Fix processing algs crash when no source features exist

Instead we output an empty layer - this may be critical for
multi-step models where there is validly no features present
in a source layer

Author: nyalldawson

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

@@ -100,7 +100,7 @@ def processAlgorithm(self, parameters, context, feedback):
                                                fields, source.wkbType(), source.sourceCrs())
 
         features = source.getFeatures()
-        total = 100.0 / source.featureCount()
+        total = 100.0 / source.featureCount() if source.featureCount() else 0
 
         for current, input_feature in enumerate(features):
             if feedback.isCanceled():

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

@@ -74,7 +74,7 @@ def processAlgorithm(self, parameters, context, feedback):
                                                fields, source.wkbType(), source.sourceCrs())
 
         features = source.getFeatures()
-        total = 100.0 / source.featureCount()
+        total = total = 100.0 / source.featureCount() if source.featureCount() else 0
         for current, input_feature in enumerate(features):
             if feedback.isCanceled():
                 break

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

@@ -156,7 +156,7 @@ def processAlgorithm(self, parameters, context, feedback):
         return results
 
     def calcNumericStats(self, features, feedback, field, count):
-        total = 100.0 / float(count)
+        total = 100.0 / count if count else 0
         stat = QgsStatisticalSummary()
         for current, ft in enumerate(features):
             if feedback.isCanceled():
@@ -205,7 +205,7 @@ def calcNumericStats(self, features, feedback, field, count):
         return data, results
 
     def calcStringStats(self, features, feedback, field, count):
-        total = 100.0 / float(count)
+        total = 100.0 / count if count else 1
         stat = QgsStringStatisticalSummary()
         for current, ft in enumerate(features):
             if feedback.isCanceled():
@@ -237,7 +237,7 @@ def calcStringStats(self, features, feedback, field, count):
         return data, results
 
     def calcDateTimeStats(self, features, feedback, field, count):
-        total = 100.0 / float(count)
+        total = 100.0 / count if count else 1
         stat = QgsDateTimeStatisticalSummary()
         for current, ft in enumerate(features):
             if feedback.isCanceled():

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

@@ -86,7 +86,7 @@ def processAlgorithm(self, parameters, context, feedback):
                                                source.fields(), output_wkb, source.sourceCrs())
 
         features = source.getFeatures()
-        total = 100.0 / source.featureCount()
+        total = 100.0 / source.featureCount() if source.featureCount() else 0
 
         for current, input_feature in enumerate(features):
             if feedback.isCanceled():

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

@@ -78,7 +78,7 @@ def processAlgorithm(self, parameters, context, feedback):
                                                source.fields(), QgsWkbTypes.Polygon, source.sourceCrs())
 
         features = source.getFeatures()
-        total = 100.0 / source.featureCount()
+        total = 100.0 / source.featureCount() if source.featureCount() else 0
 
         for current, input_feature in enumerate(features):
             if feedback.isCanceled():

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

@@ -38,7 +38,7 @@ def buffering(feedback, context, writer, distance, field, useField, layer, disso
 
     current = 0
     features = QgsProcessingUtils.getFeatures(layer, context)
-    total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+    total = 100.0 / layer.featureCount() if layer.featureCount() else 0
 
     # With dissolve
     if dissolve:

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

@@ -129,7 +129,7 @@ def doCheck(self, method, parameters, context, feedback):
         error_count = 0
 
         features = source.getFeatures()
-        total = 100.0 / source.featureCount()
+        total = 100.0 / source.featureCount() if source.featureCount() else 0
         for current, inFeat in enumerate(features):
             if feedback.isCanceled():
                 break

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

@@ -120,7 +120,7 @@ def processAlgorithm(self, parameters, context, feedback):
         if useField:
             unique = layer.uniqueValues(index)
             current = 0
-            total = 100.0 / (QgsProcessingUtils.featureCount(layer, context) * len(unique))
+            total = 100.0 / (layer.featureCount() * len(unique)) if layer.featureCount() else 1
             for i in unique:
                 first = True
                 hull = []
@@ -152,7 +152,7 @@ def processAlgorithm(self, parameters, context, feedback):
                 fid += 1
         else:
             hull = []
-            total = 100.0 / layer.featureCount()
+            total = 100.0 / layer.featureCount() if layer.featureCount() else 1
             features = QgsProcessingUtils.getFeatures(layer, context)
             for current, f in enumerate(features):
                 inGeom = f.geometry()

python/plugins/processing/algs/qgis/Datasources2Vrt.py

@@ -110,7 +110,7 @@ def mergeDataSources2Vrt(self, dataSources, outFile, union=False, relative=False
         if union:
             vrt += '<OGRVRTUnionLayer name="UnionedLayer">'
 
-        total = 100.0 / len(dataSources)
+        total = 100.0 / len(dataSources) if dataSources else 1
         for current, inFile in enumerate(dataSources):
             feedback.setProgress(int(current * total))
 

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

@@ -92,7 +92,7 @@ def processAlgorithm(self, parameters, context, feedback):
         ptNdx = -1
         c = voronoi.Context()
         features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
         for current, inFeat in enumerate(features):
             geom = QgsGeometry(inFeat.geometry())
             if geom.isNull():
@@ -122,7 +122,7 @@ def processAlgorithm(self, parameters, context, feedback):
         triangles = c.triangles
         feat = QgsFeature()
 
-        total = 100.0 / len(triangles)
+        total = 100.0 / len(triangles) if triangles else 1
         for current, triangle in enumerate(triangles):
             indices = list(triangle)
             indices.append(indices[0])

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

@@ -91,7 +91,7 @@ def processAlgorithm(self, parameters, context, feedback):
                                                fields, source.wkbType(), source.sourceCrs())
 
         features = source.getFeatures()
-        total = 100.0 / source.featureCount()
+        total = 100.0 / source.featureCount() if source.featureCount() else 0
 
         for current, f in enumerate(features):
             if feedback.isCanceled():

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

@@ -68,7 +68,7 @@ def processAlgorithm(self, parameters, context, feedback):
 
         features = QgsProcessingUtils.getFeatures(layer, context)
 
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
         geoms = dict()
         for current, f in enumerate(features):
             geoms[f.id()] = f.geometry()
@@ -83,7 +83,7 @@ def processAlgorithm(self, parameters, context, feedback):
                 if g.isGeosEqual(cleaned[j]):
                     del cleaned[j]
 
-        total = 100.0 / len(cleaned)
+        total = 100.0 / len(cleaned) if cleaned else 1
         request = QgsFeatureRequest().setFilterFids(list(cleaned.keys()))
         for current, f in enumerate(layer.getFeatures(request)):
             writer.addFeature(f)

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

@@ -79,7 +79,7 @@ def processAlgorithm(self, parameters, context, feedback):
                                                source.fields(), source.wkbType(), source.sourceCrs())
 
         features = source.getFeatures()
-        total = 100.0 / source.featureCount()
+        total = 100.0 / source.featureCount() if source.featureCount() else 0
 
         for current, f in enumerate(features):
             if feedback.isCanceled():

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

@@ -82,7 +82,7 @@ def processAlgorithm(self, parameters, context, feedback):
                                                source.fields(), source.wkbType(), source.sourceCrs())
 
         features = source.getFeatures()
-        total = 100.0 / source.featureCount()
+        total = 100.0 / source.featureCount() if source.featureCount() else 0
 
         for current, f in enumerate(features):
             if feedback.isCanceled():

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

@@ -80,7 +80,7 @@ def processAlgorithm(self, parameters, context, feedback):
                                                source.fields(), source.wkbType(), source.sourceCrs())
 
         features = source.getFeatures()
-        total = 100.0 / source.featureCount()
+        total = 100.0 / source.featureCount() if source.featureCount() else 0
         for current, f in enumerate(features):
             if feedback.isCanceled():
                 break

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

@@ -80,7 +80,7 @@ def processAlgorithm(self, parameters, context, feedback):
         outFeat = QgsFeature()
         index = QgsProcessingUtils.createSpatialIndex(layerB, context)
         selectionA = QgsProcessingUtils.getFeatures(layerA, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layerA, context)
+        total = 100.0 / layerA.featureCount() if layerA.featureCount() else 0
         for current, inFeatA in enumerate(selectionA):
             geom = inFeatA.geometry()
             diff_geom = QgsGeometry(geom)

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

@@ -73,7 +73,7 @@ def processAlgorithm(self, parameters, context, feedback):
 
         request = QgsFeatureRequest().setFlags(QgsFeatureRequest.NoGeometry)
         features = source.getFeatures(request)
-        total = 100.0 / source.featureCount()
+        total = 100.0 / source.featureCount() if source.featureCount() else 0
 
         for current, input_feature in enumerate(features):
             if feedback.isCanceled():

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

@@ -77,7 +77,7 @@ def processAlgorithm(self, parameters, context, feedback):
         classes = {}
 
         features = QgsProcessingUtils.getFeatures(vlayer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(vlayer, context)
+        total = 100.0 / vlayer.featureCount() if vlayer.featureCount() else 0
         for current, feature in enumerate(features):
             feedback.setProgress(int(current * total))
             inGeom = feature.geometry()

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

@@ -151,7 +151,7 @@ def processAlgorithm(self, parameters, context, feedback):
                                                                            vLayer.crs(), context)
 
         features = QgsProcessingUtils.getFeatures(vLayer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(vLayer, context)
+        total = 100.0 / vLayer.featureCount() if vLayer.featureCount() else 0
         outFeat = QgsFeature()
         for current, inFeat in enumerate(features):
             outFeat.setAttributes(inFeat.attributes())

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

@@ -71,7 +71,7 @@ def processAlgorithm(self, parameters, context, feedback):
         writer = output.getVectorWriter(fields, QgsWkbTypes.LineString, vlayer.crs(), context)
         outFeat = QgsFeature()
         features = QgsProcessingUtils.getFeatures(vlayer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(vlayer, context)
+        total = 100.0 / vlayer.featureCount() if vlayer.featureCount() else 0
         for current, feature in enumerate(features):
             feedback.setProgress(int(current * total))
             inGeom = feature.geometry()

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

@@ -133,7 +133,7 @@ def processAlgorithm(self, parameters, context, feedback):
         outFeat.setFields(fields)
 
         features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
         for current, f in enumerate(features):
             inGeom = f.geometry()
 

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

@@ -77,7 +77,7 @@ def processAlgorithm(self, parameters, context, feedback):
         end_distance = self.getParameterValue(self.END_DISTANCE)
 
         features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
 
         for current, input_feature in enumerate(features):
             output_feature = input_feature

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

@@ -143,7 +143,7 @@ def layerExtent(self, source, sink, feedback):
 
     def featureExtent(self, source, context, sink, feedback):
         features = source.getFeatures()
-        total = 100.0 / source.featureCount()
+        total = 100.0 / source.featureCount() if source.featureCount() else 0
         feat = QgsFeature()
         for current, f in enumerate(features):
             if feedback.isCanceled():

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

@@ -107,7 +107,7 @@ def processAlgorithm(self, parameters, context, feedback):
 
         selectedSet = []
         features = QgsProcessingUtils.getFeatures(selectLayer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(selectLayer, context)
+        total = 100.0 / selectLayer.featureCount() if selectLayer.featureCount() else 0
         for current, f in enumerate(features):
             geom = vector.snapToPrecision(f.geometry(), precision)
             bbox = geom.boundingBox()
@@ -136,7 +136,7 @@ def processAlgorithm(self, parameters, context, feedback):
             selectedSet = selectedSet + disjoinSet
 
         features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
         for current, f in enumerate(features):
             if f.id() in selectedSet:
                 writer.addFeature(f)

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

@@ -78,7 +78,7 @@ def processAlgorithm(self, parameters, context, feedback):
         writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(fields, QgsWkbTypes.Point, layer.crs(), context)
 
         features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
         for current, f in enumerate(features):
             input_geometry = f.geometry()
             if not input_geometry:

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

@@ -92,7 +92,7 @@ def processAlgorithm(self, parameters, context, feedback):
                     self.tr('\'{}\' is not a valid node index').format(node))
 
         features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
 
         for current, f in enumerate(features):
 

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

@@ -144,7 +144,7 @@ def processAlgorithm(self, parameters, context, feedback):
 
         # Run
         features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
         for current, feat in enumerate(features):
             feedback.setProgress(int(current * total))
             attrs = feat.attributes()

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

@@ -137,7 +137,7 @@ def processAlgorithm(self, parameters, context, feedback):
         calculationSuccess = True
 
         features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
 
         rownum = 1
         for current, f in enumerate(features):

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

@@ -79,7 +79,7 @@ def processAlgorithm(self, parameters, context, feedback):
         if QgsProcessingUtils.featureCount(layer, context) == 0:
             raise GeoAlgorithmExecutionException(self.tr('There are no features in the input layer'))
 
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
         for current, inputFeature in enumerate(features):
             outputFeature = inputFeature
             if inputFeature.geometry():

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

@@ -115,7 +115,7 @@ def processAlgorithm(self, parameters, context, feedback):
                 self.tr('Evaluation error: {0}').format(expression.evalErrorString()))
 
         features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
         for current, input_feature in enumerate(features):
             output_feature = input_feature
 

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

@@ -94,7 +94,7 @@ def processAlgorithm(self, parameters, context, feedback):
         writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(layer.fields(), newType, layer.crs(), context)
 
         features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
 
         for current, f in enumerate(features):
             geom = f.geometry()

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

@@ -84,7 +84,7 @@ def processAlgorithm(self, parameters, context, feedback):
                                                                      context)
 
         features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
 
         for current, f in enumerate(features):
             geom = f.geometry()

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

@@ -174,7 +174,7 @@ def processAlgorithm(self, parameters, context, feedback):
         request = QgsFeatureRequest()
         request.setSubsetOfAttributes(attrs)
         features = QgsProcessingUtils.getFeatures(layer, context, request)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
         for current, f in enumerate(features):
             if kde.addFeature(f) != QgsKernelDensityEstimation.Success:
                 QgsMessageLog.logMessage(self.tr('Error adding feature with ID {} to heatmap').format(f.id()), self.tr('Processing'), QgsMessageLog.CRITICAL)

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

@@ -122,7 +122,7 @@ def processAlgorithm(self, parameters, context, feedback):
 
         # Scan source points, find nearest hub, and write to output file
         features = QgsProcessingUtils.getFeatures(layerPoints, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layerPoints, context)
+        total = 100.0 / layerPoints.featureCount() if layerPoints.featureCount() else 0
         for current, f in enumerate(features):
             src = f.geometry().boundingBox().center()
 

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

@@ -122,7 +122,7 @@ def processAlgorithm(self, parameters, context, feedback):
 
         # Scan source points, find nearest hub, and write to output file
         features = QgsProcessingUtils.getFeatures(layerPoints, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layerPoints, context)
+        total = 100.0 / layerPoints.featureCount() if layerPoints.featureCount() else 0
         for current, f in enumerate(features):
             src = f.geometry().boundingBox().center()
 

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

@@ -92,7 +92,7 @@ def processAlgorithm(self, parameters, context, feedback):
 
         spokes = QgsProcessingUtils.getFeatures(layerSpoke, context)
         hubs = QgsProcessingUtils.getFeatures(layerHub, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layerSpoke, context)
+        total = 100.0 / layerSpoke.featureCount() if layerSpoke.featureCount() else 0
 
         for current, spokepoint in enumerate(spokes):
             p = spokepoint.geometry().boundingBox().center()

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

@@ -114,7 +114,7 @@ def processAlgorithm(self, parameters, context, feedback):
         memRasterDriver = gdal.GetDriverByName('MEM')
 
         features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        total = 100.0 / layer.featureCount() if layer.featureCount() else 0
 
         for current, f in enumerate(features):
             geom = f.geometry()

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

@@ -180,7 +180,7 @@ def processAlgorithm(self, parameters, context, feedback):
                 self.tr('Error importing to PostGIS\n{0}').format(exporter.errorMessage()))
 
         features = source.getFeatures()
-        total = 100.0 / source.featureCount()
+        total = 100.0 / source.featureCount() if source.featureCount() else 0
         for current, f in enumerate(features):
             if feedback.isCanceled():
                 break