Building your URLs in cubicweb
In cubicweb, you often have to build url's that redirect the current view to a specific entity view or allow the execution of a given action. Moreover, you often want also to fallback to the previous view once the specific action or edition is done, or redirect also to another entity's specific view.
To do so, cubicweb provides you with a set of powerful tools, however as there is often more than one way to do it, this blog entry is here to help you in choosing the preferred way.
build_url is accessible in any context, so for instance in the rendering of a given entity view you can call self._cw.build_url to build you URLs easily, which is the most common case. In class methods (for instance, when declaring the rendering methods of an EntityTableView), you can access it through the context of instantiated appobject which are usually given as argument, e.g. entity._cw.build_url. For test purposes you can also call session.build_url in cubicweb shells.
build_url basically take a first optional, the path, relative to the base url of the site, and arbitrary named arguments that will be encoded as url parameters. Unless you wish to direct to a custom controller, or to match an URL rewrite url, you don't have to specify the path.
Extra parameters given to build_url will vary according to your needs, however most common arguments understood by default cubicweb views are the followings:
__redirectvid and __redirectpath are used to control redirection after posting a form and are more detailed in the cubicweb documentation, chapter related to the edition control (http://docs.cubicweb.org/devweb/edition/editcontroller.html).
Generally, an entity has two important methods that retrieve its absolute or relative urls:
Passing the rql to the build_url method requires to have a proper RQL expression. To do so, there is a convenience method, printable_rql(), that is accessible in rset resulting from RQL queries. This allows to apply a view to the same result set as the one currently process, simply using rql = self.cw_rset.printable_rql().
There are several ways to get URL of the current view, the canonical one being to use self._cw.relative_path(includeparams=True) which will return the path of the current view relative to the base url of the site (otherwise use self._cw.url(), including parameters or not according to value given as includeparams).
You can also retrieve values given to individual parameters using self._cw.form, eg:
This case often appears when you want to create a link to a startup view or a controller. It the first case, you simply build you URL like this:
The latter case appears when you want to call a controller directly without having to define a form in your view. This can happen for instance when you want to create a URL that will set a relation between 2 objects and do not need any confirmation for that. The URL construction is done like this:
self._cw.build_url('my_controller_id', arg1=value1, arg2=value2, ...)
Any extra arguments passed to the build_url method will be available in the controller as key, values pairs of the self._cw.forms dictionary. This is especially useful when you want to define some kind of hidden attributes but there is not form to put them into.
And, last but not least, a convenient way to get the root URL of the instance:
Get the URL of the outofcontext view of an entity:
link = entity.absolute_url(vid='outofcontext')
Create a link to a given controller then fall back to the current view:
self.w(u'<a href="%s">Click me</a>' % xml_escape( self._cw.build_url('mycontrollerid', arg1=value1, arg2=value2, rql=self.cw_rset.printable_rql(), __redirectvid=self._cw.form.get('vid',''))))
def publish(self, rset): value1, value2 = self._cw.form['arg1'], self._cw.form['arg2'] # do some stuff with value1 and value2 here... raise Redirect(self._cw.build_url(rql=self._cw.form['rql'], vid=self._cw.form['__redirectvid'], __message=_('you message')))
Create a link to add a given entity and relate this entity to the current one with a relation 'child_of', then go back to the current entity's view:
entity = self.cw_rset.get_entity(0,0) self.w(u'<a href="%s">Click me</a>' % xml_escape( self._cw.build_url('add/Mychildentity', __linkto='child_of:%s:object' % entity.eid, __redirectpath=entity.rest_path(), __redirectvid=self._cw.form.get('vid', ''))))
Same example, but we suppose that we are in a multiple rset entity view, and we want to go back afterwards to this view:
entity = self.cw_rset.get_entity(0,0) self.w(u'<a href="%s">Click me</a>' % xml_escape( self._cw.build_url('add/Mychildentity', rql=self.cw_rset.printable_rql(), __linkto='child_of:%s:object' % entity.eid, __redirectvid=self._cw.form.get('vid', ''))))
Create links to all 'menuactions' in a view:
actions = self._cw.vreg['actions'].possible_actions(self._cw, rset=self.cw_rset) action_links = [unicode(self.action_link(x)) for x in actions.get('menuactions', ())] self.w( u' | '.join(action_links))