Portlet tips (advanced)

Description

How to create and subclass portlets in Plone. How to look-up and modify portlets on the site programmatically.

Creating a portlet

  • You need a paster-compatible product skeleton created using paster create -t plone or paster create -t archetypes commands.
  • Use project specific paster command paster addcontent portlet to create a code skeleton for your new portlet.

Subclassing a portlet

You can subclass a portlet to create a new portlet type with your enhanced functionality.

Using z3c.form in portlets

z3c.form is a modern form library for Plone. The out of the box Plone portlets use older zope.formlib.

Discussion related to the matter

Overriding portlet rendering

Use <plone:portletRenderer> directive. Specify 1) layer, 2) template and/or 3) class 4) portlet interface.

You need <include package=""> directive for the package whose portlet you are going to override. 

<configure
    xmlns:plone="http://namespaces.plone.org/plone"
    >

        <include package="plone.app.portlets" />

        <plone:portletRenderer
           portlet="plone.app.portlets.portlets.news.INewsPortlet"
           template="mytheme_news.pt"
           layer=".interfaces.IThemeSpecific"
           />

</configure>

More information

available property

The portlet renderer can define available property to hint the portlet manager when the portlet should be rendered.

Example

class Renderer(base.Renderer):

    @property
    def available(self):
        # Show this portlet for logged in users only
        return not self.anonymous

Iterate portlets assigned to the portal root

Below is an simple example how to print all portlets which have been assigned to the portal root: 

def check_root_portlets(self):
    """ Print all portlet assignments in the portal root """

    from zope.component import getUtility, getMultiAdapter
    from plone.portlets.interfaces import IPortletManager
    from plone.portlets.interfaces import IPortletAssignment
    from plone.portlets.interfaces import IPortletAssignmentMapping

    content = self.portal

    for manager_name in [ "plone.leftcolumn", "plone.rightcolumn" ]:

        print "Checking portlet column:" + manager_name

        manager = getUtility(IPortletManager, name=manager_name, context=content)

        mapping = getMultiAdapter((content, manager), IPortletAssignmentMapping)

        # id is portlet assignment id
        # and automatically generated
        for id, assignment in mapping.items():
            print "Found portlet assignment:" + id + " " + str(assignment)

Looking up a portlet by id

Here are some tips how to extract the portlet id data in the portlet renderer to pass around to be consumed elsewhere.

portlets.py:

class Renderer(base.Renderer):

    def getImageURL(self, imageDesc):
        """
        :return: The URL where the image can be downloaded from.

        """
        context = self.context.aq_inner

        # [{'category': 'context', 'assignment': <imageportlet.portlets.Assignment object at 0x1138bb140>, 'name': u'bound-method-assignment-title-of-assignment-at-1', 'key': '/Plone/fi'},
        params = dict(
            portletName=self.__portlet_metadata__["name"],
            portletManager=self.__portlet_metadata__["manager"],
            image=imageDesc["id"],
            modified=self.data._p_mtime,
            portletKey=self.__portlet_metadata__["key"],
        )

        imageURL = "%s/@@image-portlet-downloader?%s" % (context.absolute_url(), urllib.urlencode(params))

        return imageURL

Then we can re-look-up this portlet and its image field, based on the field name, in the downloader view: 

# Zope imports
from zExceptions import InternalError
from zope.interface import Interface
from zope.component import getUtility, getMultiAdapter
from five import grok

# Plone imports
from plone.portlets.interfaces import IPortletManager
from plone.portlets.interfaces import IPortletRetriever
from plone.namedfile.utils import set_headers, stream_data


# Local imports
from interfaces import IAddonSpecific

grok.templatedir("templates")
grok.layer(IAddonSpecific)


class ImagePortletHelper(grok.CodeView):
    """
    Expose stuff downloadable from the image portlet BLOBs.
    """
    grok.context(Interface)
    grok.baseclass()


class ImagePortletImageDownload(ImagePortletHelper):
    """
    Expose image fields as downloadable BLOBS from the image portlet.

    Allow set caching rules (content caching for this view)
    """
    grok.context(Interface)
    grok.name("image-portlet-downloader")

    def getPortletById(self, content, portletManager, key, name):
        """
        :param content: Context item where the look-up is performed

        :param portletManager: Portlet manager name as a string

        :param key: Assignment key... context path as string for content portlets

        :param name: Portlet name as a string

        :return: Portlet assignment instance
        """

        # Make sure we got input
        assert key, "Give a proper portlet assignment key"
        assert name, "Give a proper portlet assignment name"

        # Resolve portlet and its image field
        manager = getUtility(IPortletManager, name=portletManager, context=content)

        # Mappings can be directly used only when
        # portlet is directly assignment to the content.
        # If it is assigned to the parent we would fail here.
        # mapping = getMultiAdapter((content, manager), IPortletAssignmentMapping)

        retriever = getMultiAdapter((content, manager,), IPortletRetriever)

        for assignment in retriever.getPortlets():
            if assignment["key"] == key and assignment["name"] == name:
                return assignment["assignment"]

        return None

    def render(self):
        """

        """
        content = self.context.aq_inner

        # Read portlet assignment pointers from the GET query
        name = self.request.form.get("portletName")
        manager = self.request.form.get("portletManager")
        imageId = self.request.form.get("image")
        key = self.request.form.get("portletKey")

        portlet = self.getPortletById(content, manager, key, name)
        if not portlet:
            raise InternalError("Portlet not found: %s %s" % (key, name))

        image = getattr(portlet, imageId, None)
        if not image:
            # Ohops?
            raise InternalError("Image was empty: %s" % imageId)

See imageportlet add-on for the complete example.

Walking through every portlet on the site

The following code iterates through all portlets assigned directly to content items. This excludes dashboard, group and content type based portlets. Then it prints some info about them and renders them.

Example code:

from Products.Five.browser import BrowserView

from zope.component import getUtility, getMultiAdapter
from zope.app.component.hooks import setHooks, setSite, getSite

from plone.portlets.interfaces import IPortletType
from plone.portlets.interfaces import IPortletManager
from plone.portlets.interfaces import IPortletAssignment
from plone.portlets.interfaces import IPortletDataProvider
from plone.portlets.interfaces import IPortletRenderer
from plone.portlets.interfaces import IPortletAssignmentMapping
from plone.portlets.interfaces import ILocalPortletAssignable

from Products.CMFCore.interfaces import IContentish

class FixPortlets(BrowserView):
        """ Magical portlet debugging view """

        def __call__(self):
            """
            """

            request = self.request

            portal = getSite()

            # Not sure why this is needed...
            view = portal.restrictedTraverse('@@plone')

            # Query all content items on the site which can get portlets assigned
            # Note that this should excule special, hidden, items like tools which otherwise
            # might appearn in portal_catalog queries
            all_content = portal.portal_catalog(show_inactive=True, language="ALL", object_provides=ILocalPortletAssignable.__identifier__)

            # Load the real object instead of index stub
            all_content = [ content.getObject() for content in all_content ]

            # portal itself does not show up in the query above,
            # though it might contain portlet assignments
            all_content = list(all_content) + [portal]

            for content in all_content:

                    for manager_name in [ "plone.leftcolumn", "plone.rightcolumn" ]:

                            manager = getUtility(IPortletManager, name=manager_name, context=content)

                            mapping = getMultiAdapter((content, manager), IPortletAssignmentMapping)

                            # id is portlet assignment id
                            # and automatically generated
                            for id, assignment in mapping.items():
                                    print "Found portlet assignment:" + id + " " + str(assignment)

                                    renderer = getMultiAdapter((content, request, view, manager, assignment), IPortletRenderer)

                                    # Renderer acquisition chain must be set-up so that templates
                                    # et. al. can resolve permission inheritance
                                    renderer = renderer.__of__(content)

                                    # Seee http://svn.zope.org/zope.contentprovider/trunk/src/zope/contentprovider/interfaces.py?rev=98212&view=auto
                                    renderer.update()
                                    html = renderer.render()
                                    print "Got HTML output:" + html


            return "OK"

For more information about portlet assignments and managers, see

Checking if a certain context portlet is active on a page

  • Iterate through portlet managers by name
  • Get portlet retriever for the manager
  • Get portlets
  • Check if the portlet assignment provides your particular portlet marker interface

Example:

import Acquisition
from zope.component import getUtility, getMultiAdapter


from plone.portlets.interfaces import IPortletRetriever, IPortletManager

for column in ["plone.leftcolumn", "plone.rightcolumn"]:

    manager = getUtility(IPortletManager, name=column)

    retriever = getMultiAdapter((self.context, manager), IPortletRetriever)

    portlets = retriever.getPortlets()

    for portlet in portlets:

        # portlet is {'category': 'context', 'assignment': <FacebookLikeBoxAssignment at facebook-like-box>, 'name': u'facebook-like-box', 'key': '/isleofback/sisalto/huvit-ja-harrasteet
        # Identify portlet by interface provided by assignment
        if IFacebookLikeBoxData.providedBy(portlet["assignment"]):
            return True

return False

Rendering a portlet

Below is an example how to render a portlet in Plone

  • A portlet is assigned to some context in some portlet manager
  • We can dig these assignments up by portlet id (not user visible) or portlet type (portlet assignment interface)

How to get your portlet HTML:

import Acquisition
from zope.component import getUtility, getMultiAdapter, queryMultiAdapter
from plone.portlets.interfaces import IPortletRetriever, IPortletManager, IPortletRenderer

def get_portlet_manager(column):
    """ Return one of default Plone portlet managers.

    @param column: "plone.leftcolumn" or "plone.rightcolumn"

    @return: plone.portlets.interfaces.IPortletManagerRenderer instance
    """
    manager = getUtility(IPortletManager, name=column)
    return manager

def render_portlet(context, request, view, manager, interface):
    """ Render a portlet defined in external location.

    .. note ::

        Portlets can be idenfied by id (not user visible)
        or interface (portlet class). This method supports look up
        by interface and will return the first matching portlet with this interface.

    @param context: Content item reference where portlet appear

    @param manager: IPortletManagerRenderer instance

    @param view: Current view or None if not available

    @param interface: Marker interface class we use to identify the portlet. E.g. IFacebookPortlet

    @return: Rendered portlet HTML as a string, or empty string if portlet not found
    """

    retriever = getMultiAdapter((context, manager), IPortletRetriever)

    portlets = retriever.getPortlets()

    assignment = None

    for portlet in portlets:

        # portlet is {'category': 'context', 'assignment': <FacebookLikeBoxAssignment at facebook-like-box>, 'name': u'facebook-like-box', 'key': '/isleofback/sisalto/huvit-ja-harrasteet
        # Identify portlet by interface provided by assignment
        if interface.providedBy(portlet["assignment"]):
            assignment = portlet["assignment"]
            break

    if assignment is None:
        # Did not find a portlet
        return ""

    #- A special type of content provider, IPortletRenderer, knows how to render each
    #type of portlet. The IPortletRenderer should be a multi-adapter from
    #(context, request, view, portlet manager, data provider).

    renderer = queryMultiAdapter((context, request, view, manager, assignment), IPortletRenderer)

    # Make sure we have working acquisition chain
    renderer = renderer.__of__(context)

    if renderer is None:
        raise RuntimeError("No portlet renderer found for portlet assignment:" + str(assignment))

    renderer.update()
    # Does not check visibility here... force render always
    html = renderer.render()

    return html

How to use this code in your own view:

def render_slope_info(self):
    """ Render a portlet from another page in-line to this page

    Does not render other portlets in the same portlet manager.
    """
    context = self.context.aq_inner
    request = self.request
    view = self

    column = "isleofback.app.frontpageportlets"

    # Alternatively, you can directly query your custom portlet manager by interface
    from isleofback.app.portlets.slopeinfo import ISlopeInfo

    manager = get_portlet_manager(column)

    html = render_portlet(context, request, view, manager, ISlopeInfo)
    return html

How to call view helper function from page template

<div tal:replace="structure view/render_slope_info" />

More info

Hiding unwanted portlets

Example portlets.xml:

<!-- This leaves only News portlet -->

<portlet addview="portlets.Calendar" remove="true" />
<portlet addview="portlets.Classic" remove="true" />
<portlet addview="portlets.Login" remove="true" />
<portlet addview="portlets.Events" remove="true" />
<portlet addview="portlets.Recent" remove="true" />
<portlet addview="portlets.rss" remove="true" />
<portlet addview="portlets.Search" remove="true" />
<portlet addview="portlets.Language" remove="true" />
<portlet addview="plone.portlet.collection.Collection" remove="true" />
<portlet addview="plone.portlet.static.Static" remove="true" />

<!-- collective.flowplayer add-on -->
<portlet addview="collective.flowplayer.Player" remove="true" />

Portlet na,es can be found in plone.app.portlets/configure.zcml.

More info:

Disabling right or left columns in a view or template

Sometimes, when you work with custom views and custom templates you need to disable right or left column for portlets.

This is how you do from within a template:

<metal:override fill-slot="top_slot"
    tal:define="disable_column_one python:request.set('disable_plone.leftcolumn',1);
                disable_column_two python:request.set('disable_plone.rightcolumn',1);"/>

And this is how you do it from within a view:

import grok

class SomeView(grok.View):
    grok.context(IPloneSiteRoot)

    def update(self):
        super(SomeView, self).update()
        self.request.set('disable_plone.rightcolumn',1)
        self.request.set('disable_plone.leftcolumn',1)

Source: http://stackoverflow.com/questions/5872306/how-can-i-remove-portlets-in-edit-mode-with-plone-4

Disabling right or left columns on a context

Sometimes you just want to turn off the portlets in a certain context that doesn't have a template or fancy view. To do this in code do this: 

from zope.component import getMultiAdapter
from zope.component import getUtility

from plone.portlets.interfaces import IPortletManager
from plone.portlets.interfaces import ILocalPortletAssignmentManager
from plone.portlets.constants import CONTEXT_CATEGORY

# Get the proper portlet manager
manager = getUtility(IPortletManager, name=u"plone.leftcolumn")

# Get the current blacklist for the location
blacklist = getMultiAdapter((context, manager), ILocalPortletAssignmentManager)

# Turn off the manager
blacklist.setBlacklistStatus(CONTEXT_CATEGORY, True)

Or just do it using GenericSetup like a sane person:

Creating a new portlet manager

If you need additional portlet slots at the site. In this example we use Products.ContentWellCode to provide us some facilities as a dependency.

  • Create a viewlet which will handle portlet rendering in a normal page mode. Have several portlet slots, a.k.a. wells, where you can drop in portlets. Wells are rendered horizontally side-by-side and portlets going in from top to bottom.
  • Register this viewlet in a viewlet manager where you wish to show your portlets on the main template
  • Have a management view which allows you to shuffle portlets around. This is borrowed from Products.ContentWellPortlets.
  • Register portlet wells in portlets.xml - note that one management view can handle several slots as in the example below

The code skeleton works against this Plone add-on template.

Example portlet manager viewlets.py:

"""

    For more information see

    * http://collective-docs.readthedocs.org/en/latest/views/viewlets.html

"""

import logging
from fractions import Fraction

# Zope imports
from zope.interface import Interface
from zope.component import getMultiAdapter, getUtility, queryUtility
from five import grok

# Plone imports
from plone.portlets.interfaces import IPortletManager
from plone.app.layout.viewlets.interfaces import IPortalFooter
from Products.CMFCore.utils import getToolByName

# Local imports
from interfaces import IAddonSpecific, IThemeSpecific

grok.templatedir("templates")
grok.layer(IThemeSpecific)

# By default, set context to zope.interface.Interface
# which matches all the content items.
# You can register viewlets to be content item type specific
# by overriding grok.context() on class body level
grok.context(Interface)

logger = logging.getLogger("PortletManager")


class CustomPortletViewlet(grok.Viewlet):
    """ grok viewlet base class for a custom portlet renderer based on Products.ContentWellPortlets

    Orignal code from Products.ContentWellPortlets
    """
    grok.baseclass()

    # Id which we use to store portlets
    name = ""

    # Name of browser view which will render the management interface for portlets
    # in this manager
    manage_view = ""

    # We have 5 portlet slots in this viewlet
    portlet_count = 5

    def update(self):
        context_state = getMultiAdapter((self.context, self.request), name=u'plone_context_state')
        self.manageUrl =  '%s/%s' % (context_state.view_url(), self.manage_view)

        ## This is the way it's done in plone.app.portlets.manager, so we'll do the same
        mt = getToolByName(self.context, 'portal_membership')
        self.canManagePortlets = mt.checkPermission('Portlets: Manage portlets', self.context)

    def showPortlets(self):
        return '@@manage-portlets' not in self.request.get('URL')

    def portletManagersToShow(self):
        visibleManagers = []

        for n in range(1,self.portlet_count):
            name = '%s%s' % (self.name, n)

            try:
                mgr = getUtility(IPortletManager, name=name, context=self.context)
            except:
                # In the case we have problems to load portlet manager, do something about it
                # This is graceful fallback in a situation where 1) add-on is already installed
                # 2) new portlet code drops in and re-run add-on installer is
                continue

            if mgr(self.context, self.request, self).visible:
                visibleManagers.append(name)

        import pdb ; pdb.set_trace()

        managers = []
        numManagers = len(visibleManagers)
        for counter, name in enumerate(visibleManagers):
            pos = 'position-%s' % str(Fraction(counter, numManagers)).replace('/',':')
            width = 'width-%s' % (str(Fraction(1, numManagers)).replace('/',':') if numManagers >1 else 'full')
            managers.append((name, 'cell %s %s %s' % (name.split('.')[-1], width, pos)))
        return managers


class ColophonPortlets(CustomPortletViewlet):
    """
    Render a new series of portlets in colophon.
    """

    # This name is used to store portlets,
    # as referred in portlets.xml
    name = 'PortletsColophon'

    # This is custom management URL view for this,
    # registered thru ZCML to point to Products.ContentWellContent manager view class.
    manage_view = '@@manage-portlets-colophon'

    grok.viewletmanager(IPortalFooter)
    grok.template("portlets-colophon")

# Define a portlet manager declaration
from Products.ContentWellPortlets.browser.interfaces import IContentWellPortletManager

class IColphonPortlets(IContentWellPortletManager):
     """
     This viewlet is a place holder to match portlets.xml and portlet management view together.

     * Manager is referred by name in manage page template

     * portlets.xml refers to this interface

     * provider:ColophonPortlets expression is also used in template to render the actual porlets
     """

Example ZCML bit

<!-- Register new portlet management view for our portlet manager -->


<include package ="plone.app.portlets" />

<!--

    The .pt file is customized for the portlet manager name (from portlets.xml)
    and management link.

  -->
<browser:page
   name="manage-portlets-colophon"
   for="plone.portlets.interfaces.ILocalPortletAssignable"
   class="plone.app.portlets.browser.manage.ManageContextualPortlets"
   template="templates/manage-portlets-colophon.pt"
   permission="plone.app.portlets.ManagePortlets"
/>

The page template for the manager manage-portlets-colophon.pt is the following 

<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:metal="http://xml.zope.org/namespaces/metal"
      xmlns:tal="http://xml.zope.org/namespaces/tal"
      xmlns:i18n="http://xml.zope.org/namespaces/i18n"
      metal:use-macro="context/main_template/macros/master"
      >

    <head>
        <div metal:fill-slot="javascript_head_slot" tal:omit-tag="">
            <link type="text/css" rel="kinetic-stylesheet"
                tal:attributes="href string:${context/absolute_url}/++resource++manage-portlets.kss"/>
        </div>
    </head>
    <body class="manage-portlet-well">

        <metal:block fill-slot="top_slot"
                         tal:define="disable_column_one python:request.set('disable_plone.leftcolumn',1);
                                     disable_column_two python:request.set('disable_plone.rightcolumn',1);" />

        <div metal:fill-slot="main">

            <tal:warning tal:condition="plone_view/isDefaultPageInFolder">
                <dl class="portalMessage warning">
                    <dt i18n:translate="message_warning_above_content_area_dt">Is this really where you want to add portlets above the content?</dt>
                    <dd i18n:translate="message_warning_above_content_area_dd">If you add portlets here, they will only appear on this item. If instead you want portlets to appear on all items in this folder,
                        <a href=""
                           tal:attributes="href string:${plone_view/getCurrentFolderUrl}/@@manage-portlets-colophon"
                           i18n:name="manage-portletsinheader_link">
                            <span i18n:translate="add_them_to_the_folder_itself">add them to the folder itself</span>
                        </a>
                    </dd>
                <dl>
            </tal:warning>

            <h1 class="documentFirstHeading"
                i18n:translate="manage_portlets_in_header">Manage portlets in colophon
            </h1>

            <p>
                 <a href=""
                       class="link-parent"
                       tal:attributes="href string:${context/absolute_url}"
                       i18n:translate="return_to_view">
                    Return
                 </a>
            </p>

            <div class="porlet-well_manager">
                <h2 i18n:translate="portlet-well-a">Colophon Portlet Well 1</h2>
                <span tal:replace="structure provider:PortletsColophon1" />
            </div>

            <div class="porlet-well_manager">
                <h2 i18n:translate="portlet-well-a">Colophon Portlet Well 2</h2>
                <span tal:replace="structure provider:PortletsColophon2" />
            </div>

            <div class="porlet-well_manager">
                <h2 i18n:translate="portlet-well-a">Colophon Portlet Well 3</h2>
                <span tal:replace="structure provider:PortletsColophon3" />
            </div>

            <div class="porlet-well_manager">
                <h2 i18n:translate="portlet-well-a">Colophon Portlet Well 4</h2>
                <span tal:replace="structure provider:PortletsColophon4" />
            </div>

            <div class="porlet-well_manager">
                <h2 i18n:translate="portlet-well-a">Colophon Portlet Well 5</h2>
                <span tal:replace="structure provider:PortletsColophon5" />
            </div>


        </div>

    </body>
</html>

Then we have portlets-colophon.pt page template for the viewlet which renders the portlets and related management link 

<div id="portlets-colophon"
     class="row">

    <tal:block tal:condition="viewlet/showPortlets">
        <tal:portletmanagers tal:repeat="manager viewlet/portletManagersToShow">
            <div tal:attributes="class python:manager[1]"
                 tal:define="mgr python:manager[0]"
                 tal:content="structure provider:${mgr}" />

        </tal:portletmanagers>

        <div style="clear:both"><!-- --></div>

        <div class="manage-portlets-link"
           tal:condition="viewlet/canManagePortlets">
            <a href=""
               class="managePortletsFallback"
               tal:attributes="href viewlet/manageUrl">
               Add, edit or remove a portlet in <b tal:content="viewlet/name" />
            </a>
        </div>

    </tal:block>

</div>

Finally there is portlets.xml which lists all the portlet managers and associates them with the used interface 

<?xml version="1.0"?>
<!-- Set up all the new portlet managers we need above and below the content well -->
<portlets>


    <portletmanager
         name="PortletsColophon1"
         type="youraddon.viewlets.IColphonPortlets"
    />

    <portletmanager
         name="PortletsColophon2"
         type="youraddon.viewlets.IColphonPortlets"
    />

    <portletmanager
         name="PortletsColophon3"
         type="youraddon.viewlets.IColphonPortlets"
    />

    <portletmanager
         name="PortletsColophon4"
         type="youraddon.viewlets.IColphonPortlets"
    />

    <portletmanager
         name="PortletsColophon5"
         type="youraddon.viewlets.IColphonPortlets"
    />

</portlets>

More info

Fixing relative links for static text portlets

Note

This should be no longer issue with Plone 4.1 and TinyMCE 1.3+ when using UID links.

Example how to convert links in all static text portlets: 

from lxml import etree
from StringIO import StringIO
import urlparse
from lxml import html

def fix_links(content, absolute_prefix):
    """
    Rewrite relative links to be absolute links based on certain URL.

    @param html: HTML snippet as a string
    """

    parser = etree.HTMLParser()

    content = content.strip()

    tree  = html.fragment_fromstring(content, create_parent=True)

    def join(base, url):
        """
        Join relative URL
        """
        if not (url.startswith("/") or "://" in url):
            return urlparse.urljoin(base, url)
        else:
            # Already absolute
            return url

    for node in tree.xpath('//*[@src]'):
        url = node.get('src')
        url = join(absolute_prefix, url)
        node.set('src', url)
    for node in tree.xpath('//*[@href]'):
        href = node.get('href')
        url = join(absolute_prefix, href)
        node.set('href', url)

    data =  etree.tostring(tree, pretty_print=False, encoding="utf-8")

    return data