Retrieve path and file name of current qgis project in python

Question

Is there a way to get the path and the file name of the current project from a python script? I'm currently trying to develop a python plugin for qgis and I need to create a file with a similar name in the same folder.

Answer 1

You can use the following method from the QgsProject class to retrieve the path to the project file:

from qgis.core import *
prjpath = QgsProject.instance().fileName()

If there is no project loaded, or the current project has not yet been saved, this will return an empty QString:

PyQt4.QtCore.QString(u'')

You can convert the project file path further to a Python Unicode string (if needed) with:

unicode(prjpath)

However, if you intend to have your plugin be cross-platform, you are better off not working with the file path as a string in Python, but leverage Qt's excellent QFileInfo class:

from PyQt4.QtCore import *
from qgis.core import *

prjfi = QFileInfo(QgsProject.instance().fileName())
prjfi.absolutePath()  # what you are probably looking for

The QFileInfo class (along with QFile and QDir) will handle many cross-platform filesystem issues for you, and inclusively provide methods that would otherwise be spread across more Python classes.