[processing] Add method for providers to specify a different list

of supported output formats when an output has no geometry

python/core/auto_generated/processing/qgsprocessingprovider.sip.in

@@ -113,11 +113,31 @@ Returns a list of the raster format file extensions supported by this provider.
 %Docstring
 Returns a list of the vector format file extensions supported by this provider.
 
+.. seealso:: :py:func:`supportedOutputTableExtensions`
+
 .. seealso:: :py:func:`defaultVectorFileExtension`
 
 .. seealso:: :py:func:`supportedOutputRasterLayerExtensions`
 
 .. seealso:: :py:func:`supportsNonFileBasedOutput`
+%End
+
+    virtual QStringList supportedOutputTableExtensions() const;
+%Docstring
+Returns a list of the table (geometry-less vector layers) file extensions supported by this provider.
+
+By default this is the same as supportedOutputVectorLayerExtensions(). Providers which utilize different
+formats for geometry-less layers can override this method to return a different list of supported formats.
+
+.. seealso:: :py:func:`supportedOutputVectorLayerExtensions`
+
+.. seealso:: :py:func:`defaultVectorFileExtension`
+
+.. seealso:: :py:func:`supportedOutputRasterLayerExtensions`
+
+.. seealso:: :py:func:`supportsNonFileBasedOutput`
+
+.. versionadded:: 3.4.3
 %End
 
     virtual QString defaultVectorFileExtension( bool hasGeometry = true ) const;

src/core/processing/qgsprocessingparameters.cpp

@@ -3728,11 +3728,17 @@ QStringList QgsProcessingParameterFeatureSink::supportedOutputVectorLayerExtensi
 {
   if ( originalProvider() )
   {
-    return originalProvider()->supportedOutputVectorLayerExtensions();
+    if ( hasGeometry() )
+      return originalProvider()->supportedOutputVectorLayerExtensions();
+    else
+      return originalProvider()->supportedOutputTableExtensions();
   }
   else if ( QgsProcessingProvider *p = provider() )
   {
-    return p->supportedOutputVectorLayerExtensions();
+    if ( hasGeometry() )
+      return p->supportedOutputVectorLayerExtensions();
+    else
+      return p->supportedOutputTableExtensions();
   }
   else
   {
@@ -4288,11 +4294,17 @@ QStringList QgsProcessingParameterVectorDestination::supportedOutputVectorLayerE
 {
   if ( originalProvider() )
   {
-    return originalProvider()->supportedOutputVectorLayerExtensions();
+    if ( hasGeometry() )
+      return originalProvider()->supportedOutputVectorLayerExtensions();
+    else
+      return originalProvider()->supportedOutputTableExtensions();
   }
   else if ( QgsProcessingProvider *p = provider() )
   {
-    return p->supportedOutputVectorLayerExtensions();
+    if ( hasGeometry() )
+      return p->supportedOutputVectorLayerExtensions();
+    else
+      return p->supportedOutputTableExtensions();
   }
   else
   {

src/core/processing/qgsprocessingprovider.cpp

@@ -102,6 +102,11 @@ QStringList QgsProcessingProvider::supportedOutputVectorLayerExtensions() const
   return QgsVectorFileWriter::supportedFormatExtensions();
 }
 
+QStringList QgsProcessingProvider::supportedOutputTableExtensions() const
+{
+  return supportedOutputVectorLayerExtensions();
+}
+
 QString QgsProcessingProvider::defaultVectorFileExtension( bool hasGeometry ) const
 {
   QgsSettings settings;

src/core/processing/qgsprocessingprovider.h

@@ -118,12 +118,28 @@ class CORE_EXPORT QgsProcessingProvider : public QObject
 
     /**
      * Returns a list of the vector format file extensions supported by this provider.
+     * \see supportedOutputTableExtensions()
      * \see defaultVectorFileExtension()
      * \see supportedOutputRasterLayerExtensions()
      * \see supportsNonFileBasedOutput()
      */
     virtual QStringList supportedOutputVectorLayerExtensions() const;
 
+    /**
+     * Returns a list of the table (geometry-less vector layers) file extensions supported by this provider.
+     *
+     * By default this is the same as supportedOutputVectorLayerExtensions(). Providers which utilize different
+     * formats for geometry-less layers can override this method to return a different list of supported formats.
+     *
+     * \see supportedOutputVectorLayerExtensions()
+     * \see defaultVectorFileExtension()
+     * \see supportedOutputRasterLayerExtensions()
+     * \see supportsNonFileBasedOutput()
+     *
+     * \since QGIS 3.4.3
+     */
+    virtual QStringList supportedOutputTableExtensions() const;
+
     /**
      * Returns the default file extension to use for vector outputs created by the
      * provider.

tests/src/analysis/testqgsprocessing.cpp

@@ -385,27 +385,7 @@ class DummyProviderNoLoad : public DummyProvider
 
 };
 
-class DummyProvider3 : public QgsProcessingProvider
-{
-  public:
 
-    DummyProvider3()  = default;
-    QString id() const override { return QStringLiteral( "dummy3" ); }
-    QString name() const override { return QStringLiteral( "dummy3" ); }
-
-    QStringList supportedOutputVectorLayerExtensions() const override
-    {
-      return QStringList() << QStringLiteral( "mif" ) << QStringLiteral( "tab" );
-    }
-
-    QStringList supportedOutputRasterLayerExtensions() const override
-    {
-      return QStringList() << QStringLiteral( "mig" ) << QStringLiteral( "asc" );
-    }
-
-    void loadAlgorithms() override {}
-
-};
 
 class DummyAlgorithm2 : public QgsProcessingAlgorithm
 {
@@ -433,6 +413,36 @@ class DummyAlgorithm2 : public QgsProcessingAlgorithm
 };
 
 
+class DummyProvider3 : public QgsProcessingProvider
+{
+  public:
+
+    DummyProvider3()  = default;
+    QString id() const override { return QStringLiteral( "dummy3" ); }
+    QString name() const override { return QStringLiteral( "dummy3" ); }
+
+    QStringList supportedOutputVectorLayerExtensions() const override
+    {
+      return QStringList() << QStringLiteral( "mif" ) << QStringLiteral( "tab" );
+    }
+
+    QStringList supportedOutputTableExtensions() const override
+    {
+      return QStringList() << QStringLiteral( "dbf" );
+    }
+
+    QStringList supportedOutputRasterLayerExtensions() const override
+    {
+      return QStringList() << QStringLiteral( "mig" ) << QStringLiteral( "asc" );
+    }
+
+    void loadAlgorithms() override
+    {
+      QVERIFY( addAlgorithm( new DummyAlgorithm2( "alg1" ) ) );
+    }
+
+};
+
 class DummyProvider4 : public QgsProcessingProvider
 {
   public:
@@ -564,6 +574,7 @@ class TestQgsProcessing: public QObject
     void indicesToFields();
     void stringToPythonLiteral();
     void defaultExtensionsForProvider();
+    void supportedExtensions();
     void supportsNonFileBasedOutput();
     void addParameterType();
     void removeParameterType();
@@ -4678,6 +4689,30 @@ void TestQgsProcessing::parameterFeatureSink()
   QCOMPARE( QgsProcessingAlgorithm::invalidSinkError( params, QStringLiteral( "OUTPUT" ) ), QStringLiteral( "Could not create destination layer for OUTPUT: d:/test3.shp" ) );
   params.insert( QStringLiteral( "OUTPUT" ), QgsProcessingFeatureSourceDefinition( QStringLiteral( "source" ) ) );
   QCOMPARE( QgsProcessingAlgorithm::invalidSinkError( params, QStringLiteral( "OUTPUT" ) ), QStringLiteral( "Could not create destination layer for OUTPUT: invalid value" ) );
+
+  // test supported output vector layer extensions
+
+  def.reset( new QgsProcessingParameterFeatureSink( "with_geom", QString(), QgsProcessing::TypeVectorAnyGeometry, QString(), true ) );
+  DummyProvider3 provider;
+  provider.loadAlgorithms();
+  def->mOriginalProvider = &provider;
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().count(), 2 );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().at( 0 ), QStringLiteral( "mif" ) );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().at( 1 ), QStringLiteral( "tab" ) );
+  def->mOriginalProvider = nullptr;
+  def->mAlgorithm = const_cast< QgsProcessingAlgorithm * >( provider.algorithms().at( 0 ) );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().count(), 2 );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().at( 0 ), QStringLiteral( "mif" ) );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().at( 1 ), QStringLiteral( "tab" ) );
+
+  def.reset( new QgsProcessingParameterFeatureSink( "no_geom", QString(), QgsProcessing::TypeVector, QString(), true ) );
+  def->mOriginalProvider = &provider;
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().count(), 1 );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().at( 0 ), QStringLiteral( "dbf" ) );
+  def->mOriginalProvider = nullptr;
+  def->mAlgorithm = const_cast< QgsProcessingAlgorithm * >( provider.algorithms().at( 0 ) );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().count(), 1 );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().at( 0 ), QStringLiteral( "dbf" ) );
 }
 
 void TestQgsProcessing::parameterVectorOut()
@@ -4811,6 +4846,30 @@ void TestQgsProcessing::parameterVectorOut()
   QCOMPARE( context2.layersToLoadOnCompletion().values().at( 0 ).name, QStringLiteral( "my_dest" ) );
   QCOMPARE( context2.layersToLoadOnCompletion().values().at( 0 ).outputName, QStringLiteral( "x" ) );
   QCOMPARE( context2.layersToLoadOnCompletion().values().at( 0 ).layerTypeHint, QgsProcessingUtils::Vector );
+
+  // test supported output vector layer extensions
+
+  def.reset( new QgsProcessingParameterVectorDestination( "with_geom", QString(), QgsProcessing::TypeVectorAnyGeometry, QString(), true ) );
+  DummyProvider3 provider;
+  provider.loadAlgorithms();
+  def->mOriginalProvider = &provider;
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().count(), 2 );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().at( 0 ), QStringLiteral( "mif" ) );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().at( 1 ), QStringLiteral( "tab" ) );
+  def->mOriginalProvider = nullptr;
+  def->mAlgorithm = const_cast< QgsProcessingAlgorithm * >( provider.algorithms().at( 0 ) );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().count(), 2 );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().at( 0 ), QStringLiteral( "mif" ) );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().at( 1 ), QStringLiteral( "tab" ) );
+
+  def.reset( new QgsProcessingParameterVectorDestination( "no_geom", QString(), QgsProcessing::TypeVector, QString(), true ) );
+  def->mOriginalProvider = &provider;
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().count(), 1 );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().at( 0 ), QStringLiteral( "dbf" ) );
+  def->mOriginalProvider = nullptr;
+  def->mAlgorithm = const_cast< QgsProcessingAlgorithm * >( provider.algorithms().at( 0 ) );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().count(), 1 );
+  QCOMPARE( def->supportedOutputVectorLayerExtensions().at( 0 ), QStringLiteral( "dbf" ) );
 }
 
 void TestQgsProcessing::parameterRasterOut()
@@ -6971,6 +7030,17 @@ void TestQgsProcessing::defaultExtensionsForProvider()
   QCOMPARE( provider.defaultRasterFileExtension(), QStringLiteral( "mig" ) );
 }
 
+void TestQgsProcessing::supportedExtensions()
+{
+  DummyProvider4 provider;
+  QCOMPARE( provider.supportedOutputVectorLayerExtensions().count(), 1 );
+  QCOMPARE( provider.supportedOutputVectorLayerExtensions().at( 0 ), QStringLiteral( "mif" ) );
+
+  // if supportedOutputTableExtensions is not implemented, supportedOutputVectorLayerExtensions should be used instead
+  QCOMPARE( provider.supportedOutputTableExtensions().count(), 1 );
+  QCOMPARE( provider.supportedOutputTableExtensions().at( 0 ), QStringLiteral( "mif" ) );
+}
+
 void TestQgsProcessing::supportsNonFileBasedOutput()
 {
   DummyAlgorithm alg( QStringLiteral( "test" ) );