Upgrading code from older versions of Quixote

This document lists backward-incompatible changes in Quixote, and explains how to update application code to work with the newer version.

Changes from 2.8 to 2.9

util.randbytes() returns a URL-safe base64 encoded token rather than a hex encoded token. The session module now uses 128-bit random tokens rather than 64-bit.

Changes from 2.7 to 2.8

Stricter handling of HTTP request methods has been enabled. By default only the GET, HEAD, and POST methods are allowed. To enable more methods, change the ALLOWED_METHODS attribute of the config. To disable method checking (i.e. pre-2.8 behavior), set ALLOWED_METHODS to None.

Changes from 1.0 to 2.0

Change any imports you have from quixote.form to be from quixote.form1.

Change any imports you have from quixote.form2 to be from quixote.form.

Replace calls to HTTPRequest.get_form_var() with calls to get_field().

Define a create_publisher() function to get the publisher you need and figure out how you want to connect it to web server. See files in demo and server for examples. Note that publish1.py contains a publisher that works more like the Quixote1 Publisher, and does not require the changes listed below.

Make every namespace be an instance of quixote.directory.Directory. Update namespaces that are modules (or in the init.py of a package) by defining a new class in the module that inherits from Directory and moving your _q_exports and _q_* functions onto the class. Replace "request" parameters with "self" parameters on the new methods. If you have a _q_resolve method, include Resolving in the bases of your new class.

Remove request from calls to _q_ functions. If request, session, user, path, or redirect is used in these new methods, replace as needed with calls to get_request(), get_session(), get_user(), get_path(), and/or redirect(), imported from quixote.

In every namespace that formerly traversed into a module, import the new Directory class from the module and create an instance of the Directory in a variable whose name is the name of the module.

In every namespace with a _q_exports and a _q_index, either add "" to _q_exports or make sure that _q_lookup handles "" by returning the result of a call to _q_index.

If your code depends on the Publisher's namespace_stack attribute, try using quixote.util.get_directory_path() instead. If you need the namespace stack after the traversal, override Directory._q_traverse() to call get_directory_path() when the end of the path is reached, and record the result somewhere for later reference.

If your code depends on _q_exception_handler, override the _q_traverse on your root namespace or on your own Directory class to catch exceptions and handle them the way you want. If you just want a general customization for exception responses, you can change or override Publisher.format_publish_error().

If your code depended on _q_access, include the AccessControlled with the bases of your Directory classes as needed.

Provide imports as needed to htmltext, TemplateIO, get_field, get_request, get_session, get_user, get_path, redirect, ?. You may find dulcinea/bin/unknown.py useful for identifying missing imports.

Quixote 1's secure_errors configuration variable is not present in Quixote 2.

Form.__init__ no longer has name or attrs keywords. If your existing code calls Form.__init__ with 'attrs=foo', you'll need to change it to '**foo'. Form instances no longer have a name attribute. If your code looks for form.name, you can find it with form.attrs.get('name'). The Form.__init__ keyword parameter (and attribute) 'action_url' is now named 'action'.

System Message: WARNING/2 (upgrading.txt, line 82); backlink

Inline strong start-string without end-string.

The SessionPublisher class is gone. Use the Publisher class instead. Also, the 'session_mgr' keyword has been renamed to 'session_manager'.

Changes from 0.6.1 to 1.0

Sessions

A leading underscore was removed from the Session attributes __remote_address, __creation_time, and __access_time. If you have pickled Session objects you will need to upgrade them somehow. Our preferred method is to write a script that unpickles each object, renames the attributes and then re-pickles it.

Changes from 0.6 to 0.6.1

_q_exception_handler now called if exception while traversing

_q_exception_handler hooks will now be called if an exception is raised during the traversal process. Quixote 0.6 had a bug that caused _q_exception_handler hooks to only be called if an exception was raised after the traversal completed.

Changes from 0.5 to 0.6

_q_getname renamed to _q_lookup

The _q_getname special function was renamed to _q_lookup, because that name gives a clearer impression of the function's purpose. In 0.6, _q_getname still works but will trigger a warning.

Form Framework Changes

The quixote.form.form module was changed from a .ptl file to a .py file. You should delete or move the existing quixote/ directory in site-packages before running setup.py, or at least delete the old form.ptl and form.ptlc files.

The widget and form classes in the quixote.form package now return htmltext instances. Applications that use forms and widgets will likely have to be changed to use the [html] template type to avoid over-escaping of HTML special characters.

Also, the constructor arguments to SelectWidget and its subclasses have changed. This only affects applications that use the form framework located in the quixote.form package.

In Quixote 0.5, the SelectWidget constructor had this signature:

def __init__ (self, name, value=None,
              allowed_values=None,
              descriptions=None,
              size=None,
              sort=0):

allowed_values was the list of objects that the user could choose, and descriptions was a list of strings that would actually be shown to the user in the generated HTML.

In Quixote 0.6, the signature has changed slightly:

def __init__ (self, name, value=None,
              allowed_values=None,
              descriptions=None,
              options=None,
              size=None,
              sort=0):

The quote argument is gone, and the options argument has been added. If an options argument is provided, allowed_values and descriptions must not be supplied.

The options argument, if present, must be a list of tuples with 1,2, or 3 elements, of the form (value:any, description:any, key:string).

  • value is the object that will be returned if the user chooses this item, and must always be supplied.
  • description is a string or htmltext instance which will be shown to the user in the generated HTML. It will be passed through the htmlescape() functions, so for an ordinary string special characters such as '&' will be converted to '&'. htmltext instances will be left as they are.
  • If supplied, key will be used in the value attribute of the option element (<option value="...">). If not supplied, keys will be generated; value is checked for a _p_oid attribute and if present, that string is used; otherwise the description is used.

In the common case, most applications won't have to change anything, though the ordering of selection items may change due to the difference in how keys are generated.

File Upload Changes

Quixote 0.6 introduces new support for HTTP upload requests. Any HTTP request with a Content-Type of "multipart/form-data" -- which is generally only used for uploads -- is now represented by HTTPUploadRequest, a subclass of HTTPRequest, and the uploaded files themselves are represented by Upload objects.

Whenever an HTTP request has a Content-Type of "multipart/form-data", an instance of HTTPUploadRequest is created instead of HTTPRequest. Some of the fields in the request are presumably uploaded files and might be quite large, so HTTPUploadRequest will read all of the fields supplied in the request body and write them out to temporary files; the temporary files are written in the directory specified by the UPLOAD_DIR configuration variable.

Once the temporary files have been written, the HTTPUploadRequest object is passed to a function or PTL template, just like an ordinary request. The difference between HTTPRequest and HTTPUploadRequest is that all of the form variables are represented as Upload objects. Upload objects have three attributes:

orig_filename
the filename supplied by the browser.
base_filename
a stripped-down version of orig_filename with unsafe characters removed. This could be used when writing uploaded data to a permanent location.
tmp_filename
the path of the temporary file containing the uploaded data for this field.

Consult upload.txt for more information about handling file uploads.

Refactored Publisher Class

Various methods in the Publisher class were rearranged. If your application subclasses Publisher, you may need to change your code accordingly.

  • parse_request() no longer creates the HTTPRequest object; instead a new method, create_request(), handles this, and can be overridden as required.

    As a result, the method signature has changed from parse_request(stdin, env) to parse_request(request).

  • The Publisher.publish() method now catches exceptions raised by parse_request().

Changes from 0.4 to 0.5

Session Management Changes

The Quixote session management interface underwent lots of change and cleanup with Quixote 0.5. It was previously undocumented (apart from docstrings in the code), so we thought that this was a good opportunity to clean up the interface. Nevertheless, those brave souls who got session management working just by reading the code are in for a bit of suffering; this brief note should help clarify things. The definitive documentation for session management is session-mgmt.txt -- you should start there.

Attribute renamings and pickled objects

Most attributes of the standard Session class were made private in order to reduce collisions with subclasses. The downside is that pickled Session objects will break. You might want to (temporarily) modify session.py and add this method to Session:

def __setstate__ (self, dict):
    # Update for attribute renamings made in rev. 1.51.2.3
    # (between Quixote 0.4.7 and 0.5).
    self.__dict__.update(dict)
    if hasattr(self, 'remote_address'):
        self.__remote_address = self.remote_address
        del self.remote_address
    if hasattr(self, 'creation_time'):
        self.__creation_time = self.creation_time
        del self.creation_time
    if hasattr(self, 'access_time'):
        self.__access_time = self.access_time
        del self.access_time
    if hasattr(self, 'form_tokens'):
        self._form_tokens = self.form_tokens
        del self.form_tokens

However, if your sessions were pickled via ZODB, this may not work. (It didn't work for us.) In that case, you'll have to add something like this to your class that inherits from both ZODB's Persistent and Quixote's Session:

def __setstate__ (self, dict):
    # Blechhh!  This doesn't work if I put it in Quixote's
    # session.py, so I have to second-guess how Python
    # treats "__" attribute names.
    self.__dict__.update(dict)
    if hasattr(self, 'remote_address'):
        self._Session__remote_address = self.remote_address
        del self.remote_address
    if hasattr(self, 'creation_time'):
        self._Session__creation_time = self.creation_time
        del self.creation_time
    if hasattr(self, 'access_time'):
        self._Session__access_time = self.access_time
        del self.access_time
    if hasattr(self, 'form_tokens'):
        self._form_tokens = self.form_tokens
        del self.form_tokens

It's not pretty, but it worked for us.