[processing] Add a model-only algorithm for renaming layers

This is required for algorithms with behaviour which depends on the layer names (e.g. the package algorithm uses the layer name as the table name in the geopackage). We need a way for models to be able to explicitly specify a layer name for this algorithm to be useful in models, otherwise the auto-generated temporary layer names are used (which are not very nice!)
qgis · Nov 26, 2017 · 6283ca6 · 6283ca6
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diff --git a/src/analysis/CMakeLists.txt b/src/analysis/CMakeLists.txt
@@ -50,6 +50,7 @@ SET(QGIS_ANALYSIS_SRCS
   processing/qgsalgorithmpromotetomultipart.cpp
   processing/qgsalgorithmrasterlayeruniquevalues.cpp
   processing/qgsalgorithmremovenullgeometry.cpp
+  processing/qgsalgorithmrenamelayer.cpp
   processing/qgsalgorithmsaveselectedfeatures.cpp
   processing/qgsalgorithmsimplify.cpp
   processing/qgsalgorithmsmooth.cpp

diff --git a/src/analysis/processing/qgsalgorithmrenamelayer.cpp b/src/analysis/processing/qgsalgorithmrenamelayer.cpp
@@ -0,0 +1,87 @@
+/***************************************************************************
+                         qgsalgorithmrenamelayer.cpp
+                         ---------------------
+    begin                : November 2017
+    copyright            : (C) 2017 by Nyall Dawson
+    email                : nyall dot dawson 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 "qgsalgorithmrenamelayer.h"
+
+///@cond PRIVATE
+
+QString QgsRenameLayerAlgorithm::name() const
+{
+  return QStringLiteral( "renamelayer" );
+}
+
+QgsProcessingAlgorithm::Flags QgsRenameLayerAlgorithm::flags() const
+{
+  return FlagHideFromToolbox;
+}
+
+QString QgsRenameLayerAlgorithm::displayName() const
+{
+  return QObject::tr( "Rename layer" );
+}
+
+QStringList QgsRenameLayerAlgorithm::tags() const
+{
+  return QObject::tr( "change,layer,name" ).split( ',' );
+}
+
+QString QgsRenameLayerAlgorithm::group() const
+{
+  return QObject::tr( "Modeler tool" );
+}
+
+QString QgsRenameLayerAlgorithm::shortHelpString() const
+{
+  return QObject::tr( "This algorithm renames a layer." );
+}
+
+QgsRenameLayerAlgorithm *QgsRenameLayerAlgorithm::createInstance() const
+{
+  return new QgsRenameLayerAlgorithm();
+}
+
+void QgsRenameLayerAlgorithm::initAlgorithm( const QVariantMap & )
+{
+  addParameter( new QgsProcessingParameterMapLayer( QStringLiteral( "INPUT" ), QObject::tr( "Layer" ) ) );
+  addParameter( new QgsProcessingParameterString( QStringLiteral( "NAME" ), QObject::tr( "New name" ) ) );
+  addOutput( new QgsProcessingOutputMapLayer( QStringLiteral( "OUTPUT" ), QObject::tr( "Layer" ) ) );
+}
+
+QVariantMap QgsRenameLayerAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
+{
+  QgsMapLayer *layer = parameterAsLayer( parameters, QStringLiteral( "INPUT" ), context );
+  QString name = parameterAsString( parameters, QStringLiteral( "NAME" ), context );
+
+  if ( !layer )
+    throw QgsProcessingException( QObject::tr( "Invalid input layer" ) );
+
+  if ( name.isEmpty() )
+    throw QgsProcessingException( QObject::tr( "Invalid (empty) layer name" ) );
+
+  bool parameterWasLayerName = parameters.value( QStringLiteral( "INPUT" ) ).toString() == layer->name();
+
+  layer->setName( name );
+  QVariantMap results;
+  if ( parameterWasLayerName )
+    results.insert( QStringLiteral( "OUTPUT" ), name );
+  else
+    results.insert( QStringLiteral( "OUTPUT" ), parameters.value( QStringLiteral( "INPUT" ) ) );
+
+  return results;
+}
+
+///@endcond
diff --git a/src/analysis/processing/qgsalgorithmrenamelayer.h b/src/analysis/processing/qgsalgorithmrenamelayer.h
@@ -0,0 +1,53 @@
+/***************************************************************************
+                         qgsalgorithmrenamelayer.h
+                         ---------------------
+    begin                : November 2017
+    copyright            : (C) 2017 by Nyall Dawson
+    email                : nyall dot dawson 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 QGSALGORITHMRENAMELAYER_H
+#define QGSALGORITHMRENAMELAYER_H
+
+#define SIP_NO_FILE
+
+#include "qgis.h"
+#include "qgsprocessingalgorithm.h"
+
+///@cond PRIVATE
+
+/**
+ * Native rename layer algorithm.
+ */
+class QgsRenameLayerAlgorithm : public QgsProcessingAlgorithm
+{
+  public:
+    QgsRenameLayerAlgorithm() = default;
+    void initAlgorithm( const QVariantMap &configuration = QVariantMap() ) override;
+    Flags flags() const override;
+    QString name() const override;
+    QString displayName() const override;
+    virtual QStringList tags() const override;
+    QString group() const override;
+    QString shortHelpString() const override;
+    QgsRenameLayerAlgorithm *createInstance() const override SIP_FACTORY;
+
+  protected:
+
+    virtual QVariantMap processAlgorithm( const QVariantMap &parameters,
+                                          QgsProcessingContext &context, QgsProcessingFeedback * ) override;
+
+};
+
+///@endcond PRIVATE
+
+#endif // QGSALGORITHMRENAMELAYER_H
diff --git a/src/analysis/processing/qgsnativealgorithms.cpp b/src/analysis/processing/qgsnativealgorithms.cpp
@@ -47,6 +47,7 @@
 #include "qgsalgorithmpromotetomultipart.h"
 #include "qgsalgorithmrasterlayeruniquevalues.h"
 #include "qgsalgorithmremovenullgeometry.h"
+#include "qgsalgorithmrenamelayer.h"
 #include "qgsalgorithmsaveselectedfeatures.h"
 #include "qgsalgorithmsimplify.h"
 #include "qgsalgorithmsmooth.h"
@@ -124,6 +125,7 @@ void QgsNativeAlgorithms::loadAlgorithms()
   addAlgorithm( new QgsPromoteToMultipartAlgorithm() );
   addAlgorithm( new QgsRasterLayerUniqueValuesReportAlgorithm() );
   addAlgorithm( new QgsRemoveNullGeometryAlgorithm() );
+  addAlgorithm( new QgsRenameLayerAlgorithm() );
   addAlgorithm( new QgsSaveSelectedFeatures() );
   addAlgorithm( new QgsSelectByLocationAlgorithm() );
   addAlgorithm( new QgsSimplifyAlgorithm() );

diff --git a/tests/src/analysis/testqgsprocessingalgs.cpp b/tests/src/analysis/testqgsprocessingalgs.cpp
@@ -34,6 +34,7 @@ class TestQgsProcessingAlgs: public QObject
     void init() {} // will be called before each testfunction is executed.
     void cleanup() {} // will be called after every testfunction.
     void packageAlg();
+    void renameLayerAlg();
 
   private:
 
@@ -116,6 +117,58 @@ void TestQgsProcessingAlgs::packageAlg()
   QCOMPARE( polygonLayer->featureCount(), mPolygonLayer->featureCount() );
 }
 
+void TestQgsProcessingAlgs::renameLayerAlg()
+{
+  const QgsProcessingAlgorithm *package( QgsApplication::processingRegistry()->algorithmById( QStringLiteral( "native:renamelayer" ) ) );
+  QVERIFY( package );
+
+  std::unique_ptr< QgsProcessingContext > context = qgis::make_unique< QgsProcessingContext >();
+  context->setProject( QgsProject::instance() );
+
+  QgsVectorLayer *layer = new QgsVectorLayer( QStringLiteral( "Point?field=col1:real" ), QStringLiteral( "layer" ), QStringLiteral( "memory" ) );
+  QVERIFY( layer->isValid() );
+  QgsProject::instance()->addMapLayer( layer );
+
+  QgsProcessingFeedback feedback;
+
+  QVariantMap parameters;
+
+  // bad layer
+  parameters.insert( QStringLiteral( "INPUT" ), QStringLiteral( "bad layer" ) );
+  parameters.insert( QStringLiteral( "NAME" ), QStringLiteral( "new name" ) );
+  bool ok = false;
+  ( void )package->run( parameters, *context, &feedback, &ok );
+  QVERIFY( !ok );
+  QCOMPARE( layer->name(), QStringLiteral( "layer" ) );
+
+  //invalid name
+  parameters.insert( QStringLiteral( "INPUT" ), QStringLiteral( "layer" ) );
+  parameters.insert( QStringLiteral( "NAME" ), QString() );
+  ok = false;
+  ( void )package->run( parameters, *context, &feedback, &ok );
+  QVERIFY( !ok );
+  QCOMPARE( layer->name(), QStringLiteral( "layer" ) );
+
+  //good params
+  parameters.insert( QStringLiteral( "INPUT" ), QVariant::fromValue( layer ) );
+  parameters.insert( QStringLiteral( "NAME" ), QStringLiteral( "new name" ) );
+  ok = false;
+  QVariantMap results = package->run( parameters, *context, &feedback, &ok );
+  QVERIFY( ok );
+  QCOMPARE( layer->name(), QStringLiteral( "new name" ) );
+  QCOMPARE( results.value( "OUTPUT" ), QVariant::fromValue( layer ) );
+
+  // with input layer name as parameter
+  parameters.insert( QStringLiteral( "INPUT" ), QStringLiteral( "new name" ) );
+  parameters.insert( QStringLiteral( "NAME" ), QStringLiteral( "new name2" ) );
+  ok = false;
+  results = package->run( parameters, *context, &feedback, &ok );
+  QVERIFY( ok );
+  QCOMPARE( layer->name(), QStringLiteral( "new name2" ) );
+  // result should use new name as value
+  QCOMPARE( results.value( "OUTPUT" ).toString(), QStringLiteral( "new name2" ) );
+}
+
 
 QGSTEST_MAIN( TestQgsProcessingAlgs )
 #include "testqgsprocessingalgs.moc"