[feature] Geopackage handle drops in the browser

It is now possible to drag and drop from any vector
layer onto a gpkg node layer and import a layer.

Overwrites are protected by a confirmation dialog.

src/providers/ogr/qgsgeopackagedataitems.cpp

@@ -21,6 +21,8 @@
 #include "qgsvectorlayer.h"
 #include "qgsrasterlayer.h"
 #include "qgsnewgeopackagelayerdialog.h"
+#include "qgsmessageoutput.h"
+#include "qgsvectorlayerexporter.h"
 
 #include <QAction>
 #include <QMessageBox>
@@ -268,6 +270,115 @@ QList<QAction *> QgsGeoPackageConnectionItem::actions()
 }
 #endif
 
+
+
+bool QgsGeoPackageConnectionItem::handleDrop( const QMimeData *data, Qt::DropAction )
+{
+
+  if ( !QgsMimeDataUtils::isUriList( data ) )
+    return false;
+
+  // TODO: probably should show a GUI with settings etc
+  QString uri;
+
+  QStringList importResults;
+  bool hasError = false;
+
+  QgsMimeDataUtils::UriList lst = QgsMimeDataUtils::decodeUriList( data );
+  Q_FOREACH ( const QgsMimeDataUtils::Uri &u, lst )
+  {
+    if ( u.layerType == QStringLiteral( "vector" ) )
+    {
+      // open the source layer
+      bool owner;
+      QString error;
+      QgsVectorLayer *srcLayer = u.vectorLayer( owner, error );
+      if ( !srcLayer )
+      {
+        importResults.append( tr( "%1: %2" ).arg( u.name ).arg( error ) );
+        hasError = true;
+        continue;
+      }
+
+      if ( srcLayer->isValid() )
+      {
+        uri = mPath;
+        QgsDebugMsgLevel( "URI " + uri, 3 );
+
+        // check if the destination layer already exists
+        bool exists = false;
+        // Q_FOREACH won't detach ...
+        for ( const auto child : children() )
+        {
+          if ( child->name() == u.name )
+          {
+            exists = true;
+          }
+        }
+        if ( ! exists || QMessageBox::question( nullptr, tr( "Overwrite Layer" ),
+                                                tr( "Destination layer <b>%1</b> already exists. Do you want to overwrite it?" ).arg( u.name ), QMessageBox::Yes |  QMessageBox::No ) == QMessageBox::Yes )
+        {
+
+          std::unique_ptr< QMap<QString, QVariant> > options( new QMap<QString, QVariant> );
+          options->insert( QStringLiteral( "driverName" ), QStringLiteral( "GPKG" ) );
+          options->insert( QStringLiteral( "update" ), true );
+          options->insert( QStringLiteral( "overwrite" ), true );
+          options->insert( QStringLiteral( "layerName" ), u.name );
+
+          std::unique_ptr< QgsVectorLayerExporterTask > exportTask( new QgsVectorLayerExporterTask( srcLayer, uri, QStringLiteral( "ogr" ), srcLayer->crs(), options.get(), owner ) );
+
+          // when export is successful:
+          connect( exportTask.get(), &QgsVectorLayerExporterTask::exportComplete, this, [ = ]()
+          {
+            // this is gross - TODO - find a way to get access to messageBar from data items
+            QMessageBox::information( nullptr, tr( "Import to GeoPackage database" ), tr( "Import was successful." ) );
+            refreshConnections();
+          } );
+
+          // when an error occurs:
+          connect( exportTask.get(), &QgsVectorLayerExporterTask::errorOccurred, this, [ = ]( int error, const QString & errorMessage )
+          {
+            if ( error != QgsVectorLayerExporter::ErrUserCanceled )
+            {
+              QgsMessageOutput *output = QgsMessageOutput::createMessageOutput();
+              output->setTitle( tr( "Import to GeoPackage database" ) );
+              output->setMessage( tr( "Failed to import some layers!\n\n" ) + errorMessage, QgsMessageOutput::MessageText );
+              output->showMessage();
+            }
+          } );
+
+          QgsApplication::taskManager()->addTask( exportTask.release() );
+        }
+      }
+      else
+      {
+        importResults.append( tr( "%1: Not a valid layer!" ).arg( u.name ) );
+        hasError = true;
+      }
+    }
+    else
+    {
+      // TODO: implemnent raster import
+      QgsMessageOutput *output = QgsMessageOutput::createMessageOutput();
+      output->setTitle( tr( "Import to GeoPackage database faile" ) );
+      output->setMessage( tr( "Failed to import some layers!\n\n" ) + QStringLiteral( "Raster import is not yet implemented!\n" ), QgsMessageOutput::MessageText );
+      output->showMessage();
+    }
+
+  }
+
+  if ( hasError )
+  {
+    QgsMessageOutput *output = QgsMessageOutput::createMessageOutput();
+    output->setTitle( tr( "Import to GeoPackage database" ) );
+    output->setMessage( tr( "Failed to import some layers!\n\n" ) + importResults.join( QStringLiteral( "\n" ) ), QgsMessageOutput::MessageText );
+    output->showMessage();
+  }
+
+  return true;
+}
+
+
 QgsLayerItem::LayerType QgsGeoPackageConnectionItem::layerTypeFromDb( const QString &geometryType )
 {
   if ( geometryType.contains( QStringLiteral( "Point" ), Qt::CaseInsensitive ) )

src/providers/ogr/qgsgeopackagedataitems.h

@@ -67,7 +67,7 @@ class QgsGeoPackageConnectionItem : public QgsDataCollectionItem
 #endif
 
     virtual bool acceptDrop() override { return true; }
-    //virtual bool handleDrop( const QMimeData *data, Qt::DropAction action ) override;
+    virtual bool handleDrop( const QMimeData *data, Qt::DropAction action ) override;
 
     //! Return the layer type from \a geometryType
     static QgsLayerItem::LayerType layerTypeFromDb( const QString &geometryType );