qgis_process list raises exception if processing algorithm provider is activated

[stibu81]

Set up:
Ubuntu 20.04 in docker (see Dockerfile below)
QGIS master from https://qgis.org/ubuntu-nightly, September 18th

When running qgis_process list , the following error appears:

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/qgis/utils.py", line 334, in _startPlugin
plugins[packageName] = package.classFactory(iface)
File "/usr/share/qgis/python/plugins/processing/__init__.py", line 50, in classFactory
from processing.ProcessingPlugin import ProcessingPlugin
File "/usr/lib/python3/dist-packages/qgis/utils.py", line 794, in _import
mod = _builtin_import(name, globals, locals, fromlist, level)
File "/usr/share/qgis/python/plugins/processing/ProcessingPlugin.py", line 48, in <module>
  from processing.gui.ConfigDialog import ConfigOptionsPage
File "/usr/lib/python3/dist-packages/qgis/utils.py", line 794, in _import
mod = _builtin_import(name, globals, locals, fromlist, level)
File "/usr/share/qgis/python/plugins/processing/gui/ConfigDialog.py", line 57, in <module>
  from processing.gui.menus import defaultMenuEntries, menusSettingsGroup
File "/usr/lib/python3/dist-packages/qgis/utils.py", line 794, in _import
mod = _builtin_import(name, globals, locals, fromlist, level)
File "/usr/share/qgis/python/plugins/processing/gui/menus.py", line 45, in <module>
  vectorMenu = iface.vectorMenu().title()
AttributeError: 'NoneType' object has no attribute 'vectorMenu'

../../src/core/qgsmessagelog.cpp:29 : (logMessage) [0ms] 2020-09-18T14:54:38 Couldn't load plugin 'processing' due to an error when calling its classFactory() method[1] Couldn't load plugin 'processing' due to an error when calling its classFactory() method

To reproduce, use the following docker container:

FROM ubuntu:20.04

ENV DEBIAN_FRONTEND noninteractive

RUN apt-get update && \
  apt-get install -y wget gpg tzdata  && \
  echo "deb https://qgis.org/ubuntu-nightly/ focal main" > /etc/apt/sources.list.d/qgis-nightly.list && \
  wget -qO - https://qgis.org/downloads/qgis-2020.gpg.key | gpg --no-default-keyring --keyring gnupg-ring:/etc/apt/trusted.gpg.d/qgis-archive.gpg --import && \
  chmod a+r /etc/apt/trusted.gpg.d/qgis-archive.gpg && \
  apt-get update

RUN apt-get install -y qgis

ENV QT_QPA_PLATFORM offscreen

RUN mkdir -p ~/.local/share/QGIS/QGIS3/profiles/default/QGIS && \
  echo "[PythonPlugins]\nprocessing=true" > ~/.local/share/QGIS/QGIS3/profiles/default/QGIS/QGIS3.ini

The error only occurs, when the last line is included. If not, there is no error, but the Python plugins are not listed.

[agiudiceandrea]

Hi @stibus81, it seems to me this is a regression. The issue was probably introduced inadvertently with PR #38312 and in particular with commit bacf779

I cannot test by myself, but I think you can workaround the issue, waiting for a proper fix, substituting menus.py in your docker container with this patched version https://raw.githubusercontent.com/agiudiceandrea/QGIS/a4d7cca428c50413437131452852433b6bb285cc/python/plugins/processing/gui/menus.py in which I've removed some reference to iface reverting the above commit.

[stibu81]

Hi @agiudiceandrea
You are probably right about this being a regression, since the issue does not appear in QGIS 3.14. I switched to 3.16 because an algorithm that I am using has been implemented in C++. Since this means that I am not using any Python algorithms right now, I don't have an urgent pain right now.

Thanks nevertheless for the workaround. I'll give it a try next week and let you know whether it helped.

[agiudiceandrea]

This is not needed anymore. A proper fix 772181b was merged in master.

I cannot test by myself, but I think you can workaround the issue, waiting for a proper fix, substituting menus.py in your docker container with this patched version https://raw.githubusercontent.com/agiudiceandrea/QGIS/a4d7cca428c50413437131452852433b6bb285cc/python/plugins/processing/gui/menus.py in which I've removed some reference to iface reverting the above commit.

[stibu81]

@agiudiceandrea @nyalldawson Thanks for the fix. It seems, it is not yet in the nightly build, so I copied menus.py from 772181b and this solved the problem for me. I'll try the nightly build again tomorrow.

[stibu81]

I tried with the current nightly build and the problem is solved. Thanks again!