# Listing project layers in standalone PyQGIS script

I'm trying to load an existing .qgs project and get a list of the layers inside. I seem to be able to open the project, but I can't get the list of layers. I'm a little confused as to the basic PyQGIS syntax, and the cookbook doesn't cover this specific example.

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

QgsApplication.setPrefixPath(r"C:\OSGeo4W\apps\qgis-ltr", True)
qgs = QgsApplication([], False)
qgs.initQgis()
# Get the project instance
project = QgsProject.instance()
# Open the project
r'C:\path\to\project\project.qgs'))
print project.fileName()
# Get the layers in the project
layers = QgsMapLayerRegistry.instance().mapLayers()

print layers
qgs.exitQgis()


Currently, this just layers returns an empty dict, despite the fact that the project exists and has many layers in it.

• I have the same problem in QGIS 2.18.2 tried steps of OP and @GermánCarrillo. What's OP's version? Dec 28, 2016 at 18:47
• I was using QGIS 2.16.2 on Windows 7x64 at the time. Have since tried on 2.18.2 and still did not work. Dec 28, 2016 at 20:35
• I flagged this question for reopening because the linked question applies to within QGIS, but the solution doesn't work in a standalone Python script Dec 30, 2016 at 18:36
• Have you tried: layers = QgsMapLayerRegistry.instance().mapLayers().keys() Jan 4, 2017 at 15:42
• Can you try to insert QgsApplication.processEvents() right after project.read? Jan 5, 2017 at 7:23

I also receive an empty dictionary when I run your code but the following works for me which is slightly different:

from qgis.core import *
from PyQt4.QtCore import QFileInfo
from PyQt4.QtGui import QApplication
import os

from os.path import expanduser
home = expanduser("~")

QgsApplication( [], False, home + "/AppData/Local/Temp" )
QgsApplication.setPrefixPath("C:/OSGeo4W64/apps/qgis", True)
app = QApplication([], True)
QgsApplication.initQgis()

# Get the project instance
project = QgsProject.instance()
# Open the project
print project.fileName()
# Get the layers in the project
layers = QgsMapLayerRegistry.instance().mapLayers()
print layers

QgsApplication.exitQgis()
app.exit()


Tested on QGIS 2.18.3 for Windows 7 64-bit.

Edit:

The main difference, I believe, between your code and what I used is that you need to create the QApplication object before creating the QgsApplication. So you would need to replace:

qgs = QgsApplication([], False)


with this:

qgs = QApplication([], False)


But the QApplication class needs to be imported so we must add the following:

from PyQt4.QtGui import QApplication


And finally, if you want to do a cleanup, you need to add the following at the end.

QgsApplication.exitQgis()


So you could try using the following code which is more close to your original code:

from qgis.core import *
from PyQt4.QtCore import QFileInfo
from PyQt4.QtGui import QApplication

QgsApplication.setPrefixPath("C:/OSGeo4W64/apps/qgis", True)
qgs = QApplication([], False)
QgsApplication.initQgis()
# Get the project instance
project = QgsProject.instance()
# Open the project