src/core/providers/ogr/qgsgeopackagedataitems.cpp

@@ -112,6 +112,8 @@ QgsGeoPackageCollectionItem::QgsGeoPackageCollectionItem( QgsDataItem *parent, c
 QVector<QgsDataItem *> QgsGeoPackageCollectionItem::createChildren()
 {
   QVector<QgsDataItem *> children;
+  try
+  {
     const auto layers = QgsOgrLayerItem::subLayers( mPath.remove( QLatin1String( "gpkg:/" ) ), QStringLiteral( "GPKG" ) );
     for ( const QgsOgrDbLayerInfo *info : layers )
     {
@@ -135,6 +137,11 @@ QVector<QgsDataItem *> QgsGeoPackageCollectionItem::createChildren()
         children.append( new QgsProjectItem( this, projectName, QgsGeoPackageProjectStorage::encodeUri( projectUri ) ) );
       }
     }
+  }
+  catch ( QgsOgrLayerNotValidException &ex )
+  {
+    children.append( new QgsErrorItem( this, ex.what(), mPath + "/error" ) );
+  }
   return children;
 }
 

src/core/providers/ogr/qgsogrdataitems.cpp

@@ -107,11 +107,7 @@ QList<QgsOgrDbLayerInfo *> QgsOgrLayerItem::subLayers( const QString &path, cons
   // Vector layers
   const QgsVectorLayer::LayerOptions layerOptions { QgsProject::instance()->transformContext() };
   QgsVectorLayer layer( path, QStringLiteral( "ogr_tmp" ), QStringLiteral( "ogr" ), layerOptions );
-  if ( ! layer.isValid( ) )
+  if ( layer.isValid( ) )
-  {
-    QgsDebugMsgLevel( QStringLiteral( "Layer is not a valid %1 Vector layer %2" ).arg( path ), 3 );
-  }
-  else
   {
     // Collect mixed-geom layers
     QMultiMap<int, QStringList> subLayersMap;
@@ -188,6 +184,7 @@ QList<QgsOgrDbLayerInfo *> QgsOgrLayerItem::subLayers( const QString &path, cons
       }
     }
   }
+
   // Raster layers
   QgsRasterLayer::LayerOptions options;
   options.loadDefaultStyle = false;
@@ -200,7 +197,7 @@ QList<QgsOgrDbLayerInfo *> QgsOgrLayerItem::subLayers( const QString &path, cons
       // Split on ':' since this is what comes out from the provider
       QStringList pieces = uri.split( ':' );
       QString name = pieces.value( pieces.length() - 1 );
-      QgsDebugMsgLevel( QStringLiteral( "Adding GeoPackage Raster item %1 %2 %3" ).arg( name, uri ), 3 );
+      QgsDebugMsgLevel( QStringLiteral( "Adding GeoPackage Raster item %1 %2" ).arg( name, uri ), 3 );
       children.append( new QgsOgrDbLayerInfo( path, uri, name, QString(), QStringLiteral( "Raster" ), QgsLayerItem::LayerType::Raster ) );
     }
   }
@@ -238,6 +235,24 @@ QList<QgsOgrDbLayerInfo *> QgsOgrLayerItem::subLayers( const QString &path, cons
       children.append( new QgsOgrDbLayerInfo( path, uri, name, QString(), QStringLiteral( "Raster" ), QgsLayerItem::LayerType::Raster ) );
     }
   }
+
+  // There were problems in reading the file: throw
+  if ( ! layer.isValid() && ! rlayer.isValid() )
+  {
+    QString errorMessage;
+    // If it is file based and the file exists, there might be a permission error, let's change
+    // the message to give the user a hint about this possiblity.
+    if ( QFile::exists( path ) )
+    {
+      errorMessage = tr( "Error opening file, check file and directory permissions on\n%1" ).arg( path );
+    }
+    else
+    {
+      errorMessage = tr( "Layer is not valid (%1)" ).arg( path );
+    }
+    throw QgsOgrLayerNotValidException( errorMessage );
+  }
+
   return children;
 }
 

src/core/providers/ogr/qgsogrdataitems.h

@@ -55,6 +55,20 @@ class CORE_EXPORT QgsOgrDbLayerInfo
     QgsLayerItem::LayerType mLayerType = QgsLayerItem::LayerType::NoType;
 };
 
+/**
+ * The QgsOgrLayerException class is thrown by QgsOgrLayerItem when the layer is not valid
+ */
+class CORE_EXPORT QgsOgrLayerNotValidException: public QgsException
+{
+  public:
+
+    /**
+     * Constructor for QgsOgrLayerNotValidException, with the specified error \a message.
+     */
+    QgsOgrLayerNotValidException( const QString &message )
+      : QgsException( message )
+    {}
+};
 
 class CORE_EXPORT QgsOgrLayerItem final: public QgsLayerItem
 {
@@ -63,7 +77,11 @@ class CORE_EXPORT QgsOgrLayerItem final: public QgsLayerItem
     QgsOgrLayerItem( QgsDataItem *parent, const QString &name, const QString &path, const QString &uri, LayerType layerType, bool isSubLayer = false );
 
     QString layerName() const override;
-    //! Retrieve sub layers from a DB ogr layer \a path with the specified \a driver
+
+    /**
+     * Retrieve sub layers from a DB ogr layer \a path with the specified \a driver
+     * If the layer is not valid, throw a std::exception
+     */
     static QList<QgsOgrDbLayerInfo *> subLayers( const QString &path, const QString &driver );
     //! Returns a LayerType from a geometry type string
     static QgsLayerItem::LayerType layerTypeFromDb( const QString &geometryType );

src/gui/ogr/qgsvectorlayersaveasdialog.cpp

@@ -358,6 +358,8 @@ void QgsVectorLayerSaveAsDialog::accept()
     }
   }
   else if ( mActionOnExistingFile == QgsVectorFileWriter::CreateOrOverwriteFile )
+  {
+    try
     {
       const QList<QgsOgrDbLayerInfo *> subLayers = QgsOgrLayerItem::subLayers( filename(), format() );
       QStringList layerList;
@@ -379,6 +381,14 @@ void QgsVectorLayerSaveAsDialog::accept()
           return;
       }
     }
+    catch ( QgsOgrLayerNotValidException &ex )
+    {
+      QMessageBox::critical( this,
+                             tr( "Save Vector Layer As" ),
+                             tr( "Error opening destination file: %1" ).arg( ex.what() ) );
+      return;
+    }
+  }
 
   QgsSettings settings;
   settings.setValue( QStringLiteral( "UI/lastVectorFileFilterDir" ), QFileInfo( filename() ).absolutePath() );

src/gui/providers/ogr/qgsogrdbsourceselect.cpp

@@ -332,6 +332,9 @@ void QgsOgrDbSourceSelect::btnConnect_clicked()
   QgsOgrDbConnection conn( subKey, ogrDriverName() );
 
   mPath = conn.path();
+
+  try
+  {
     const QList<QgsOgrDbLayerInfo *> layers = QgsOgrLayerItem::subLayers( mPath, ogrDriverName() );
 
     QModelIndex rootItemIndex = mTableModel.indexFromItem( mTableModel.invisibleRootItem() );
@@ -368,6 +371,11 @@ void QgsOgrDbSourceSelect::btnConnect_clicked()
     QgsOgrDbConnection::setSelectedConnection( subKey, ogrDriverName() );
     qDeleteAll( layers );
   }
+  catch ( QgsOgrLayerNotValidException &ex )
+  {
+    pushMessage( tr( "Error opening layer" ), ex.what(), Qgis::MessageLevel::Critical );
+  }
+}
 
 
 void QgsOgrDbSourceSelect::setSql( const QModelIndex &index )

src/gui/qgsabstractdatasourcewidget.h

@@ -142,6 +142,12 @@ class GUI_EXPORT QgsAbstractDataSourceWidget : public QDialog
     //! Emitted when the ok/add buttons should be enabled/disabled
     void enableButtons( bool enable );
 
+    /**
+     * Emitted when a \a message with \a title and \a level must be shown to the user using the parent visible message bar
+     * \since QGIS 3.14
+     */
+    void pushMessage( const QString &title, const QString &message, const Qgis::MessageLevel level = Qgis::MessageLevel::Info );
+
 
   protected:
 

src/gui/qgsdatasourcemanagerdialog.cpp

@@ -166,10 +166,10 @@ void QgsDataSourceManagerDialog::addProviderDialog( QgsAbstractDataSourceWidget
 void QgsDataSourceManagerDialog::makeConnections( QgsAbstractDataSourceWidget *dlg, const QString &providerKey )
 {
   // DB
-  connect( dlg, SIGNAL( addDatabaseLayers( QStringList const &, QString const & ) ),
+  connect( dlg, &QgsAbstractDataSourceWidget::addDatabaseLayers,
-           this, SIGNAL( addDatabaseLayers( QStringList const &, QString const & ) ) );
+           this, &QgsDataSourceManagerDialog::addDatabaseLayers );
-  connect( dlg, SIGNAL( progressMessage( QString ) ),
+  connect( dlg, &QgsAbstractDataSourceWidget::progressMessage,
-           this, SIGNAL( showStatusMessage( QString ) ) );
+           this, &QgsDataSourceManagerDialog::showStatusMessage );
   // Vector
   connect( dlg, &QgsAbstractDataSourceWidget::addVectorLayer, this, [ = ]( const QString & vectorLayerPath, const QString & baseName, const QString & specifiedProvider )
   {
@@ -179,20 +179,29 @@ void QgsDataSourceManagerDialog::makeConnections( QgsAbstractDataSourceWidget *d
          );
   connect( dlg, &QgsAbstractDataSourceWidget::addVectorLayers,
            this, &QgsDataSourceManagerDialog::vectorLayersAdded );
-  connect( dlg, SIGNAL( connectionsChanged() ), this, SIGNAL( connectionsChanged() ) );
+  connect( dlg, &QgsAbstractDataSourceWidget::connectionsChanged, this, &QgsDataSourceManagerDialog::connectionsChanged );
   // Raster
-  connect( dlg, SIGNAL( addRasterLayer( QString const &, QString const &, QString const & ) ),
+  connect( dlg, &QgsAbstractDataSourceWidget::addRasterLayer,
-           this, SIGNAL( addRasterLayer( QString const &, QString const &, QString const & ) ) );
+           this, [ = ]( const QString & uri, const QString & baseName, const QString & providerKey )
+  {
+    addRasterLayer( uri, baseName, providerKey );
+  } );
   // Mesh
   connect( dlg, &QgsAbstractDataSourceWidget::addMeshLayer, this, &QgsDataSourceManagerDialog::addMeshLayer );
   // Vector tile
   connect( dlg, &QgsAbstractDataSourceWidget::addVectorTileLayer, this, &QgsDataSourceManagerDialog::addVectorTileLayer );
   // Virtual
-  connect( dlg, SIGNAL( replaceVectorLayer( QString, QString, QString, QString ) ),
+  connect( dlg, &QgsAbstractDataSourceWidget::replaceVectorLayer,
-           this, SIGNAL( replaceSelectedVectorLayer( QString, QString, QString, QString ) ) );
+           this, &QgsDataSourceManagerDialog::replaceSelectedVectorLayer );
   // Common
-  connect( dlg, SIGNAL( connectionsChanged() ), this, SIGNAL( connectionsChanged() ) );
+  connect( dlg, &QgsAbstractDataSourceWidget::connectionsChanged, this, &QgsDataSourceManagerDialog::connectionsChanged );
-  connect( this, SIGNAL( providerDialogsRefreshRequested() ), dlg, SLOT( refresh() ) );
+  connect( this, &QgsDataSourceManagerDialog::providerDialogsRefreshRequested, dlg, &QgsAbstractDataSourceWidget::refresh );
+
+  // Message
+  connect( dlg, &QgsAbstractDataSourceWidget::pushMessage, this, [ = ]( const QString & title, const QString & message, const Qgis::MessageLevel level )
+  {
+    mMessageBar->pushMessage( title, message, level );
+  } );
 }
 
 void QgsDataSourceManagerDialog::showEvent( QShowEvent *e )