mtl_gis_oo/scrub_layer_class.py

from qgis.core import *
from qgis.analysis import QgsNativeAlgorithms


class ScrubLayer:
  def __init__(self, qgis_path, layer_path, layer_name):
    # Set the path to QGIS installation
    QgsApplication.setPrefixPath(qgis_path, True)

    # Initialize QGIS application
    qgs = QgsApplication([], False)
    qgs.initQgis()

    self.layer_path = layer_path
    self.layer_name = layer_name
    self.layer = self.load_layer()

  def load_layer(self):
    the_layer = QgsVectorLayer(self.layer_path, self.layer_name, 'ogr')
    if not the_layer.isValid():
      raise ValueError(f'Failed to load layer {self.layer_name} from {self.layer_path}')
    else:
      QgsProject.instance().addMapLayer(the_layer)
    return the_layer

  @staticmethod
  def cleanup():
    QgsApplication.exitQgis()


if __name__ == '__main__':
  app_path = 'C:/Program Files/QGIS 3.34.1/apps/qgis'
  new_path = 'C:/Users/a_adli/PycharmProjects/hydroquebec_archetype_gispy/' \
             'data/test_data/mtl_north/test_north_mtl.shp'
  data_layer_name = 'mtl_north'
  handle_layer = ScrubLayer(app_path, new_path, 'mtl_north')
  print(handle_layer.layer.featureCount())