URL publishing

(cubicweb.web.views.urlpublishing)

Associate url’s path to view identifier / rql queries.

CubicWeb finds all registered URLPathEvaluators, orders them according to their priority attribute and calls their evaluate_path() method. The first that returns something and doesn’t raise a PathDontMatch exception wins.

Here is the default evaluator chain:

  1. cubicweb.web.views.urlpublishing.RawPathEvaluator handles unique url segments that match exactly one of the registered controller’s __regid__. Urls such as /view?, /edit?, /json? fall in that category;
  2. cubicweb.web.views.urlpublishing.EidPathEvaluator handles unique url segments that are eids (e.g. /1234);
  3. cubicweb.web.views.urlpublishing.URLRewriteEvaluator selects all urlrewriter components, sorts them according to their priority, call their rewrite() method, the first one that doesn’t raise a KeyError wins. This is where the cubicweb.web.views.urlrewrite and cubicweb.web.views.urlrewrite.SimpleReqRewriter comes into play;
  4. cubicweb.web.views.urlpublishing.RestPathEvaluator handles urls based on entity types and attributes : <etype>((/<attribute name>])?/<attribute value>)? This is why cwuser/carlos works;
  5. cubicweb.web.views.urlpublishing.ActionPathEvaluator handles any of the previous paths with an additional trailing “/<action>” segment, <action> being one of the registered actions’ __regid__.

Note

Actionpath executes a query whose results is lost because of redirecting instead of direct traversal.

class cubicweb.web.views.urlpublishing.URLPublisherComponent(vreg, default_method='view')[source]

Associate url path to view identifier / rql queries, by applying a chain of urlpathevaluator components.

An evaluator is a URLPathEvaluator subclass with an .evaluate_path method taking the request object and the path to publish as argument. It will either return a publishing method identifier and an rql query on success or raise a PathDontMatch exception on failure. URL evaluators are called according to their priority attribute, with 0 as the greatest priority and greater values as lower priority. The first evaluator returning a result or raising something else than PathDontMatch will stop the handlers chain.

process(req, path)[source]

Given a URL (essentially characterized by a path on the server, but additional information may be found in the request object), return a publishing method identifier (e.g. controller) and an optional result set.

Parameters:
  • req (cubicweb.web.request.CubicWebRequestBase) – the request object
  • path (str) – the path of the resource to publish. If empty, None or “/” “view” is used as the default path.
Return type:

tuple(str, cubicweb.rset.ResultSet or None)

Returns:

the publishing method identifier and an optional result set

Raises NotFound:
 

if no handler is able to decode the given path

You can write your own URLPathEvaluator class to handle custom paths. For instance, if you want /my-card-id to redirect to the corresponding card’s primary view, you would write:

class CardWikiidEvaluator(URLPathEvaluator):
    priority = 3 # make it be evaluated *before* RestPathEvaluator

    def evaluate_path(self, req, segments):
        if len(segments) != 1:
            raise PathDontMatch()
        rset = req.execute('Any C WHERE C wikiid %(w)s',
                           {'w': segments[0]})
        if len(rset) == 0:
            # Raise NotFound if no card is found
            raise PathDontMatch()
        return None, rset

On the other hand, you can also deactivate some of the standard evaluators in your final application. The only thing you have to do is to unregister them, for instance in a registration_callback in your cube:

def registration_callback(vreg):
    vreg.unregister(RestPathEvaluator)

You can even replace the cubicweb.web.views.urlpublishing.URLPublisherComponent class if you want to customize the whole toolchain process or if you want to plug into an early enough extension point to control your request parameters:

class SanitizerPublisherComponent(URLPublisherComponent):
    """override default publisher component to explicitly ignore
    unauthorized request parameters in anonymous mode.
    """
    unauthorized_form_params = ('rql', 'vid', '__login', '__password')

    def process(self, req, path):
        if req.session.anonymous_session:
            self._remove_unauthorized_params(req)
        return super(SanitizerPublisherComponent, self).process(req, path)

    def _remove_unauthorized_params(self, req):
        for param in req.form.keys():
            if param in self.unauthorized_form_params:
                 req.form.pop(param)


def registration_callback(vreg):
    vreg.register_and_replace(SanitizerPublisherComponent, URLPublisherComponent)
class cubicweb.web.views.urlpublishing.RawPathEvaluator(urlpublisher)[source]

handle path of the form:

<publishing_method>?parameters...
class cubicweb.web.views.urlpublishing.EidPathEvaluator(urlpublisher)[source]

handle path with the form:

<eid>
class cubicweb.web.views.urlpublishing.URLRewriteEvaluator(urlpublisher)[source]

tries to find a rewrite rule to apply

URL rewrite rule definitions are stored in URLRewriter objects

class cubicweb.web.views.urlpublishing.RestPathEvaluator(urlpublisher)[source]

handle path with the form:

<etype>[[/<attribute name>]/<attribute value>]*
class cubicweb.web.views.urlpublishing.ActionPathEvaluator(urlpublisher)[source]

handle path with the form:

<any evaluator path>/<action>

URL rewriting

(cubicweb.web.views.urlrewrite)

class cubicweb.web.views.urlrewrite.URLRewriter(req, **extra)[source]

Base class for URL rewriters.

Url rewriters should have a rules dict that maps an input URI to something that should be used for rewriting.

The actual logic that defines how the rules dict is used is implemented in the rewrite method.

A priority attribute might be used to indicate which rewriter should be tried first. The higher the priority is, the earlier the rewriter will be tried.

class cubicweb.web.views.urlrewrite.SimpleReqRewriter(req, **extra)[source]

The SimpleReqRewriters uses a rules dict that maps input URI (regexp or plain string) to a dictionary to update the request’s form.

If the input uri is a regexp, group substitution is allowed.

rewrite(req, uri)[source]

for each input, output `in rules, if `uri matches input, req’s form is updated with output

class cubicweb.web.views.urlrewrite.SchemaBasedRewriter(req, **extra)[source]

Here, the rules dict maps regexps or plain strings to callbacks that will be called with inputurl, uri, req, schema as parameters.

SimpleReqRewriter is enough for a certain number of simple cases. If it is not sufficient, SchemaBasedRewriter allows to do more elaborate things.

Here is an example of SimpleReqRewriter usage with plain string:

from cubicweb.web.views.urlrewrite import SimpleReqRewriter
class TrackerSimpleReqRewriter(SimpleReqRewriter):
    rules = [
     ('/versions', dict(vid='versionsinfo')),
     ]

When the url is <base_url>/versions, the view with the __regid__ versionsinfo is displayed.

Here is an example of SimpleReqRewriter usage with regular expressions:

from cubicweb.web.views.urlrewrite import (
    SimpleReqRewriter, rgx)

class BlogReqRewriter(SimpleReqRewriter):
    rules = [
        (rgx('/blogentry/([a-z_]+)\.rss'),
         dict(rql=('Any X ORDERBY CD DESC LIMIT 20 WHERE X is BlogEntry,'
                   'X creation_date CD, X created_by U, '
                   'U login "%(user)s"'
                   % {'user': r'\1'}), vid='rss'))
        ]

When a url matches the regular expression, the view with the __regid__ rss which match the result set is displayed.

Here is an example of SchemaBasedRewriter usage:

from cubicweb.web.views.urlrewrite import (
    SchemaBasedRewriter, rgx, build_rset)

class TrackerURLRewriter(SchemaBasedRewriter):
    rules = [
        (rgx('/project/([^/]+)/([^/]+)/tests'),
         build_rset(rql='Version X WHERE X version_of P, P name %(project)s, X num %(num)s',
                    rgxgroups=[('project', 1), ('num', 2)], vid='versiontests')),
        ]

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