When upgrading from an older version, you might encounter some backwards
webassets API is not stable yet.
ResolverAPI has changed. Rather than being bound to an environment via the constructor, the individual methods now receive a ``ctx` object, which allows access to the environment’s settings.
See the page on implementing resolvers.
Bundle.url()methods no longer accept an environment argument. To work with a Bundle that is not attached to an environment already, use the following syntax instead:
with bundle.bind(env): bundle.build()
Filters can no longer access a
self.envattribute. It has been renamed to
self.ctx, which provides a compatible object.
- Python 2.5 is no longer supported.
- The API of the BaseCache.get() method has changed. It no longer receives
pythonkeyword argument. This only affects you if you have implemented a custom cache class.
django-assets is no longer included! You need to install it’s package separately. See the current development version.
When upgrading, you need to take extra care to rid yourself of the old version of webassets before installing the separate
django-assetspackage. This is to avoid that Python still finds the old
django_assetsmodule that used to be included with
In some cases, even
pip uninstall webassetsis not enough, and old
*.pycfiles are kept around. I recommend that you delete your old webassets install manually from the filesystem. To find out where it is stored, open a Python shell and do:
>>> import webassets >>> webassets <module 'webassets' from '/usr/local/lib/python2.7/dist-packages/webassets/src/webassets/__init__.pyc'>
Some filters now run in debug mode. Specifically, there are two things that deserve mention:
cssrewritenow runs when
debug="merge". This is always what is wanted; it was essentially a bug that this didn’t happen before.
All kinds of compiler-style filters (Sass, less, Coffeescript, JST templates etc). all now run in debug mode. The presence of such a filter causes bundles to be merged even while
In practice, if you’ve been using custom bundle
debugvalues to get such compilers to run, this will continue to work. Though it can now be simplified. Code like this:
Bundle( Bundle('*.coffee', filters='coffeescript', debug=False) filters='jsmin')
can be replaced with:
which has the same effect, which is that during debugging, Coffeescript will be compiled, but not minimized. This also allows you to define bundles that use compilers from within the templates tags, because nesting is no longer necessary.
However, if you need to combine Coffeescript files (or other files needing compiling) with regular CSS or JS files, nesting is still required:
Bundle('*.js' Bundle('*.coffee', filters='coffeescript'), filters='jsmin')
If for some reason you do not want these compilers to run, you may still use a manual
debugvalue to override the behavior. A case where this is useful is the
lessfilter, which can be compiled in the browser:
Bundle('*.less', filters='less', debug=True)
Here, as long as the environment is in debug mode, the bundle will output the source urls, despite the
lessfilter normally forcing a merge.
As part of this new feature, the handling of nested bundle debug values has changed such that in rare cases you may see a different outcome. In the unlikely case that you are using these a lot, the rule is simple: The debug level can only ever be decreased. Child bundles cannot cannot do “more debugging” than their parent, and if
Environment.debug=False, all bundle debug values are effectively ignored.
The internal class names of filters have been renamed. For example,
JSMinFilteris now simply
JSMin. This only affects you if you reference these classes directly, rather than using their id (such as
jsmin), which should be rare.
Removed the previously deprecated
rebuildalias for the
Subtly changed how the
auto_buildsetting affects the
Bundle.build()method: It doesn’t anymore. Instead, the setting now only works on the level of
Bundle.urls(). The new behaviour is more consistent, makes more sense, and simplifies the code.
The main backwards-incompatiblity caused by this is that when
environment.auto_build=False, and you are calling
bundle.build()without specifying an explicit
forceargument, it used to be the case that
force=Truewas assumed, i.e. the bundle was built without looking at the timestamps to see if a rebuild is necessary. Now, the timestamps will be checked, unless
force=Trueis explicitly given.
In case you don’t want to pass
force=True, you can instead also set the
False; without an updater to check timestamps, every
build()call will act as if
Note: This only affects you if you work with the
Bundle.url()methods directly. The behavior of the command line interface, or the template tags is not affected.
The implementation of the
CommandLineEnvironmenthas changed, and each command is now a separate class. If you have been subclassing
CommandLineEnvironmentto override individual command methods like
CommandLineEnvironment.build(), you need to update your code.
JavaMixinhelper class to implement Java-based filters has been removed, and in it’s stead there is now a
JavaToolbase class that can be used.
The code to resolve bundle contents has been refactored. As a result, the behavior of the semi-internal method
Bundle.resolve_contents()has changed slightly; in addition, the
Environment._normalize_source_path()method used mainly by extensions like
Flask-Assetshas been removed. Instead, extensions now need to implement a custom
Environment.absurlmethod has also disappeared, and replacing it can now be done via a custom
Environment.directorynow always returns an absolute path; if a relative path is stored, it is based off on the current working directory. This spares a lot of calls to
os.abspaththroughout the code. If you need the original value you can always use
JST_COMPILERoption of the
jstfilter is set to
False(as opposed to the default value,
None), the templates will now be output as raw strings. Before,
Noneand used the builtin compiler.
The API of the
concat()filter method has changed. Instead of a list of hunks, it is now given a list of 2-tuples of
JSTTemplateFilterbase class has changed API. - concat filter - jst handlebar filters have changed, use concat, base class has changed
There are some significant backwards incompatible changes in this release.
Environment.updaterproperty (corresponds to the
ASSETS_UPDATERsetting) can no longer be set to
"never"in order to disable the automatic rebuilding. Instead, this now needs to be done using
Environment.auto_build, or the corresponding
ASSETS_EXPIRE) option as been renamed to
ASSETS_URL_EXPIRE), and the default value is now
- To disable automatic building, set the new
ASSETS_AUTO_BUILD) option to
False. Before, this was done via the
Environment.updater, which is now deprecated.
Environment.auto_buildis disabled, the API of Bundle.build() now assumes a default value of
forceargument. This should not cause any problems, since it is the only call signature that really makes sense in this case.
- The former
lessfilter, based on the old Ruby version of lessCSS (still available as the 1.x Ruby gems, but no longer developed) has been renamed
rebuildcommand (of the command line mode) has been renamed to
- The command line interface now requires the external dependency
argparseon Python versions 2.6 and before.
argparseis included with Python starting with version 2.7.
PythonLoader.load_bundles()now returns a dict with the bundle names as keys, rather than a list.
- Filters now receive new keyword arguments. The API now officially requires
filters to accept arbitrary
**kwargsfor compatibility with future versions. While the documentation has always suggested
**kwargsbe used, not all builtin filters followed this rule. Your custom filters may need updating as well.
- Filter classes now longer get an auto-generated name. If you have a custom filter and have not explicitly given it a name, you need to do this now if you want to register the filter globally.
django_assetsno longer tries to load a global
assets.pymodule (it will still find bundles defined in application-level
assets.pyfiles). If you want to define bundles in other modules, you now need to list those explicitly in the ASSETS_MODULES setting.
Environment.updaterclass no longer support custom callables. Instead, you need to subclass
BaseUpdater. Nobody is likely to use this feature though.
- The cache is no longer debug-mode only. If you enable
django-assets), the cache will be enabled regardless of the
ASSETS_DEBUGoption. If you want the old behavior, you can easily configure it manually.
Bundle.buildmethod no longer takes the
no_filtersargument. This was always intended for internal use and its existence not advertised, so its removal shouldn’t cause too many problems.
Bundle.buildmethod now returns a list of
FileHunkobjects, rather than a single one. It now works for container bundles (bundles which only have other bundles for children, not files), rather than raising an exception.
rebuildcommand now ignores a
debug=Falsesetting, and forces a build in production mode instead.
django_assets. the semantics of the
debugsetting have changed again. It once again allows you to specifically enable debug mode for the assets handling, irrespective of Django’s own
ASSETS_AUTO_CREATEoption no longer exists. Instead, automatic creation of bundle output files is now bound to the
ASSETS_UPDATERsetting. If it is
False, i.e. automatic updating is disabled, then assets won’t be automatically created either.
- The filter API has changed. Rather than defining an
applymethod and optionally an
is_source_filterattribute, those now have been replaced by
output()methods. As a result, a single filter can now act as both an input and an output filter.
The semantics of the
ASSETS_DEBUGsetting have changed. In 0.1, setting this to
Truemeant enable the django-assets debugging mode. However,
django-assetsnow follows the default Django
ASSETS_DEBUGshould be understood as meaning how to behave when in debug mode. See ASSETS_DEBUG for more information.
ASSETS_AUTO_CREATEnow causes an error to be thrown if due it it being disabled a file cannot be created. Previously, it caused the source files to be linked directly (as if debug mode were active).
This was done due to
Explicit is better than implicit, and for security considerations; people might trusting their comments to be removed. If it turns out to be necessary, the functionality to fall back to source could be added again in a future version through a separate setting.
yui. Instead, you need to explicitly specify which filter you want to use,