Port delete columns alg to new API

Author: nyalldawson

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

@@ -26,11 +26,12 @@
 __revision__ = '$Format:%H$'
 
 from qgis.core import (QgsApplication,
-                       QgsProcessingUtils)
+                       QgsProcessingUtils,
+                       QgsProcessingParameterFeatureSource,
+                       QgsProcessingParameterFeatureSink,
+                       QgsProcessingParameterTableField,
+                       QgsProcessingOutputVectorLayer)
 from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
-from processing.core.parameters import ParameterVector
-from processing.core.parameters import ParameterTableField
-from processing.core.outputs import OutputVector
 
 
 class DeleteColumn(QgisAlgorithm):
@@ -53,11 +54,14 @@ def group(self):
 
     def __init__(self):
         super().__init__()
-        self.addParameter(ParameterVector(self.INPUT,
-                                          self.tr('Input layer')))
-        self.addParameter(ParameterTableField(self.COLUMNS,
-                                              self.tr('Fields to delete'), self.INPUT, multiple=True))
-        self.addOutput(OutputVector(self.OUTPUT, self.tr('Output layer')))
+
+        self.addParameter(QgsProcessingParameterFeatureSource(self.INPUT, self.tr('Input layer')))
+        self.addParameter(QgsProcessingParameterTableField(self.COLUMNS,
+                                                           self.tr('Fields to delete'),
+                                                           None, self.INPUT, QgsProcessingParameterTableField.Any, True))
+
+        self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, self.tr('Output layer')))
+        self.addOutput(QgsProcessingOutputVectorLayer(self.OUTPUT, self.tr("Output layer")))
 
     def name(self):
         return 'deletecolumn'
@@ -66,10 +70,10 @@ def displayName(self):
         return self.tr('Delete column')
 
     def processAlgorithm(self, parameters, context, feedback):
-        layer = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT), context)
+        source = self.parameterAsSource(parameters, self.INPUT, context)
+        fields_to_delete = self.parameterAsFields(parameters, self.COLUMNS, context)
 
-        fields_to_delete = self.getParameterValue(self.COLUMNS).split(';')
-        fields = layer.fields()
+        fields = source.fields()
         field_indices = []
         # loop through twice - first we need to build up a list of original attribute indices
         for f in fields_to_delete:
@@ -83,18 +87,22 @@ def processAlgorithm(self, parameters, context, feedback):
         for index in field_indices:
             fields.remove(index)
 
-        writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(fields, layer.wkbType(), layer.crs(), context)
+        (sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
+                                               fields, source.wkbType(), source.sourceCrs())
 
-        features = QgsProcessingUtils.getFeatures(layer, context)
-        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
+        features = source.getFeatures()
+        total = 100.0 / source.featureCount()
 
         for current, f in enumerate(features):
+            if feedback.isCanceled():
+                break
+
             attributes = f.attributes()
             for index in field_indices:
                 del attributes[index]
             f.setAttributes(attributes)
-            writer.addFeature(f)
+            sink.addFeature(f)
 
             feedback.setProgress(int(current * total))
 
-        del writer
+        return {self.OUTPUT: dest_id}

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

@@ -86,7 +86,7 @@
 # from .Union import Union
 # from .DensifyGeometriesInterval import DensifyGeometriesInterval
 # from .SpatialJoin import SpatialJoin
-# from .DeleteColumn import DeleteColumn
+from .DeleteColumn import DeleteColumn
 # from .DeleteHoles import DeleteHoles
 # from .DeleteDuplicateGeometries import DeleteDuplicateGeometries
 # from .TextToFloat import TextToFloat
@@ -216,7 +216,7 @@ def getAlgs(self):
         #         RandomExtractWithinSubsets(), ExtractByLocation(),
         #         SpatialJoin(), RegularPoints(), SymmetricalDifference(),
         #         VectorSplit(), VectorGridLines(), VectorGridPolygons(),
-        #         DeleteColumn(), DeleteDuplicateGeometries(), TextToFloat(),
+        #         DeleteDuplicateGeometries(), TextToFloat(),
         #         ExtractByAttribute(), SelectByAttribute(), GridPolygon(),
         #         GridLine(), Gridify(), HubDistancePoints(),
         #         HubDistanceLines(), HubLines(), Merge(),
@@ -264,7 +264,9 @@ def getAlgs(self):
                 AutoincrementalField(),
                 Boundary(),
                 BoundingBox(),
-                Clip()]
+                Clip(),
+                DeleteColumn()
+                ]
 
         if hasPlotly:
             #     from .VectorLayerHistogram import VectorLayerHistogram

python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml

@@ -1577,30 +1577,30 @@ tests:
 #        type: vector
 #    results: {}
 #
-#  - algorithm: qgis:deletecolumn
-#    name: Delete columns (multiple)
-#    params:
-#      COLUMN: floatval;name
-#      INPUT:
-#        name: polys.gml
-#        type: vector
-#    results:
-#      OUTPUT:
-#        name: expected/delete_columns.gml
-#        type: vector
-#
-#  - algorithm: qgis:deletecolumn
-#    name: Delete columns (single)
-#    params:
-#      COLUMN: intval
-#      INPUT:
-#        name: polys.gml
-#        type: vector
-#    results:
-#      OUTPUT:
-#        name: expected/delete_column.gml
-#        type: vector
-#
+  - algorithm: qgis:deletecolumn
+    name: Delete columns (multiple)
+    params:
+      COLUMN: floatval;name
+      INPUT:
+        name: polys.gml
+        type: vector
+    results:
+      OUTPUT:
+        name: expected/delete_columns.gml
+        type: vector
+
+  - algorithm: qgis:deletecolumn
+    name: Delete columns (single)
+    params:
+      COLUMN: intval
+      INPUT:
+        name: polys.gml
+        type: vector
+    results:
+      OUTPUT:
+        name: expected/delete_column.gml
+        type: vector
+
 #  - algorithm: qgis:createpointslayerfromtable
 #    name: Create points from table
 #    params: