Add transaction groups

python/core/core.sip

@@ -19,6 +19,7 @@
 %Include qgis.sip
 
 %Include qgstransaction.sip
+%Include qgstransactiongroup.sip
 %Include qgsapplication.sip
 %Include qgsattributeaction.sip
 %Include qgsbrowsermodel.sip

python/core/qgstransaction.sip

@@ -59,6 +59,11 @@ class QgsTransaction : QObject /Abstract/
     /** Executes sql */
     virtual bool executeSql( const QString& sql, QString& error /Out/ ) = 0;
 
+    /**
+     * Checks if a the provider of a give layer supports transactions.
+     */
+    static bool supportsTransaction( const QgsVectorLayer* layer );
+
   signals:
     /**
      * Emitted after a rollback

python/core/qgstransactiongroup.sip

@@ -0,0 +1,56 @@
+/***************************************************************************
+  qgstransactiongroup.h - QgsTransactionGroup
+
+ ---------------------
+ begin                : 15.1.2016
+ copyright            : (C) 2016 by Matthias Kuhn
+ email                : mmatthias@opengis.ch
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+class QgsTransactionGroup : QObject
+{
+%TypeHeaderCode
+#include "qgstransactiongroup.h"
+%End
+  public:
+    explicit QgsTransactionGroup( QObject *parent = 0 );
+
+    ~QgsTransactionGroup();
+
+    /**
+     * Add a layer to this transaction group.
+     *
+     * Will return true if it is compatible and has been added.
+     */
+    bool addLayer( QgsVectorLayer* layer );
+
+    /**
+     * Return the connection string used by this transaction group.
+     * Layers need be compatible when added.
+     */
+    QString connString() const;
+
+    /**
+     * Return the provider key used by this transaction group.
+     * Layers need be compatible when added.
+     */
+    QString providerKey() const;
+
+    /**
+     * Returns true if there are no layers in this transaction group.
+     */
+    bool isEmpty() const;
+
+  signals:
+    /**
+     * Will be emitted whenever there is a commit error
+     */
+    void commitError( const QString& msg );
+};

python/core/qgsvectorlayer.sip

@@ -1015,14 +1015,6 @@ class QgsVectorLayer : QgsMapLayer
      */
     bool setReadOnly( bool readonly = true );
 
-    /**
-     * Make layer editable.
-     * This starts an edit session on this layer. Changes made in this edit session will not
-     * be made persistent until {@link commitChanges()} is called and can be reverted by calling
-     * {@link rollBack()}.
-     */
-    bool startEditing();
-
     /** Change feature's geometry */
     bool changeGeometry( QgsFeatureId fid, QgsGeometry* geom );
 
@@ -1493,6 +1485,15 @@ class QgsVectorLayer : QgsMapLayer
     /** Check if there is a join with a layer that will be removed */
     void checkJoinLayerRemove( const QString& theLayerId );
 
+    /**
+     * Make layer editable.
+     * This starts an edit session on this layer. Changes made in this edit session will not
+     * be made persistent until {@link commitChanges()} is called and can be reverted by calling
+     * {@link rollBack()}.
+     */
+    bool startEditing();
+
+
   protected slots:
     void invalidateSymbolCountedFlag();
 
@@ -1516,6 +1517,9 @@ class QgsVectorLayer : QgsMapLayer
     /** Is emitted, when layer is checked for modifications. Use for last-minute additions */
     void beforeModifiedCheck() const;
 
+    /** Is emitted, before editing on this layer is started */
+    void beforeEditingStarted();
+
     /** Is emitted, when editing on this layer has started*/
     void editingStarted();
 
@@ -1663,10 +1667,6 @@ class QgsVectorLayer : QgsMapLayer
      */
     void writeCustomSymbology( QDomElement& element, QDomDocument& doc, QString& errorMessage ) const;
 
-  private slots:
-    void onRelationsLoaded();
-    void onJoinedFieldsChanged();
-    void onFeatureDeleted( QgsFeatureId fid );
 
   protected:
     /** Set the extent */

src/core/CMakeLists.txt

@@ -190,6 +190,7 @@ SET(QGIS_CORE_SRCS
   qgstolerance.cpp
   qgstracer.cpp
   qgstransaction.cpp
+  qgstransactiongroup.cpp
   qgsvectordataprovider.cpp
   qgsvectorfilewriter.cpp
   qgsvectorlayer.cpp
@@ -459,6 +460,7 @@ SET(QGIS_CORE_MOC_HDRS
   qgssnappingutils.h
   qgstracer.h
   qgstransaction.h
+  qgstransactiongroup.h
   qgsvectordataprovider.h
   qgsvectorlayercache.h
   qgsvectorlayereditbuffer.h

src/core/qgstransaction.cpp

@@ -163,6 +163,15 @@ bool QgsTransaction::rollback( QString& errorMsg )
   return true;
 }
 
+bool QgsTransaction::supportsTransaction( const QgsVectorLayer* layer )
+{
+  QLibrary* lib = QgsProviderRegistry::instance()->providerLibrary( layer->providerType() );
+  if ( !lib )
+    return false;
+
+  return lib->resolve( "createTransaction" );
+}
+
 void QgsTransaction::onLayersDeleted( const QStringList& layerids )
 {
   Q_FOREACH ( const QString& layerid, layerids )

src/core/qgstransaction.h

@@ -85,6 +85,11 @@ class CORE_EXPORT QgsTransaction : public QObject
     /** Executes sql */
     virtual bool executeSql( const QString& sql, QString& error ) = 0;
 
+    /**
+     * Checks if a the provider of a give layer supports transactions.
+     */
+    static bool supportsTransaction( const QgsVectorLayer* layer );
+
   signals:
     /**
      * Emitted after a rollback

src/core/qgstransactiongroup.cpp

@@ -0,0 +1,154 @@
+/***************************************************************************
+  qgstransactiongroup.cpp - QgsTransactionGroup
+
+ ---------------------
+ begin                : 15.1.2016
+ copyright            : (C) 2016 by mku
+ email                : [your-email-here]
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+#include "qgstransactiongroup.h"
+
+#include "qgstransaction.h"
+#include "qgsvectorlayer.h"
+#include "qgsdatasourceuri.h"
+#include "qgsvectordataprovider.h"
+
+#include <QTimer>
+
+QgsTransactionGroup::QgsTransactionGroup( QObject *parent )
+    : QObject( parent )
+    , mEditingStarting( false )
+    , mEditingStopping( false )
+    , mTransaction( nullptr )
+{
+
+}
+
+QgsTransactionGroup::~QgsTransactionGroup()
+{
+  delete mTransaction;
+}
+
+bool QgsTransactionGroup::addLayer( QgsVectorLayer* layer )
+{
+  if ( !QgsTransaction::supportsTransaction( layer ) )
+    return false;
+
+  QString connString = QgsDataSourceURI( layer->source() ).connectionInfo();
+
+  if ( mConnString.isEmpty() )
+  {
+    mConnString = connString;
+    mProviderKey = layer->providerType();
+  }
+  else if ( mConnString != connString || mProviderKey != layer->providerType() )
+  {
+    return false;
+  }
+
+  mLayers.insert( layer );
+
+  connect( layer, SIGNAL( beforeEditingStarted() ), this, SLOT( onEditingStarted() ) );
+  connect( layer, SIGNAL( layerDeleted() ), this, SLOT( onLayerDeleted() ) );
+
+  return true;
+}
+
+void QgsTransactionGroup::onEditingStarted()
+{
+  if ( mTransaction )
+    return;
+
+  mTransaction = QgsTransaction::create( mConnString, mProviderKey );
+
+  QString errorMsg;
+  mTransaction->begin( errorMsg );
+
+  Q_FOREACH ( QgsVectorLayer* layer, mLayers )
+  {
+    mTransaction->addLayer( layer );
+    layer->startEditing();
+    connect( layer, SIGNAL( beforeCommitChanges() ), this, SLOT( onCommitChanges() ) );
+    connect( layer, SIGNAL( beforeRollBack() ), this, SLOT( onRollback() ) );
+  }
+}
+
+void QgsTransactionGroup::onLayerDeleted()
+{
+  mLayers.remove( qobject_cast<QgsVectorLayer*>( sender() ) );
+}
+
+void QgsTransactionGroup::onCommitChanges()
+{
+  if ( mEditingStopping )
+    return;
+
+  mEditingStopping = true;
+
+  QgsVectorLayer* triggeringLayer = qobject_cast<QgsVectorLayer*>( sender() );
+
+  QString errMsg;
+  if ( mTransaction->commit( errMsg ) )
+  {
+    Q_FOREACH ( QgsVectorLayer* layer, mLayers )
+    {
+      if ( layer != sender() )
+        layer->commitChanges();
+    }
+  }
+  else
+  {
+    emit commitError( errMsg );
+    // Restart editing the calling layer in the next event loop cycle
+    QTimer::singleShot( 0, triggeringLayer, SLOT( startEditing() ) );
+  }
+  mEditingStopping = false;
+}
+
+void QgsTransactionGroup::onRollback()
+{
+  if ( mEditingStopping )
+    return;
+
+  mEditingStopping = true;
+
+  QgsVectorLayer* triggeringLayer = qobject_cast<QgsVectorLayer*>( sender() );
+
+  QString errMsg;
+  if ( mTransaction->rollback( errMsg ) )
+  {
+    Q_FOREACH ( QgsVectorLayer* layer, mLayers )
+    {
+      if ( layer != triggeringLayer )
+        layer->rollBack();
+    }
+  }
+  else
+  {
+    // Restart editing the calling layer in the next event loop cycle
+    QTimer::singleShot( 0, triggeringLayer, SLOT( startEditing() ) );
+  }
+  mEditingStopping = false;
+}
+
+QString QgsTransactionGroup::providerKey() const
+{
+  return mProviderKey;
+}
+
+bool QgsTransactionGroup::isEmpty() const
+{
+  return mLayers.isEmpty();
+}
+
+QString QgsTransactionGroup::connString() const
+{
+  return mConnString;
+}