Vjylku

I have a script that creates a multi-distance buffer rings and have managed to migrate it successfully to QGIS 3.4.5. This script requires me to select a layer, and a feature in the layer before I run it, as such:

from math import *

from qgis.core import *

from qgis.utils import iface

from PyQt5.QtCore import *



geom = iface.activeLayer().selectedFeatures()[0].geometry()



start_x = geom.asPoint().x()

start_y = geom.asPoint().y()

sides = 64

radius = 6378137.0  # meters



# create layer

vl = QgsVectorLayer("Polygon", "Distance Buffers", "memory")

pr = vl.dataProvider()



# changes are only possible when editing the layer

vl.startEditing()



# add fields

pr.addAttributes([QgsField("Distance", QVariant.Int), QgsField("Label", QVariant.String)])



distance = [250, 500, 1000, 2000, 3000, 4000, 5000, 10000, 15000, 20000, 25000, 30000, 40000, 50000]

for i in range(len(distance)):

    points = []

    dist = distance[i]

    degrees = 0

    while degrees <= 360:

        degrees = degrees + 360 / sides



        start_lon = start_x * pi / 180

        start_lat = start_y * pi / 180

        bearing = degrees * pi / 180



        end_lat = asin((sin(start_lat) * cos(dist / radius)) + (cos(start_lat) * sin(dist / radius) * cos(bearing)))

        end_lon = start_lon + atan2(sin(bearing) * sin(dist / radius) * cos(start_lat),

                                    cos(dist / radius) - (sin(start_lat) * sin(end_lat)))



        points.append(QgsPointXY(end_lon * 180 / pi, end_lat * 180 / pi))



        fet_name = str(distance[i])

        if distance[i] < 1000:

            label = str(distance[i]) + "m"

        else:

            label = str(distance[i]/1000) + "km"



    # add a feature

    fet = QgsFeature()

    geometry = QgsGeometry.fromPolygonXY([points])

    fet.setGeometry(geometry)

    fet.setAttributes([fet_name,label])

    pr.addFeatures([fet])



# commit to stop editing the layer

vl.commitChanges()



# update layer's extent when new features have been added

# because change of extent in provider is not propagated to the layer

vl.updateExtents()



myDir = QgsProject.instance().readPath("./")

file_name = 'Distance Buffers' + '.shp'

ShapefileDir = myDir + "/Shapefiles/" + file_name



_writer = QgsVectorFileWriter.writeAsVectorFormat(vl, ShapefileDir, "utf-8", driverName="ESRI Shapefile")



# add layer to the legend

name = 'Distance Buffers'

BufferShp = QgsVectorLayer(ShapefileDir,name, 'ogr')

QgsProject.instance().addMapLayer(BufferShp)



# change active layer

lyr = QgsProject.instance().mapLayersByName(name)[0]

iface.setActiveLayer(lyr)

buffer_lyr = iface.activeLayer()



# load preset qgis style file

buffer_lyr.loadNamedStyle("W:/2. SGER-Economics/c. Project Resources/8. GIS/QGIS Style File/Buffer.qml")

buffer_lyr.triggerRepaint()

I have noticed a few strange behaviors:

1. When I 'Add Script to Toolbox', it immediately tries to run the script, rather than just updating the toolbox to include the selected script.




2. After I run it successfully for the first time, I see that the script is now added to my toolbox. However, when I try to run it again, nothing happens. To run it I have to manually open the script in the Processing Script Editor, then Run Script.




3. After the script is added, whenever I start a new instance of QGIS, I get an error message as such:

An error has occurred while executing Python code:

AttributeError: 'NoneType' object has no attribute 'selectedFeatures'
Traceback (most recent call last): File
"C:/PROGRA~1/QGIS3~1.4/apps/qgis-ltr/./python/pluginsprocessingscriptScriptAlgorithmProvider.py",
line 111, in loadAlgorithms
alg = ScriptUtils.loadAlgorithm(moduleName, filePath) File "C:/PROGRA~1/QGIS3~1.4/apps/qgis-ltr/./python/pluginsprocessingscriptScriptUtils.py",
line 68, in loadAlgorithm
spec.loader.exec_module(module) File "", line 728, in exec_module File "", line 219, in _call_with_frames_removed File
"file05Production2. SGER-Economicsc. Project Resources8.
GISQGIS Processing ScriptsBuffer_QGIS3.py", line 6, in
geom = iface.activeLayer().selectedFeatures()[0].geometry() AttributeError: 'NoneType' object has no attribute 'selectedFeatures'

I assume all of this happens because for some reason QGIS is trying to run my script on its own whenever it opens. Is there something wrong with my script or is this a bug with the new QGIS?