port PostgreSQL execute and load SQL algorithm to C++

python/plugins/processing/algs/qgis/QgisAlgorithmProvider.py

@@ -42,7 +42,6 @@
 from .PointsDisplacement import PointsDisplacement
 from .PointsFromLines import PointsFromLines
 from .PolarPlot import PolarPlot
-from .PostGISExecuteAndLoadSQL import PostGISExecuteAndLoadSQL
 from .RandomExtractWithinSubsets import RandomExtractWithinSubsets
 from .RandomPointsAlongLines import RandomPointsAlongLines
 from .RandomPointsLayer import RandomPointsLayer
@@ -98,7 +97,6 @@ def getAlgs(self):
             PointsDisplacement(),
             PointsFromLines(),
             PolarPlot(),
-            PostGISExecuteAndLoadSQL(),
             RandomExtractWithinSubsets(),
             RandomPointsAlongLines(),
             RandomPointsLayer(),

src/analysis/CMakeLists.txt

@@ -122,6 +122,7 @@ set(QGIS_ANALYSIS_SRCS
   processing/qgsalgorithmdropgeometry.cpp
   processing/qgsalgorithmdropmzvalues.cpp
   processing/qgsalgorithmdxfexport.cpp
+  processing/qgsalgorithmexecuteandloadpostgisquery.cpp
   processing/qgsalgorithmexecutepostgisquery.cpp
   processing/qgsalgorithmexecutespatialitequery.cpp
   processing/qgsalgorithmexecutespatialitequeryregistered.cpp

src/analysis/processing/qgsalgorithmexecuteandloadpostgisquery.cpp

@@ -0,0 +1,125 @@
+/***************************************************************************
+                         qgsalgorithmexecuteandloadpostgisquery.cpp
+                         ---------------------
+    begin                : December 2025
+    copyright            : (C) 2025 by Alexander Bruy
+    email                : alexander dot bruy at gmail dot com
+ ***************************************************************************/
+
+/***************************************************************************
+ *                                                                         *
+ *   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 "qgsalgorithmexecuteandloadpostgisquery.h"
+
+#include "qgsabstractdatabaseproviderconnection.h"
+#include "qgsprovidermetadata.h"
+#include "qgsproviderregistry.h"
+#include "qgsvectorlayer.h"
+
+///@cond PRIVATE
+
+QString QgsExecuteAndLoadPostgisQueryAlgorithm::name() const
+{
+  return u"postgisexecuteandloadsql"_s;
+}
+
+QString QgsExecuteAndLoadPostgisQueryAlgorithm::displayName() const
+{
+  return QObject::tr( "PostgreSQL execute and load SQL" );
+}
+
+QStringList QgsExecuteAndLoadPostgisQueryAlgorithm::tags() const
+{
+  return QObject::tr( "database,sql,postgresql,postgis,execute,load,layer,table" ).split( ',' );
+}
+
+QString QgsExecuteAndLoadPostgisQueryAlgorithm::group() const
+{
+  return QObject::tr( "Database" );
+}
+
+QString QgsExecuteAndLoadPostgisQueryAlgorithm::groupId() const
+{
+  return u"database"_s;
+}
+
+QString QgsExecuteAndLoadPostgisQueryAlgorithm::shortHelpString() const
+{
+  return QObject::tr( "This algorithm performs a SQL database query on a PostgreSQL database connected to QGIS and loads the query results as a new layer." );
+}
+
+QString QgsExecuteAndLoadPostgisQueryAlgorithm::shortDescription() const
+{
+  return QObject::tr( "Executes a SQL command on a PostgreSQL database and loads the result as a layer." );
+}
+
+Qgis::ProcessingAlgorithmFlags QgsExecuteAndLoadPostgisQueryAlgorithm::flags() const
+{
+  return QgsProcessingAlgorithm::flags() | Qgis::ProcessingAlgorithmFlag::NotAvailableInStandaloneTool | Qgis::ProcessingAlgorithmFlag::RequiresProject;
+}
+
+QgsExecuteAndLoadPostgisQueryAlgorithm *QgsExecuteAndLoadPostgisQueryAlgorithm::createInstance() const
+{
+  return new QgsExecuteAndLoadPostgisQueryAlgorithm();
+}
+
+void QgsExecuteAndLoadPostgisQueryAlgorithm::initAlgorithm( const QVariantMap & )
+{
+  addParameter( new QgsProcessingParameterProviderConnection( u"DATABASE"_s, QObject::tr( "Database (connection name)" ), u"postgres"_s ) );
+  addParameter( new QgsProcessingParameterString( u"SQL"_s, QObject::tr( "SQL query" ), QVariant(), true ) );
+  addParameter( new QgsProcessingParameterString( u"ID_FIELD"_s, QObject::tr( "Unique ID field name" ), u"id"_s ) );
+  addParameter( new QgsProcessingParameterString( u"GEOMETRY_FIELD"_s, QObject::tr( "Geometry field name" ), u"geom"_s, false, true ) );
+  addOutput( new QgsProcessingOutputVectorLayer( u"OUTPUT"_s, QObject::tr( "Output layer" ) ) );
+}
+
+QVariantMap QgsExecuteAndLoadPostgisQueryAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
+{
+  Q_UNUSED( feedback );
+
+  const QString connName = parameterAsConnectionName( parameters, u"DATABASE"_s, context );
+
+  std::unique_ptr<QgsAbstractDatabaseProviderConnection> conn;
+  try
+  {
+    QgsProviderMetadata *md = QgsProviderRegistry::instance()->providerMetadata( u"postgres"_s );
+    conn.reset( static_cast<QgsAbstractDatabaseProviderConnection *>( md->createConnection( connName ) ) );
+  }
+  catch ( QgsProviderConnectionException & )
+  {
+    throw QgsProcessingException( QObject::tr( "Could not retrieve connection details for %1" ).arg( connName ) );
+  }
+
+  QString sql = parameterAsString( parameters, u"SQL"_s, context ).replace( '\n', ' ' );
+  if ( sql.endsWith( ';' ) )
+  {
+    sql.chop( 1 );
+  }
+  const QString idField = parameterAsString( parameters, u"ID_FIELD"_s, context );
+  const QString geomField = parameterAsString( parameters, u"GEOMETRY_FIELD"_s, context );
+
+  QgsDataSourceUri uri( conn->uri() );
+  uri.setDataSource( QString(), u"(%1)"_s.arg( sql ), geomField, QString(), idField );
+
+  auto layer = std::make_unique<QgsVectorLayer>( uri.uri(), u"layername"_s, u"postgres"_s );
+  if ( !layer->isValid() )
+  {
+    throw QgsProcessingException( QObject::tr( "This layer is invalid! Please check the PostGIS log for error messages." ) );
+  }
+
+  const QString layerId = layer->id();
+  const QgsProcessingContext::LayerDetails details( u"SQL layer"_s, context.project(), u"OUTPUT"_s, QgsProcessingUtils::LayerHint::Vector );
+  context.addLayerToLoadOnCompletion( layerId, details );
+  context.temporaryLayerStore()->addMapLayer( layer.release() );
+
+  QVariantMap outputs;
+  outputs.insert( u"OUTPUT"_s, layerId );
+  return outputs;
+}
+
+///@endcond

src/analysis/processing/qgsalgorithmexecuteandloadpostgisquery.h

@@ -0,0 +1,52 @@
+/***************************************************************************
+                         qgsalgorithmexecuteandloadpostgisquery.h
+                         ------------------------------
+    begin                : December 2025
+    copyright            : (C) 2025 by Alexander Bruy
+    email                : alexander dot bruy at gmail dot com
+ ***************************************************************************/
+
+/***************************************************************************
+ *                                                                         *
+ *   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.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef QGSALGORITHMEXECUTEANDLOADPOSTGISQUERY_H
+#define QGSALGORITHMEXECUTEANDLOADPOSTGISQUERY_H
+
+#define SIP_NO_FILE
+
+#include "qgsprocessingalgorithm.h"
+
+///@cond PRIVATE
+
+/**
+ * Native execute and load PostGIS query algorithm.
+ */
+class QgsExecuteAndLoadPostgisQueryAlgorithm : public QgsProcessingAlgorithm
+{
+  public:
+    QgsExecuteAndLoadPostgisQueryAlgorithm() = default;
+    void initAlgorithm( const QVariantMap &configuration = QVariantMap() ) override;
+    QString name() const override;
+    QString displayName() const override;
+    QStringList tags() const override;
+    QString group() const override;
+    QString groupId() const override;
+    QString shortHelpString() const override;
+    QString shortDescription() const override;
+    Qgis::ProcessingAlgorithmFlags flags() const override;
+    QgsExecuteAndLoadPostgisQueryAlgorithm *createInstance() const override SIP_FACTORY;
+
+  protected:
+    QVariantMap processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback ) override;
+};
+
+///@endcond PRIVATE
+
+
+#endif // QGSALGORITHMEXECUTEANDLOADPOSTGISQUERY_H

src/analysis/processing/qgsnativealgorithms.cpp

@@ -94,6 +94,7 @@
 #include "qgsalgorithmdropgeometry.h"
 #include "qgsalgorithmdropmzvalues.h"
 #include "qgsalgorithmdxfexport.h"
+#include "qgsalgorithmexecuteandloadpostgisquery.h"
 #include "qgsalgorithmexecutepostgisquery.h"
 #include "qgsalgorithmexecutespatialitequery.h"
 #include "qgsalgorithmexecutespatialitequeryregistered.h"
@@ -431,6 +432,7 @@ void QgsNativeAlgorithms::loadAlgorithms()
   addAlgorithm( new QgsDropGeometryAlgorithm() );
   addAlgorithm( new QgsDropMZValuesAlgorithm() );
   addAlgorithm( new QgsDxfExportAlgorithm() );
+  addAlgorithm( new QgsExecuteAndLoadPostgisQueryAlgorithm() );
   addAlgorithm( new QgsExecutePostgisQueryAlgorithm() );
   addAlgorithm( new QgsExecuteRegisteredSpatialiteQueryAlgorithm() );
   addAlgorithm( new QgsExecuteSpatialiteQueryAlgorithm() );