7

I'm attempting to save a polygon created in a scratch layer to a shapefile. The Python code below is a simplified example. Note the questions: Saving layer as shapefile using PyQGIS and Setting QgsVectorFileWriter.SaveVectorOptions for QGIS 3 provided some of the help, which I'm including in this post for future reference,

# Attach libraries
from qgis.core import * # attach main QGIS library
from qgis.utils import * # attach main python library
import os # attach operating system library

Set the working directory


wd = "C:/test" # Set work directory
os.chdir(wd) # Change the directory


Set a variable for the current project instance


Prj = QgsProject().instance() # Object for current project


Save the project to this file name


pnm = "Test.qgs" # Project file name
pnm = wd + "/" + pnm # Concat. with path
Prj.write(pnm) # Save the project


Create an array [] object with the polygon vertices


vrtcs = []
vrtcs.append(QgsPointXY(396100,8969000))
vrtcs.append(QgsPointXY(396100,8973900))
vrtcs.append(QgsPointXY(397900,8973900))
vrtcs.append(QgsPointXY(397900,8969000))


Create a polygon from the vertices


ply_01 = QgsGeometry.fromPolygonXY([vrtcs])


Create a feature object then append the polygon into


ftr = QgsFeature()
ftr.setGeometry(ply_01)
print(ftr.geometry())


Create a layer for the feature and add to the project


lyr = QgsVectorLayer('Polygon?crs=epsg:29194','Test',"memory")
Prj.addMapLayers([lyr])


Make the layer editable, add the feature and save


lyr.startEditing()
lyr.addFeature(ftr)
lyr.commitChanges()


Save as a shapefile


Fl_ou = 'Test.shp'
Fl_ou = wd + '/' + Fl_ou
writer = QgsVectorFileWriter(lry, Fl_ou,'urf-8','ESRI Shapefile')

When I execute the last line I get the following error "NameError: name 'lry' is not defined".

However, when I enter type(lyr) into the console it recognizes the variable lyr as a <class 'qgis._core.QgsVectorLayer'> so I am unsure why I'm getting the not defined error.

Taras
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user2627043
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  • You are correct about the typo - but when corrected to lyr now get the error 'TypeError: QgsVectorFileWriter(): argument 1 has unexpected type 'QgsVectorLayer''. I'm guessing the first argument was expecting a string, not an object but when I change argument 1 to 'Test' (the name of the layer) the console reports a new error 'QgsVectorFileWriter(): argument 3 has unexpected type 'str'. Nothing like a nice game of snakes and ladders! Any ideas? – user2627043 Sep 15 '20 at 08:50
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    Which QGIS version do you have? 'urf-8' should be 'utf-8' – BERA Sep 15 '20 at 09:05
  • "https://rest.isric.org/soilgrids/v2.0/properties/query?lon=34.5&lat=1.299" – Taras Apr 08 '22 at 07:33

2 Answers2

10

Use writeAsVectorFormatV2 method of QgsVectorFileWriter class.

# Attach libraries
from qgis.core import * # attach main QGIS library
from qgis.utils import * # attach main python library
import os # attach operating system library

Set the working directory


wd = "C:/test" # Set work directory
os.chdir(wd) # Change the directory


Set a variable for the current project instance


Prj = QgsProject().instance() # Object for current project


Save the project to this file name


pnm = "Test.qgs" # Project file name
pnm = wd + "/" + pnm # Concat. with path
Prj.write(pnm) # Save the project


Create an array [] object with the polygon vertices


vrtcs = []
vrtcs.append(QgsPointXY(396100,8969000))
vrtcs.append(QgsPointXY(396100,8973900))
vrtcs.append(QgsPointXY(397900,8973900))
vrtcs.append(QgsPointXY(397900,8969000))


Create a polygon from the vertices


ply_01 = QgsGeometry.fromPolygonXY([vrtcs])


Create a feature object then append the polygon into


ftr = QgsFeature()
ftr.setGeometry(ply_01)
print(ftr.geometry())


Create a layer for the feature and add to the project


lyr = QgsVectorLayer('Polygon?crs=epsg:29194','Test',"memory")
Prj.addMapLayers([lyr])


Make the layer editable, add the feature and save


lyr.startEditing()
lyr.addFeature(ftr)
lyr.commitChanges()


Save as a shapefile


Fl_ou = 'Test.shp'
Fl_ou = wd + '/' + Fl_ou


options = QgsVectorFileWriter.SaveVectorOptions()
options.driverName = "ESRI Shapefile"


QgsVectorFileWriter.writeAsVectorFormatV2(lyr, Fl_ou, QgsCoordinateTransformContext(), options)
Kadir Şahbaz
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-2

I understand this is an old post, but I developed a plugin that saves all vector layers as .gpkg. All temporary layers are automatically made permanent. Want to share if it can be of use: https://plugins.qgis.org/plugins/SaveAllScript/

CaptainDang
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