[processing] Allow modification of feature request when using

vector.features

Allows for optimising the request through subsets of attributes
or no geometry fetching

(cherry-picked from 9e1ddcb)

python/plugins/processing/tests/CMakeLists.txt

@@ -7,6 +7,7 @@ PLUGIN_INSTALL(processing tests/data ${TEST_DATA_FILES})
 IF(ENABLE_TESTS)
   INCLUDE(UsePythonTest)
   ADD_PYTHON_TEST(ProcessingParametersTest ParametersTest.py)
+  ADD_PYTHON_TEST(ProcessingToolsTest ToolsTest.py)
   ADD_PYTHON_TEST(ProcessingQgisAlgorithmsTest QgisAlgorithmsTest.py)
   ADD_PYTHON_TEST(ProcessingGdalAlgorithmsTest GdalAlgorithmsTest.py)
   ADD_PYTHON_TEST(ProcessingGrass7AlgorithmsImageryTest Grass7AlgorithmsImageryTest.py)

python/plugins/processing/tests/ToolsTest.py

@@ -0,0 +1,89 @@
+# -*- coding: utf-8 -*-
+
+"""
+***************************************************************************
+    ToolsTest
+    ---------------------
+    Date                 : July 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.                                   *
+*                                                                         *
+***************************************************************************
+"""
+
+__author__ = 'Nyall Dawson'
+__date__ = 'July 2016'
+__copyright__ = '(C) 2016, Nyall Dawson'
+
+# This will get replaced with a git SHA1 when you do a git archive
+
+__revision__ = '$Format:%H$'
+
+from qgis.testing import start_app, unittest
+from processing.tests.TestData import points2
+from processing.tools import vector
+from qgis.core import (QgsVectorLayer, QgsFeatureRequest)
+from processing.core.ProcessingConfig import ProcessingConfig
+
+start_app()
+
+
+class VectorTest(unittest.TestCase):
+
+    def testFeatures(self):
+        ProcessingConfig.initialize()
+
+        test_data = points2()
+        test_layer = QgsVectorLayer(test_data, 'test', 'ogr')
+
+        # test with all features
+        features = vector.features(test_layer)
+        self.assertEqual(len(features), 8)
+        self.assertEqual(set([f.id() for f in features]), set([0, 1, 2, 3, 4, 5, 6, 7]))
+
+        # test with selected features
+        previous_value = ProcessingConfig.getSetting(ProcessingConfig.USE_SELECTED)
+        ProcessingConfig.setSettingValue(ProcessingConfig.USE_SELECTED, True)
+        test_layer.selectByIds([2, 4, 6])
+        features = vector.features(test_layer)
+        self.assertEqual(len(features), 3)
+        self.assertEqual(set([f.id() for f in features]), set([2, 4, 6]))
+
+        # selection, but not using selected features
+        ProcessingConfig.setSettingValue(ProcessingConfig.USE_SELECTED, False)
+        test_layer.selectByIds([2, 4, 6])
+        features = vector.features(test_layer)
+        self.assertEqual(len(features), 8)
+        self.assertEqual(set([f.id() for f in features]), set([0, 1, 2, 3, 4, 5, 6, 7]))
+
+        # using selected features, but no selection
+        ProcessingConfig.setSettingValue(ProcessingConfig.USE_SELECTED, True)
+        test_layer.removeSelection()
+        features = vector.features(test_layer)
+        self.assertEqual(len(features), 8)
+        self.assertEqual(set([f.id() for f in features]), set([0, 1, 2, 3, 4, 5, 6, 7]))
+
+        # test that feature request is honored
+        ProcessingConfig.setSettingValue(ProcessingConfig.USE_SELECTED, False)
+        features = vector.features(test_layer, QgsFeatureRequest().setFilterFids([1, 3, 5]))
+        self.assertEqual(set([f.id() for f in features]), set([1, 3, 5]))
+
+        # test that feature request is honored when using selections
+        ProcessingConfig.setSettingValue(ProcessingConfig.USE_SELECTED, True)
+        test_layer.selectByIds([2, 4, 6])
+        features = vector.features(test_layer, QgsFeatureRequest().setFlags(QgsFeatureRequest.NoGeometry))
+        self.assertTrue(all([f.geometry() == None for f in features]))
+        features = vector.features(test_layer, QgsFeatureRequest().setFlags(QgsFeatureRequest.NoGeometry))
+        self.assertEqual(set([f.id() for f in features]), set([2, 4, 6]))
+
+        ProcessingConfig.setSettingValue(ProcessingConfig.USE_SELECTED, previous_value)
+
+
+if __name__ == '__main__':
+    unittest.main()

python/plugins/processing/tools/vector.py

@@ -37,7 +37,8 @@
 from qgis.PyQt.QtCore import QVariant, QSettings
 from qgis.core import (QGis, QgsFields, QgsField, QgsGeometry, QgsRectangle,
                        QgsSpatialIndex, QgsMapLayerRegistry, QgsMapLayer, QgsVectorLayer,
-                       QgsVectorFileWriter, QgsDistanceArea, QgsDataSourceURI, QgsCredentials)
+                       QgsVectorFileWriter, QgsDistanceArea, QgsDataSourceURI, QgsCredentials,
+                       QgsFeatureRequest)
 
 from processing.core.ProcessingConfig import ProcessingConfig
 from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
@@ -86,7 +87,7 @@
 }
 
 
-def features(layer):
+def features(layer, request=QgsFeatureRequest()):
     """This returns an iterator over features in a vector layer,
     considering the selection that might exist in the layer, and the
     configuration that indicates whether to use only selected feature
@@ -97,15 +98,15 @@ def features(layer):
     """
     class Features:
 
-        def __init__(self, layer):
+        def __init__(self, layer, request):
             self.layer = layer
             self.selection = False
-            self.iter = layer.getFeatures()
-            if ProcessingConfig.getSetting(ProcessingConfig.USE_SELECTED):
-                selected = layer.selectedFeatures()
-                if len(selected) > 0:
-                    self.selection = True
-                    self.iter = iter(selected)
+            if ProcessingConfig.getSetting(ProcessingConfig.USE_SELECTED)\
+                    and layer.selectedFeatureCount() > 0:
+                self.iter = layer.selectedFeaturesIterator(request)
+                self.selection = True
+            else:
+                self.iter = layer.getFeatures(request)
 
         def __iter__(self):
             return self.iter
@@ -116,7 +117,7 @@ def __len__(self):
             else:
                 return int(self.layer.featureCount())
 
-    return Features(layer)
+    return Features(layer, request)
 
 
 def uniqueValues(layer, attribute):