Transition to Werkzeug 1.0

Werkzeug originally had a magical import system hook that enabled everything to be imported from one module and still loading the actual implementations lazily as necessary. Unfortunately this turned out to be slow and also unreliable on alternative Python implementations and Google’s App Engine.

Starting with 0.7 we recommend against the short imports and strongly encourage starting importing from the actual implementation module. Werkzeug 1.0 will disable the magical import hook completely.

Because finding out where the actual functions are imported and rewriting them by hand is a painful and boring process we wrote a tool that aids in making this transition.

Automatically Rewriting Imports

For instance, with Werkzeug < 0.7 the recommended way to use the escape function was this:

from werkzeug import escape

With Werkzeug 0.7, the recommended way to import this function is directly from the utils module (and with 1.0 this will become mandatory). To automatically rewrite all imports one can use the werkzeug-import-rewrite script.

You can use it by executing it with Python and with a list of folders with Werkzeug based code. It will then spit out a hg/git compatible patch file. Example patch file creation:

$ python . > new-imports.udiff

To apply the patch one of the following methods work:


hg import new-imports.udiff


git apply new-imports.udiff


patch -p1 < new-imports.udiff

Deprecated and Removed Code

Some things that were relevant to Werkzeug’s core (working with WSGI and HTTP) have been removed. These were not commonly used, or are better served by dedicated libraries.

  • werkzeug.script, replace with Click or another dedicated command line library.
  • werkzeug.template, replace with Jinja or another dedicated template library.
  • werkzeug.contrib.jsrouting, this type of URL generation in JavaScript did not scale well. Instead, generate URLs when rendering templates, or add a URL field to a JSON response.
  • werkzeug.contrib.kickstart, replace with custom code if needed, the Werkzeug API has improved in general. Flask is a higher-level version of this.
  • werkzeug.contrib.testtools, was not significantly useful over the default behavior.
  • werkzeug.contrib.cache, has been extracted to cachelib.
  • werkzeug.contrib.atom, was outside the core focus of Werkzeug, replace with a dedicated feed generation library.
  • werkzeug.contrib.limiter, stream limiting is better handled by the WSGI server library instead of middleware.