如何升级适用于python2.6的lxml

Question

I am receiving the following error when running a python script:

Traceback (most recent call last):
  File "/var/scripts/SchoolClosureManager/SchoolClosureManager.py", line 210, in <module>
    runnable.run()
  File "/var/scripts/SchoolClosureManager/SchoolClosureManager.py", line 18, in run
    reporter = SchoolClosureReporter(xml.name)
  File "/var/scripts/SchoolClosureManager/SchoolClosureManager.py", line 40, in __init__
    document = objectify.fromstring(xml, parser)
  File "lxml.objectify.pyx", line 1826, in lxml.objectify.fromstring (src/lxml/lxml.objectify.c:18625)
  File "lxml.etree.pyx", line 2532, in lxml.etree.fromstring (src/lxml/lxml.etree.c:48634)
  File "parser.pxi", line 1536, in lxml.etree._parseMemoryDocument (src/lxml/lxml.etree.c:72156)
ValueError: Unicode strings with encoding declaration are not supported.

I have found this bug report: https://bugs.launchpad.net/lxml/+bug/683069 that basically says that it was a bug and has been Fixed in trunk rev. 79947 Fixed in trunk rev. 79947

Am I able to just update the lxml dist-package?

I'm currently running python2.6.5 on Ubuntu 8.04.

Answer 1

This worked with Ubuntu 11.10; I'm not sure if it will work with Ubuntu 8.04:

sudo apt-get install libxslt1-dev

If you are using virtualenv (which I recommend for safety and flexibility):

# with your virtual environment activated
pip install --upgrade lxml
pip install cssselect   # cssselect has been spun-off into its own project

If not using virtualenv , you could uninstall the Ubuntu package lxml:

sudo apt-get remove python-lxml

and then install the latest lxml package system-wide with:

sudo pip install --upgrade lxml
sudo pip install cssselect

---

Updated to show the method of installation found per a discussion in the comments. Note that this did not solve the ValueError exception the OP was seeing; it only updated the version of lxml.

Note that the pip executable is a Python script, run by a certain installation of Python. It might be possible to use a single pip with many Python installations, but since hard drive space is relatively cheap, most people install one pip executable for each Python installation.

So if you have multiple Python installations on your system, it is important to use the pip executable which is linked to your target Python executable.

In the OP's case

import sys; print(sys.executable)

returned

/usr/local/bin/python2.6

Since a /usr/local/bin/pip existed,

sudo /usr/local/bin/pip install --upgrade lxml
sudo /usr/local/bin/pip install cssselect

were the appropriate commands.

---

To test which version of lxml you are using:

In [38]: import lxml.etree as ET

In [44]: ET.__version__
Out[44]: u'3.2.0'

In [45]: ET.LIBXML_COMPILED_VERSION
Out[46]: (2, 7, 8)

In [47]: ET.LIBXSLT_COMPILED_VERSION
Out[48]: (1, 1, 26)    

---

To check the location of the module you are using:

In [57]: import lxml.etree as ET

In [58]: ET
Out[58]: <module 'lxml.etree' from '/home/unutbu/.virtualenvs/dev/lib/python2.7/site-packages/lxml/etree.so'>