Source code for kotti.views.slots

"""This module allows add-ons to assign views to slots defined in
the overall page.  In other systems, these are called portlets or
viewlets.

A simple example that'll include the output of the 'hello_world' view
in in the left column of every page::

  from kotti.views.slots import assign_slot
  assign_slot('hello_world', 'left')

It is also possible to pass parameters to the view::

  assign_slot('last_tweets', 'right', params=dict(user='foo'))

In the view you can get the slot in that the view is rendered from
the request::

    @view_config(name='last_tweets')
    def view(request, context):
        slot = request.kotti_slot
        # ...

If no view can be found for the given request and slot, the slot
remains empty.  If you want to force your slot not to be rendered,
raise :class:`pyramid.exceptions.PredicateMismatch` inside your view::

    from pyramid.exceptions import PredicateMismatch

    @view_config(name='last_tweets')
    def view(request, context):
        if some_condition:
            raise PredicateMismatch()
        return {...}

Usually you'll want to call :func:`kotti.views.slots.assign_slot`
inside an ``includeme`` function and not on a module level, to allow
users of your package to include your slot assignments through the
``pyramid.includes`` configuration setting.
"""

import urllib

from pyramid.exceptions import PredicateMismatch
from pyramid.request import Request
from pyramid.view import render_view

from kotti.events import ObjectEvent
from kotti.events import objectevent_listeners

REQUEST_ATTRS_TO_COPY = ('context', 'registry', 'user', 'cookies', 'session')


def _encode(params):
    if not params:
        return u''
    return urllib.urlencode(
        dict((k, v.encode('utf-8')) for k, v in params.items()))


def _render_view_on_slot_event(view_name, event, params):
    context = event.object
    request = event.request

    view_request = Request.blank(
        "{0}/{1}".format(request.path.rstrip('/'), view_name),
        base_url=request.application_url,
        POST=_encode(params))

    post_items = request.POST.items()
    if post_items:
        view_request.POST.extend(post_items)

    # This is quite brittle:
    for name in REQUEST_ATTRS_TO_COPY:
        setattr(view_request, name, getattr(request, name))
    setattr(view_request, 'kotti_slot', event.name)

    try:
        result = render_view(context, view_request, view_name)
    except PredicateMismatch:
        return None
    else:
        return result.decode('utf-8')


[docs]def assign_slot(view_name, slot, params=None): """Assign view to slot. :param view_name: Name of the view to assign. :type view_name: str :param slot: Name of the slot to assign to. Possible values are: left, right, abovecontent, belowcontent, inhead, beforebodyend, edit_inhead :type slot: str :param params: Optionally allows to pass POST parameters to the view. :type params: dict """ event = [e for e in slot_events if e.name == slot] if not event: raise KeyError("Unknown slot '{0}'".format(slot)) objectevent_listeners[(event[0], None)].append( lambda ev: _render_view_on_slot_event(view_name, ev, params))
class RenderLeftSlot(ObjectEvent): name = u'left' class RenderRightSlot(ObjectEvent): name = u'right' class RenderAboveContent(ObjectEvent): name = u'abovecontent' class RenderBelowContent(ObjectEvent): name = u'belowcontent' class RenderInHead(ObjectEvent): name = u'inhead' class RenderBeforeBodyEnd(ObjectEvent): name = u'beforebodyend' class RenderEditInHead(ObjectEvent): name = u'edit_inhead' slot_events = [ RenderLeftSlot, RenderRightSlot, RenderAboveContent, RenderBelowContent, RenderInHead, RenderBeforeBodyEnd, RenderEditInHead, ]