Adding vector layer in QGIS with standalone PyCharm script?

Question

I've been struggling with a standalone script in PyCharm, trying to add a vector layer. I've set up PyCharm with Python3.7 to work with QGIS3 using: http://spatialgalaxy.net/2014/10/09/a-quick-guide-to-getting-started-with-pyqgis-on-windows/#ide-example. I've tried tweaking paths in the bat file and script itself based on various posts to no avail.

At this point I am at a loss. I am new to both QGIS and Python.

Below I have provided all code and output. For reference, I am on a Windows 8 laptop.

Script:

import sys
import os
sys.path.append("C:/OSGeo4W64/apps/qgis/python/")
sys.path.append("C:/OSGeo4W64/apps/qgis/python/plugins")
# set path because apparently bat file didn't?
os.environ['QT_QPA_PLATFORM_PLUGIN_PATH'] = 'C:/OSGeo4W64/apps/Qt5/plugins'
from qgis.core import *
from qgis.gui import *
from qgis.utils import *
from PyQt5.QtCore import *
from PyQt5.QtGui import *
print("Import successful")
# Initialize QGIS Application
qgs = QgsApplication([], False)
QgsApplication.setPrefixPath("C:/OSGeo4W64/apps/qgis", True)
QgsApplication.initQgis()
print("QGIS initialized")
pathto = "C:/Users/USER/Documents/Research/bufftest.shp"
layer = QgsVectorLayer(pathto, "bufftest", "ogr")
if not layer.isValid():
 print("Layer fail!")
# Valid file?
print("File Path points to a file: ", os.path.isfile(pathto))
# Valid layer?
print("Output of layer.isValid(): ", layer.isValid())
qgs.exitQgis()

Bat file:

@echo off
SET OSGEO4W_ROOT=C:\OSGeo4W64
call "%OSGEO4W_ROOT%"\bin\o4w_env.bat
call "%OSGEO4W_ROOT%"\bin\qt5_env.bat
call "%OSGEO4W_ROOT%"\bin\py3_env.bat
@echo off
path %PATH%;%OSGEO4W_ROOT%\apps\qgis\bin
path %PATH%;C:\OSGeo4W64\apps\Qt5\bin
path %PATH%;C:\OSGeo4W64\apps\Python37\Scripts
set PYTHONPATH=%PYTHONPATH%;%OSGEO4W_ROOT%\apps\qgis\python
set PYTHONHOME=%OSGEO4W_ROOT%\apps\Python37
set QT_PLUGIN_PATH=%OSGEO4W_ROOT%\apps\qgis\qtplugins;%OSGEO4W_ROOT%\apps\qt5\plugins
start "PyCharm aware of Quantum GIS" /B "C:\Program Files\JetBrains\PyCharm Community Edition 2018年3月1日\bin\pycharm64.exe"

Debug output:

Import successful
QGIS initialized
Layer fail!
File Path points to a file: True
Output of layer.isValid(): False
sys:1: ResourceWarning: unclosed family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('127.0.0.1', 57568), raddr=('127.0.0.1', 57566)>

Process finished with exit code 0

Answer 1

Found a solution here: PyQGIS QgsVectorLayer() Loading Invalid Layer in Standalone Python Script?

Just added the following line:

os.environ['QGIS_PREFIX_PATH'] = 'C:/OSGeo4W64/apps/qgis'