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

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::

    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

    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.

from urllib.parse import urlencode

from pyramid.exceptions import PredicateMismatch
from pyramid.httpexceptions import HTTPException
from pyramid.httpexceptions import HTTPForbidden
from pyramid.view import render_view

from import ObjectEvent
from import objectevent_listeners

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

def _encode(params):
    if not params:
        return ""
    return urlencode({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.__class__.blank(
        "{}/{}".format(request.path.rstrip("/"), view_name),

    if request.POST:

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

        result = render_view(context, view_request, view_name)
    except (PredicateMismatch, HTTPForbidden):
        return None
    if isinstance(context, HTTPException):
        return None
    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 == slot] if not event: raise KeyError(f"Unknown slot '{slot}'") objectevent_listeners[(event[0], None)].append( lambda ev: _render_view_on_slot_event(view_name, ev, params) )
[docs]class RenderLeftSlot(ObjectEvent): name = "left"
[docs]class RenderRightSlot(ObjectEvent): name = "right"
[docs]class RenderAboveContent(ObjectEvent): name = "abovecontent"
[docs]class RenderBelowContent(ObjectEvent): name = "belowcontent"
[docs]class RenderInHead(ObjectEvent): name = "inhead"
[docs]class RenderBeforeBodyEnd(ObjectEvent): name = "beforebodyend"
[docs]class RenderEditInHead(ObjectEvent): name = "edit_inhead"
slot_events = [ RenderLeftSlot, RenderRightSlot, RenderAboveContent, RenderBelowContent, RenderInHead, RenderBeforeBodyEnd, RenderEditInHead, ]