Python macros QGIS, change directory up

Question

I wish to change the directory of a file up of one level in the QGIS Macros. I tried this code but I got the Error:

File "", line 10, in openProject
TypeError: cdUp(self): first argument of unbound method must have type 'QDir'

my script :

from PyQt5 import *
from PyQt5.QtCore import QDir
def openProject():
 from qgis.core import QgsProject
 old_root_folder = "/home/qgis/base/1_QGISData"
 proj_root = QgsProject.instance().homePath()
 proj_files_folder = "/1_QGIS_Projetdata/"
 new_root_folder = QDir.cdUp(proj_root) + proj_files_folder
 print(new_root_folder)
 for layer in QgsProject.instance().mapLayers().values():
 name = layer.name()
 old_url = layer.dataProvider().dataSourceUri()
 new_url = old_url.replace(old_root_folder, new_root_folder)
 provider = layer.providerType()
 options = layer.dataProvider().ProviderOptions()
 layer.setDataSource(new_url, name, provider, options)
def saveProject():
 pass
def closeProject():
 pass

What do I do wrong?

PS: The proj_files_folder is in a totally different directory

Answer 1

One issue is that QDir.cdUp(proj_root) will only return a bool not a string or path. If you import os and use the split and join functions it may be easier. Using os.path.dirname(your_path_here) will get the parent directory. An example below.

import os
from PyQt5 import *
from PyQt5.QtCore import QDir
def openProject():
 proj_root = QgsProject.instance().homePath()
 cur_path = QDir.currentPath()
 print(cur_path)
 print(proj_root)
 proj_files_folder = "/1_QGIS_Projetdata/"
 bool_change = QDir.cdUp(QDir(cur_path))
 print(bool_change)
 print(QDir.currentPath())
 
 parent = os.path.dirname(cur_path)
 print(parent)
 data_dir = os.path.join(parent, proj_files_folder)
 print(data_dir)
openProject()