support copy vector layer to browser postgres/spatialite by drag and drop

python/core/qgsmimedatautils.sip

@@ -40,6 +40,14 @@ Returns encoded representation of the object
  :rtype: str
 %End
 
+      QgsVectorLayer *vectorLayer( bool &owner, QString &error ) const;
+%Docstring
+ Get vector layer from uri if possible, otherwise returns 0 and error is set
+ \param owner set to true if caller becomes owner
+ \param error set to error message if cannot get vector
+ :rtype: QgsVectorLayer
+%End
+
       QString layerType;
 %Docstring
 Type of URI. Recognized types: "vector" / "raster" / "plugin" / "custom"

python/core/qgsvectorlayerexporter.sip

@@ -149,11 +149,13 @@ class QgsVectorLayerExporterTask : QgsTask
                                 const QString &uri,
                                 const QString &providerKey,
                                 const QgsCoordinateReferenceSystem &destinationCrs,
-                                QMap<QString, QVariant> *options = 0 );
+                                QMap<QString, QVariant> *options = 0,
+                                bool ownsLayer = false );
 %Docstring
  Constructor for QgsVectorLayerExporterTask. Takes a source ``layer``, destination ``uri``
  and ``providerKey``, and various export related parameters such as destination CRS
  and export ``options``.
+ \param ownsLayer take ownership of layer and deletes it after export
 %End
 
     static QgsVectorLayerExporterTask *withLayerOwnership( QgsVectorLayer *layer /Transfer/,

src/core/qgsmimedatautils.cpp

@@ -27,7 +27,6 @@
 
 static const char *QGIS_URILIST_MIMETYPE = "application/x-vnd.qgis.qgis.uri";
 
-
 QgsMimeDataUtils::Uri::Uri()
 {
 }
@@ -66,6 +65,41 @@ QString QgsMimeDataUtils::Uri::data() const
   return encode( QStringList() << layerType << providerKey << name << uri << encode( supportedCrs ) << encode( supportedFormats ) );
 }
 
+QgsVectorLayer *QgsMimeDataUtils::Uri::vectorLayer( bool &owner, QString &error ) const
+{
+  owner = false;
+  if ( layerType != QLatin1String( "vector" ) )
+  {
+    error = QObject::tr( "%1: Not a vector layer." ).arg( name );
+    return nullptr;
+  }
+  if ( providerKey == QLatin1String( "memory" ) )
+  {
+    QUrl url = QUrl::fromEncoded( uri.toUtf8() );
+    if ( !url.hasQueryItem( QStringLiteral( "pid" ) ) || !url.hasQueryItem( QStringLiteral( "layerid" ) ) )
+    {
+      error = QObject::tr( "Memory layer uri does not contain process or layer id." );
+      return nullptr;
+    }
+    qint64 pid = url.queryItemValue( QStringLiteral( "pid" ) ).toLongLong();
+    if ( pid != QCoreApplication::applicationPid() )
+    {
+      error = QObject::tr( "Memory layer from another QGIS instance." );
+      return nullptr;
+    }
+    QString layerId = url.queryItemValue( QStringLiteral( "layerid" ) );
+    QgsVectorLayer *vectorLayer = qobject_cast< QgsVectorLayer *>( QgsProject::instance()->mapLayer( layerId ) );
+    if ( !vectorLayer )
+    {
+      error = QObject::tr( "Cannot get memory layer." );
+      return nullptr;
+    }
+    return vectorLayer;
+  }
+  owner = true;
+  return new QgsVectorLayer( uri, name, providerKey );
+}
+
 // -----
 
 bool QgsMimeDataUtils::isUriList( const QMimeData *data )
@@ -119,6 +153,13 @@ static void _addLayerTreeNodeToUriList( QgsLayerTreeNode *node, QgsMimeDataUtils
     if ( layer->type() == QgsMapLayer::VectorLayer )
     {
       uri.layerType = QStringLiteral( "vector" );
+      if ( uri.providerKey == QStringLiteral( "memory" ) )
+      {
+        QUrl url = QUrl::fromEncoded( uri.uri.toUtf8() );
+        url.addQueryItem( QStringLiteral( "pid" ), QString::number( QCoreApplication::applicationPid() ) );
+        url.addQueryItem( QStringLiteral( "layerid" ), layer->id() );
+        uri.uri = QString( url.toEncoded() );
+      }
     }
     else if ( layer->type() == QgsMapLayer::RasterLayer )
     {

src/core/qgsmimedatautils.h

@@ -22,6 +22,7 @@
 
 class QgsLayerItem;
 class QgsLayerTreeNode;
+class QgsVectorLayer;
 
 /** \ingroup core
  * \class QgsMimeDataUtils
@@ -44,6 +45,12 @@ class CORE_EXPORT QgsMimeDataUtils
       //! Returns encoded representation of the object
       QString data() const;
 
+      /** Get vector layer from uri if possible, otherwise returns 0 and error is set
+       * \param owner set to true if caller becomes owner
+       * \param error set to error message if cannot get vector
+       */
+      QgsVectorLayer *vectorLayer( bool &owner, QString &error ) const;
+
       //! Type of URI. Recognized types: "vector" / "raster" / "plugin" / "custom"
       QString layerType;
       //! For "vector" / "raster" type: provider id.

src/core/qgsvectorlayerexporter.cpp

@@ -456,9 +456,10 @@ QgsVectorLayerExporter::exportLayer( QgsVectorLayer *layer,
 // QgsVectorLayerExporterTask
 //
 
-QgsVectorLayerExporterTask::QgsVectorLayerExporterTask( QgsVectorLayer *layer, const QString &uri, const QString &providerKey, const QgsCoordinateReferenceSystem &destinationCrs, QMap<QString, QVariant> *options )
+QgsVectorLayerExporterTask::QgsVectorLayerExporterTask( QgsVectorLayer *layer, const QString &uri, const QString &providerKey, const QgsCoordinateReferenceSystem &destinationCrs, QMap<QString, QVariant> *options, bool ownsLayer )
   : QgsTask( tr( "Exporting %1" ).arg( layer->name() ), QgsTask::CanCancel )
   , mLayer( layer )
+  , mOwnsLayer( ownsLayer )
   , mDestUri( uri )
   , mDestProviderKey( providerKey )
   , mDestCrs( destinationCrs )

src/core/qgsvectorlayerexporter.h

@@ -189,12 +189,14 @@ class CORE_EXPORT QgsVectorLayerExporterTask : public QgsTask
      * Constructor for QgsVectorLayerExporterTask. Takes a source \a layer, destination \a uri
      * and \a providerKey, and various export related parameters such as destination CRS
      * and export \a options.
+     * \param ownsLayer take ownership of layer and deletes it after export
     */
     QgsVectorLayerExporterTask( QgsVectorLayer *layer,
                                 const QString &uri,
                                 const QString &providerKey,
                                 const QgsCoordinateReferenceSystem &destinationCrs,
-                                QMap<QString, QVariant> *options = nullptr );
+                                QMap<QString, QVariant> *options = nullptr,
+                                bool ownsLayer = false );
 
     /**
      * Creates a new QgsVectorLayerExporterTask which has ownership over a source \a layer.

src/providers/postgres/qgspostgresdataitems.cpp

@@ -201,16 +201,17 @@ bool QgsPGConnectionItem::handleDrop( const QMimeData *data, const QString &toSc
   QgsMimeDataUtils::UriList lst = QgsMimeDataUtils::decodeUriList( data );
   Q_FOREACH ( const QgsMimeDataUtils::Uri &u, lst )
   {
-    if ( u.layerType != QLatin1String( "vector" ) )
+    // open the source layer
+    bool owner;
+    QString error;
+    QgsVectorLayer *srcLayer = u.vectorLayer( owner, error );
+    if ( !srcLayer )
     {
-      importResults.append( tr( "%1: Not a vector layer!" ).arg( u.name ) );
+      importResults.append( tr( "%1: %2" ).arg( u.name ).arg( error ) );
-      hasError = true; // only vectors can be imported
+      hasError = true;
       continue;
     }
 
-    // open the source layer
-    QgsVectorLayer *srcLayer = new QgsVectorLayer( u.uri, u.name, u.providerKey );
-
     if ( srcLayer->isValid() )
     {
       uri.setDataSource( QString(), u.name,  srcLayer->geometryType() != QgsWkbTypes::NullGeometry ? QStringLiteral( "geom" ) : QString() );
@@ -221,7 +222,7 @@ bool QgsPGConnectionItem::handleDrop( const QMimeData *data, const QString &toSc
         uri.setSchema( toSchema );
       }
 
-      std::unique_ptr< QgsVectorLayerExporterTask > exportTask( QgsVectorLayerExporterTask::withLayerOwnership( srcLayer, uri.uri( false ), QStringLiteral( "postgres" ), srcLayer->crs() ) );
+      std::unique_ptr< QgsVectorLayerExporterTask > exportTask( new QgsVectorLayerExporterTask( srcLayer, uri.uri( false ), QStringLiteral( "postgres" ), srcLayer->crs(), nullptr, owner ) );
 
       // when export is successful:
       connect( exportTask.get(), &QgsVectorLayerExporterTask::exportComplete, this, [ = ]()

src/providers/spatialite/qgsspatialitedataitems.cpp

@@ -205,22 +205,23 @@ bool QgsSLConnectionItem::handleDrop( const QMimeData *data, Qt::DropAction )
   QgsMimeDataUtils::UriList lst = QgsMimeDataUtils::decodeUriList( data );
   Q_FOREACH ( const QgsMimeDataUtils::Uri &u, lst )
   {
-    if ( u.layerType != QLatin1String( "vector" ) )
+    // open the source layer
+    bool owner;
+    QString error;
+    QgsVectorLayer *srcLayer = u.vectorLayer( owner, error );
+    if ( !srcLayer )
     {
-      importResults.append( tr( "%1: Not a vector layer!" ).arg( u.name ) );
+      importResults.append( tr( "%1: %2" ).arg( u.name ).arg( error ) );
-      hasError = true; // only vectors can be imported
+      hasError = true;
       continue;
     }
 
-    // open the source layer
-    QgsVectorLayer *srcLayer = new QgsVectorLayer( u.uri, u.name, u.providerKey );
-
     if ( srcLayer->isValid() )
     {
       destUri.setDataSource( QString(), u.name, srcLayer->geometryType() != QgsWkbTypes::NullGeometry ? QStringLiteral( "geom" ) : QString() );
       QgsDebugMsg( "URI " + destUri.uri() );
 
-      std::unique_ptr< QgsVectorLayerExporterTask > exportTask( QgsVectorLayerExporterTask::withLayerOwnership( srcLayer, destUri.uri(), QStringLiteral( "spatialite" ), srcLayer->crs() ) );
+      std::unique_ptr< QgsVectorLayerExporterTask > exportTask( new QgsVectorLayerExporterTask( srcLayer, destUri.uri(), QStringLiteral( "spatialite" ), srcLayer->crs(), nullptr, owner ) );
 
       // when export is successful:
       connect( exportTask.get(), &QgsVectorLayerExporterTask::exportComplete, this, [ = ]()