Plone: Notify a user on deleting his account

Question

Using a subscriber on IPrincipalDeletedEvent is not a solution because the user is already deleted and I can't get his email address.

<subscriber
   for="* Products.PluggableAuthService.interfaces.events.IPrincipalDeletedEvent"
   handler="mycontent.userDeleted" />

https://github.com/plone/Products.PlonePAS/blob/4.2/Products/PlonePAS/pas.py#L78

api.user.get(userid=user_id) is None when my userDeleted(user_id, event) is called.

It seems adding a content rule for user removed is working the same.

Any idea how to get user's email address when his account is marked to be deleted? I just want to send him an email: Your account was deleted as you requested.

Answer 1

Monkey patching to add a event just before the user is deleted:

In patches.zcml:

<configure xmlns="http://namespaces.zope.org/zope"
           xmlns:monkey="http://namespaces.plone.org/monkey"
           xmlns:zcml="http://namespaces.zope.org/zcml"
           i18n_domain="myapp">

    <include package="collective.monkeypatcher" />
    <include package="collective.monkeypatcher" file="meta.zcml" />


    <monkey:patch description="Add PrincipalBeforeDeleted event"
                  class="Products.PlonePAS.pas"
                  original="_doDelUser"
                  replacement="mycontent.patches._doDelUser"
                  docstringWarning="true" />
</configure>

In patches.py:

from zope.event import notify
from Products.PluggableAuthService.events import PrincipalDeleted
from Products.PlonePAS.interfaces.plugins import IUserManagement
from Products.PluggableAuthService.PluggableAuthService import \
     _SWALLOWABLE_PLUGIN_EXCEPTIONS
from Products.PluggableAuthService.PluggableAuthService import \
    PluggableAuthService

from Products.PlonePAS.pas import _doDelUser
from Products.PluggableAuthService.interfaces.events import IPASEvent

from zope.interface import implements
from Products.PluggableAuthService.events import PASEvent


class IPrincipalBeforeDeletedEvent(IPASEvent):
    """A user is marked to be removed but still into database.
    """


class PrincipalBeforeDeleted(PASEvent):
    implements(IPrincipalBeforeDeletedEvent)


def _doDelUser(self, id):
    """
    Given a user id, hand off to a deleter plugin if available.
    Fix: Add PrincipalBeforeDeleted notification
    """
    plugins = self._getOb('plugins')
    userdeleters = plugins.listPlugins(IUserManagement)

    if not userdeleters:
        raise NotImplementedError(
            "There is no plugin that can delete users.")

    for userdeleter_id, userdeleter in userdeleters:
        # vvv Custom
        notify(PrincipalBeforeDeleted(id))
        # ^^^ Custom

        try:
            userdeleter.doDeleteUser(id)
        except _SWALLOWABLE_PLUGIN_EXCEPTIONS:
            pass
        else:
            notify(PrincipalDeleted(id))


PluggableAuthService._doDelUser = _doDelUser

Then added a subscriber for this event:

In configure.zcml:

<subscriber
    for="* mycontent.patches.IPrincipalBeforeDeletedEvent"
    handler="mycontent.globalhandlers.userBeforeDeleted" />

In globalhandlers.py:

from Products.CMFCore.utils import getToolByName


def handleEventFail(func):
    def wrapper(*args, **kwargs):
        try:
            func(*args, **kwargs)
        except Exception:
            logger.exception('in {0}'.format(func.__name__))
    return wrapper


@handleEventFail
def userBeforeDeleted(user_id, event):
    """ Notify deleted user about this action. """
    membership_tool = getToolByName(api.portal.get(), 'portal_membership')
    user = membership_tool.getMemberById(user_id)
    email = user.getProperty('email')
    mail_text = """
Hi!
Your account ({0}) was deleted.

Best regards,
Our Best Team""".format(user_id)
    print mail_text
    print email
    # TODO send mail