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Flask jinja filter `assets` is incompatible with the `pybabel` command and fails to extract translations

See original GitHub issue

There’s a chance I’m using this wrong, but I’m fairly certain this is a bug. If there is a better way to do this, it is certainly non-intuitive. (originally posted to https://github.com/python-babel/flask-babel/issues/108, but this is probably the right place).

My setup

One html file called index.html. I extract with the command

pybabel extract -F babel.cfg --charset=utf=8 -o messages.pot --no-wrap index.html

The file bable.cfg

[jinja2: **.html]
extensions=jinja2.ext.autoescape,jinja2.ext.with_

My env:

(venv) heartsucker@pythagoras:~/Downloads/test$ python --version
Python 3.4.2
(venv) heartsucker@pythagoras:~/Downloads/test$ pip freeze
Babel==2.3.4
click==6.6
Flask==0.11.1
Flask-Babel==0.11.1
itsdangerous==0.24
Jinja2==2.8
MarkupSafe==0.23
pytz==2016.6.1
Werkzeug==0.11.10
(venv) heartsucker@pythagoras:~/Downloads/test$ uname -a
Linux pythagoras 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-2+deb8u3 (2016-07-02) x86_64 GNU/Linux
(venv) heartsucker@pythagoras:~/Downloads/test$

What works

If index.html is this:

<!DOCTYPE html>
<html>
  <head>
       <link rel="stylesheet" href="{{ ASSET_URL }}" />
  </head>
  <body>
    {{ gettext('Test') }}
  </body>
</html>

The messages.pot is this:

# Translations template for PROJECT.
# Copyright (C) 2016 ORGANIZATION
# This file is distributed under the same license as the PROJECT project.
# FIRST AUTHOR <EMAIL@ADDRESS>, 2016.
#
#, fuzzy
msgid ""
msgstr ""
"Project-Id-Version: PROJECT VERSION\n"
"Report-Msgid-Bugs-To: EMAIL@ADDRESS\n"
"POT-Creation-Date: 2016-08-25 21:57+0200\n"
"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
"Language-Team: LANGUAGE <LL@li.org>\n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=utf=8\n"
"Content-Transfer-Encoding: 8bit\n"
"Generated-By: Babel 2.3.4\n"

#: index.html:7
msgid "Test"
msgstr ""

The one string called Test is correctly extracted.

What doesn’t work

If index.html is this:

<!DOCTYPE html>
<html>
  <head>
    {% assets filters="cssmin", output="gen/source.css", "css/normalize.css" %}
       <link rel="stylesheet" href="{{ ASSET_URL }}" />
    {% endassets %}
  </head>
  <body>
    {{ gettext('Test') }}
  </body>
</html>

The messages.pot is this:


# Translations template for PROJECT.
# Copyright (C) 2016 ORGANIZATION
# This file is distributed under the same license as the PROJECT project.
# FIRST AUTHOR <EMAIL@ADDRESS>, 2016.
#
#, fuzzy
msgid ""
msgstr ""
"Project-Id-Version: PROJECT VERSION\n"
"Report-Msgid-Bugs-To: EMAIL@ADDRESS\n"
"POT-Creation-Date: 2016-08-25 21:58+0200\n"
"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
"Language-Team: LANGUAGE <LL@li.org>\n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=utf=8\n"
"Content-Transfer-Encoding: 8bit\n"
"Generated-By: Babel 2.3.4\n"

The one string called Test is not extracted.

Issue Analytics

State:
Created 7 years ago
Comments:8 (3 by maintainers)

Top GitHub Comments

2reactions

bornfreecommented, Oct 10, 2018

Anyone using the compress tag from Jina Assets Compressor (https://github.com/jaysonsantos/jinja-assets-compressor) can use

extensions=jinja2.ext.autoescape,jinja2.ext.with_,jac.extension.CompressorExtension

Otherwise it fails with:

jinja2.exceptions.TemplateSyntaxError: Encountered unknown tag 'compress'.

2reactions

akxcommented, Oct 3, 2016

Hey,

Sorry it’s taken us a while to get back to you.

What’s happening here is that Jinja fails to parse the template with the {% assets %} tag (not a filter; a custom filter wouldn’t cause problems), since the extension that provides it is not loaded.

Unfortunately the Jinja extractor has silent behavior by default, so you don’t get sensible error messages about these cases. (You can add silent=false to the jinja2 section in your babel.cfg to have it fail loudly.)

The easiest fix is to augment your babel.cfg to add the assets extension – I’m not sure how you configure it in your Flask app, so I can’t directly help further:

[jinja2: **.html]
extensions=jinja2.ext.autoescape,jinja2.ext.with_,whatever.import.path.there.is.to.your.assets.extension

Another, slightly more involved but also more DRY and future-proof, way to fix this would be to use a extractor that uses the environment you already set up for the Flask app for Jinja files; this is what my django-i18nkit project does for compatibility with Django-Jinja: https://github.com/akx/django-i18nkit/blob/master/i18nkit/jinja2_extract.py

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