I’m working on a Python project that needs to run as root in order to work properly. Previously I’ve just run the whole PyCharm IDE as root, but this has some down-sides, and I think I have a better approach now.
While hooking up SQLAlchemy for a web project, I kept running into attribute errors for ‘session_registry’. I figured I was doing something wrong, so I thought I’d just walk through the tutorial as a sanity check.
I was, apparently, insane.
>>> u = session.query(User).filter_by(name='ed').first() Traceback (most recent call last): File "", line 1, in File "C:\dev\misc\SundanceAPI\sapi_env\lib\site-packages\sqlalchemy\orm\query.py", line 2282, in first ret = list(self[0:1]) File "C:\dev\misc\SundanceAPI\sapi_env\lib\site-packages\sqlalchemy\orm\query.py", line 2149, in __getitem__ return list(res) File "C:\dev\misc\SundanceAPI\sapi_env\lib\site-packages\sqlalchemy\orm\query.py", line 2349, in __iter__ context = self._compile_context() File "C:\dev\misc\SundanceAPI\sapi_env\lib\site-packages\sqlalchemy\orm\query.py", line 2702, in _compile_context context = QueryContext(self) File "C:\dev\misc\SundanceAPI\sapi_env\lib\site-packages\sqlalchemy\orm\query.py", line 3247, in __init__ self.session = query.session_registry AttributeError: 'Query' object has no attribute 'session_registry'
Tom Christensen, after joining me in some head scratching, noticed that I was on the 64-bit build of Python, and wondered if there could be anything strange with that.
Googling, we found:
TODO: Still valid? The ez_setup.py script currently(?) installs a broken version of setuptools on 64-bit Windows systems.
TODO: Still valid? To work around this you need to manually download SQLAlchemy and extract it. When extracted you need to copy the <top_dir>/lib/sqlalchemy directory into your Python<version>\Lib\site-packages directory.
Sure enough, following that work-around got rid of the errors. So thanks, openlp guys. In the end, I swapped my virtual environment out for the 32-bit variety. It feels safer there.
About a year ago, I set out to get a solid working understanding of Python packaging, resulting in a lengthy blog post of what I learned. There have been some significant course changes over that year such that my original post is wrong in several regards.
Python 3.3 includes a built-in equivalent to the popular virtualenv tool for creating isolated Python environments. One difference with the built-in venv is that it doesn’t automatically install pip as virtualenv does. While I can understand the decision (given Python’s volatile packaging situation), it isn’t very convenient.
Here’s a Windows batch file that will remedy that, using the latest recommended way of getting pip. It depends on having curl in your path somewhere. Use it like you would virtualenv or venv, namely, by providing the path to where you’d like to create your new virtual environment.
@echo off REM Python 3.3 pyvenv including pip. REM See https://python-packaging-user-guide.readthedocs.org/en/latest/setup.html if "%1" == "" goto :error python -m venv %1 call %1\Scripts\activate curl -O https://bitbucket.org/pypa/setuptools/raw/bootstrap/ez_setup.py python ez_setup.py curl -O https://raw.github.com/pypa/pip/master/contrib/get-pip.py python get-pip.py del ez_setup.py del get-pip.py del setuptools-*.tar.gz goto :EOF :error echo Specify the path to the virtual environment you want to create. echo venv my_env
IMPORTANT: Some of the information in this post is now obsolete. Please see here.
Randomly take a couple of words from the following list, put them together, and there’s a decent chance you’ll come up with something real involving Python packaging.
The packaging situation is kind of confusing with all the alternate tools, libraries and methods, so I’m going to take a stab at clarifying things — for how it seems right now, anyway.
Wouldn’t it be nice to be able to save nice clean HTML from Microsoft Word? Here’s a way that is only slightly convoluted.
I’ve been doing some work with Linux lately, a new thing for me, and feel a bit like I’ve been thrown into the deep end and told to swim. Today I updated Python to version 2.7 on an EC2 instance.