load and save metadata to a QMD file

python/core/qgsmaplayer.sip

@@ -55,6 +55,12 @@ This is the base class for all map layer types (vector, raster).
       PluginLayer
     };
 
+    enum PropertyType
+    {
+      Style,
+      Metadata,
+    };
+
     QgsMapLayer( QgsMapLayer::LayerType type = VectorLayer, const QString &name = QString(), const QString &source = QString() );
 %Docstring
 Constructor for QgsMapLayer
@@ -80,6 +86,15 @@ is still unique.
     QgsMapLayer::LayerType type() const;
 %Docstring
 Returns the type of the layer.
+%End
+
+    static QString extensionPropertyType( PropertyType type );
+%Docstring
+Returns the extension of a Property.
+
+:return: The extension
+
+.. versionadded:: 3.0
 %End
 
     QString id() const;
@@ -545,6 +560,118 @@ Sets layer's spatial reference system
 %Docstring
 A convenience function to capitalize and format a layer ``name``.
 
+.. versionadded:: 3.0
+%End
+
+    virtual QString metadataUri() const;
+%Docstring
+Retrieve the metadata URI for this layer
+(either as a .qmd file on disk or as a
+record in the users style table in their personal qgis.db)
+
+:return: a QString with the metadata file name
+
+.. versionadded:: 3.0
+%End
+
+    void exportNamedMetadata( QDomDocument &doc, QString &errorMsg ) const;
+%Docstring
+Export the current metadata of this layer as named metadata in a QDomDocument
+
+:param doc: the target QDomDocument
+:param errorMsg: this QString will be initialized on error
+
+.. versionadded:: 3.0
+%End
+
+    virtual QString saveDefaultMetadata( bool &resultFlag /Out/ );
+%Docstring
+Save the current metadata of this layer as the default metadata
+(either as a .qmd file on disk or as a
+record in the users style table in their personal qgis.db)
+
+:param resultFlag: a reference to a flag that will be set to false if
+we did not manage to save the default metadata.
+
+:return: a QString with any status messages
+
+.. versionadded:: 3.0
+%End
+
+    QString saveNamedMetadata( const QString &uri, bool &resultFlag );
+%Docstring
+Save the current metadata of this layer as a named metadata
+(either as a .qmd file on disk or as a
+record in the users style table in their personal qgis.db)
+
+:param uri: the file name or other URI for the
+metadata file. First an attempt will be made to see if this
+is a file and save to that, if that fails the qgis.db metadata
+table will be used to create a metadata entry who's
+key matches the URI.
+:param resultFlag: a reference to a flag that will be set to false if
+we did not manage to save the default metadata.
+
+:return: a QString with any status messages
+
+.. versionadded:: 3.0
+%End
+
+    virtual QString loadNamedMetadata( const QString &uri, bool &resultFlag /Out/ );
+%Docstring
+Retrieve a named metadata for this layer if one
+exists (either as a .qmd file on disk or as a
+record in the users style table in their personal qgis.db)
+
+:param uri: - the file name or other URI for the
+metadata file. First an attempt will be made to see if this
+is a file and load that, if that fails the qgis.db metadata
+table will be consulted to see if there is a metadata who's
+key matches the URI.
+:param resultFlag: a reference to a flag that will be set to false if
+we did not manage to load the default metadata.
+
+:return: a QString with any status messages
+
+.. versionadded:: 3.0
+%End
+
+    QString loadDefaultMetadata( bool &resultFlag );
+%Docstring
+Retrieve the default metadata for this layer if one
+exists (either as a .qmd file on disk or as a
+record in the users metadata table in their personal qgis.db)
+
+:param resultFlag: a reference to a flag that will be set to false if
+we did not manage to load the default metadata.
+
+:return: a QString with any status messages
+
+.. versionadded:: 3.0
+%End
+
+    bool loadNamedMetadataFromDatabase( const QString &db, const QString &uri, QString &qmd );
+%Docstring
+Retrieve a named metadata for this layer from a sqlite database.
+
+:param db: path to sqlite database
+:param uri: uri for table
+:param qmd: will be set to QMD xml metadata content from database
+
+:return: true if style was successfully loaded
+
+.. versionadded:: 3.0
+%End
+
+    bool importNamedMetadata( QDomDocument &document, QString &errorMessage );
+%Docstring
+Import the metadata of this layer from a QDomDocument
+
+:param document: source QDomDocument
+:param errorMessage: this QString will be initialized on error
+
+:return: true on success
+
 .. versionadded:: 3.0
 %End
 

python/gui/qgsmetadatawidget.sip

@@ -46,6 +46,11 @@ If the CRS is updated.
     void acceptMetadata();
 %Docstring
 Saves the metadata to the layer.
+%End
+
+    virtual void setMetadata( const QgsLayerMetadata &metadata );
+%Docstring
+Sets the layer's ``metadata`` store.
 %End
 
     static QMap<QString, QString> parseLanguages();

src/app/qgisapp.cpp

@@ -4321,6 +4321,7 @@ bool QgisApp::addVectorLayers( const QStringList &layerQStringList, const QStrin
   {
     bool ok;
     l->loadDefaultStyle( ok );
+    l->loadDefaultMetadata( ok );
   }
   activateDeactivateLayerRelatedActions( activeLayer() );
 
@@ -4747,6 +4748,7 @@ void QgisApp::askUserForOGRSublayers( QgsVectorLayer *layer )
     {
       bool ok;
       l->loadDefaultStyle( ok );
+      l->loadDefaultMetadata( ok );
       if ( addToGroup )
         group->addLayer( l );
     }
@@ -4839,6 +4841,7 @@ void QgisApp::addDatabaseLayers( QStringList const &layerPathList, QString const
   {
     bool ok;
     l->loadDefaultStyle( ok );
+    l->loadDefaultMetadata( ok );
   }
 
   // draw the map
@@ -10249,6 +10252,7 @@ QgsVectorLayer *QgisApp::addVectorLayer( const QString &vectorLayerPath, const Q
       QgsProject::instance()->addMapLayers( myList );
       bool ok;
       layer->loadDefaultStyle( ok );
+      layer->loadDefaultMetadata( ok );
     }
   }
   else

src/app/qgsrasterlayerproperties.cpp

@@ -104,16 +104,26 @@ QgsRasterLayerProperties::QgsRasterLayerProperties( QgsMapLayer *lyr, QgsMapCanv
 
   connect( buttonBox, &QDialogButtonBox::helpRequested, this, &QgsRasterLayerProperties::showHelp );
 
-  QPushButton *b = new QPushButton( tr( "Style" ) );
-  QMenu *m = new QMenu( this );
-  m->addAction( tr( "Load Style..." ), this, SLOT( loadStyle_clicked() ) );
-  m->addAction( tr( "Save Style..." ), this, SLOT( saveStyleAs_clicked() ) );
-  m->addSeparator();
-  m->addAction( tr( "Save as Default" ), this, SLOT( saveDefaultStyle_clicked() ) );
-  m->addAction( tr( "Restore Default" ), this, SLOT( loadDefaultStyle_clicked() ) );
-  b->setMenu( m );
-  connect( m, &QMenu::aboutToShow, this, &QgsRasterLayerProperties::aboutToShowStyleMenu );
-  buttonBox->addButton( b, QDialogButtonBox::ResetRole );
+  mBtnStyle = new QPushButton( tr( "Style" ) );
+  QMenu *menuStyle = new QMenu( this );
+  menuStyle->addAction( tr( "Load Style..." ), this, SLOT( loadStyle_clicked() ) );
+  menuStyle->addAction( tr( "Save Style..." ), this, SLOT( saveStyleAs_clicked() ) );
+  menuStyle->addSeparator();
+  menuStyle->addAction( tr( "Save as Default" ), this, SLOT( saveDefaultStyle_clicked() ) );
+  menuStyle->addAction( tr( "Restore Default" ), this, SLOT( loadDefaultStyle_clicked() ) );
+  mBtnStyle->setMenu( menuStyle );
+  connect( menuStyle, &QMenu::aboutToShow, this, &QgsRasterLayerProperties::aboutToShowStyleMenu );
+  buttonBox->addButton( mBtnStyle, QDialogButtonBox::ResetRole );
+
+  mBtnMetadata = new QPushButton( tr( "Metadata" ), this );
+  QMenu *menuMetadata = new QMenu( this );
+  mActionLoadMetadata = menuMetadata->addAction( tr( "Load Metadata" ), this, SLOT( loadMetadata() ) );
+  mActionSaveMetadataAs = menuMetadata->addAction( tr( "Save Metadata" ), this, SLOT( saveMetadataAs() ) );
+  menuMetadata->addSeparator();
+  menuMetadata->addAction( tr( "Save as Default" ), this, SLOT( saveDefaultMetadata() ) );
+  menuMetadata->addAction( tr( "Restore Default" ), this, SLOT( loadDefaultMetadata() ) );
+  mBtnMetadata->setMenu( menuMetadata );
+  buttonBox->addButton( mBtnMetadata, QDialogButtonBox::ResetRole );
 
   connect( lyr->styleManager(), &QgsMapLayerStyleManager::currentStyleChanged, this, &QgsRasterLayerProperties::syncToLayer );
 
@@ -436,6 +446,7 @@ QgsRasterLayerProperties::QgsRasterLayerProperties( QgsMapLayer *lyr, QgsMapCanv
 
   QString title = QString( tr( "Layer Properties - %1" ) ).arg( lyr->name() );
   restoreOptionsBaseUi( title );
+  optionsStackedWidget_CurrentChanged( mOptionsStackedWidget->currentIndex() );
 } // QgsRasterLayerProperties ctor
 
 
@@ -1488,6 +1499,10 @@ void QgsRasterLayerProperties::optionsStackedWidget_CurrentChanged( int index )
 {
   QgsOptionsDialogBase::optionsStackedWidget_CurrentChanged( index );
 
+  bool isMetadataPanel = ( index == mOptStackedWidget->indexOf( mOptsPage_Metadata ) );
+  mBtnStyle->setVisible( ! isMetadataPanel );
+  mBtnMetadata->setVisible( isMetadataPanel );
+
   if ( !mHistogramWidget )
     return;
 
@@ -1856,6 +1871,102 @@ void QgsRasterLayerProperties::saveStyleAs_clicked()
     QMessageBox::information( this, tr( "Saved Style" ), message );
 }
 
+//
+//
+// Next four methods for saving and restoring QMD metadata
+//
+//
+
+void QgsRasterLayerProperties::loadMetadata()
+{
+  QgsSettings myQSettings;  // where we keep last used filter in persistent state
+  QString myLastUsedDir = myQSettings.value( QStringLiteral( "style/lastStyleDir" ), QDir::homePath() ).toString();
+
+  QString myFileName = QFileDialog::getOpenFileName( this, tr( "Load layer metadata from metadata file" ), myLastUsedDir,
+                       tr( "QGIS Layer Metadata File" ) + " (*.qmd)" );
+  if ( myFileName.isNull() )
+  {
+    return;
+  }
+
+  QString myMessage;
+  bool defaultLoadedFlag = false;
+  myMessage = mRasterLayer->loadNamedMetadata( myFileName, defaultLoadedFlag );
+
+  //reset if the default style was loaded OK only
+  if ( defaultLoadedFlag )
+  {
+    mMetadataWidget->setMetadata( mRasterLayer->metadata() );
+  }
+  else
+  {
+    //let the user know what went wrong
+    QMessageBox::warning( this, tr( "Load Metadata" ), myMessage );
+  }
+
+  QFileInfo myFI( myFileName );
+  QString myPath = myFI.path();
+  myQSettings.setValue( QStringLiteral( "style/lastStyleDir" ), myPath );
+
+  activateWindow(); // set focus back to properties dialog
+}
+
+void QgsRasterLayerProperties::saveMetadataAs()
+{
+  QgsSettings myQSettings;  // where we keep last used filter in persistent state
+  QString myLastUsedDir = myQSettings.value( QStringLiteral( "style/lastStyleDir" ), QDir::homePath() ).toString();
+
+  QString myOutputFileName = QFileDialog::getSaveFileName( this, tr( "Save layer metadata as QMD" ),
+                             myLastUsedDir, tr( "QMD File" ) + " (*.qmd)" );
+  if ( myOutputFileName.isNull() ) //dialog canceled
+  {
+    return;
+  }
+
+  mMetadataWidget->acceptMetadata();
+
+  //ensure the user never omitted the extension from the file name
+  if ( !myOutputFileName.endsWith( QgsMapLayer::extensionPropertyType( QgsMapLayer::Metadata ), Qt::CaseInsensitive ) )
+  {
+    myOutputFileName += QgsMapLayer::extensionPropertyType( QgsMapLayer::Metadata );
+  }
+
+  bool defaultLoadedFlag = false;
+  QString message = mRasterLayer->saveNamedMetadata( myOutputFileName, defaultLoadedFlag );
+  if ( defaultLoadedFlag )
+    myQSettings.setValue( QStringLiteral( "style/lastStyleDir" ), QFileInfo( myOutputFileName ).absolutePath() );
+  else
+    QMessageBox::information( this, tr( "Saved Metadata" ), message );
+}
+
+void QgsRasterLayerProperties::saveDefaultMetadata()
+{
+  mMetadataWidget->acceptMetadata();
+
+  bool defaultSavedFlag = false;
+  QString errorMsg = mRasterLayer->saveDefaultMetadata( defaultSavedFlag );
+  if ( !defaultSavedFlag )
+  {
+    QMessageBox::warning( this, tr( "Default Metadata" ), errorMsg );
+  }
+}
+
+void QgsRasterLayerProperties::loadDefaultMetadata()
+{
+  bool defaultLoadedFlag = false;
+  QString myMessage = mRasterLayer->loadNamedMetadata( mRasterLayer->metadataUri(), defaultLoadedFlag );
+  //reset if the default metadata was loaded OK only
+  if ( defaultLoadedFlag )
+  {
+    mMetadataWidget->setMetadata( mRasterLayer->metadata() );
+  }
+  else
+  {
+    QMessageBox::information( this, tr( "Default Metadata" ), myMessage );
+  }
+}
+
+
 void QgsRasterLayerProperties::toggleBuildPyramidsButton()
 {
   if ( lbxPyramidResolutions->selectedItems().empty() )

src/app/qgsrasterlayerproperties.h

@@ -103,6 +103,16 @@ class APP_EXPORT QgsRasterLayerProperties : public QgsOptionsDialogBase, private
     void loadStyle_clicked();
     //! Save a style when appriate button is pressed.
     void saveStyleAs_clicked();
+
+    //! Load a saved metadata file.
+    void loadMetadata();
+    //! Save a metadata.
+    void saveMetadataAs();
+    //! Save the default metadata.
+    void saveDefaultMetadata();
+    //! Load the default metadata.
+    void loadDefaultMetadata();
+
     //! Help button
     void showHelp();
 
@@ -131,6 +141,11 @@ class APP_EXPORT QgsRasterLayerProperties : public QgsOptionsDialogBase, private
     void refreshLegend( const QString &layerID, bool expandItem );
 
   private:
+    QPushButton *mBtnStyle = nullptr;
+    QPushButton *mBtnMetadata = nullptr;
+    QAction *mActionLoadMetadata = nullptr;
+    QAction *mActionSaveMetadataAs = nullptr;
+
     //! \brief  A constant that signals property not used
     const QString TRSTRING_NOT_SET;