Deleting¶
Description
Deleting content items in Plone programmatically. How link integrity checks work and how (and when!) to avoid them.
Introduction¶
This document explains how to programmatically delete objects in Plone.
Deleting content by id¶
Deleting content objects is done by IObjectManager.
Example:
# manage_delObjects takes list of ids as an argument
folder.manage_delObjects(["list", "of", "ids", "to", "delete"])
Or:
parent = context.aq_parent
parent.manage_delObjects([context.getId()])
Permissions¶
The user must have Zope 2 Delete objects permission on the content item being
deleted. This is checked in Products.CMFPlone.PloneFolder.manage_delObjects()
.
Otherwise an Unauthorized
exception is raised.
Example how to check for this permission:
from Products.CMFCore import permissions
hospital = self.portal.country.hospital
item = hospital.patient1
mt = getToolByName(self.portal, 'portal_membership')
if mt.checkPermission(permissions.DeleteObjects, item):
# Can delete
raise AssertionError("Oooops. Deletion allowed")
else:
pass
Bypassing permissions¶
This is handy if you work e.g. in a debug shell and you are deleting badly behaved objects:
from AccessControl.SecurityManagement import newSecurityManager
admin = app.acl_users.getUserById("admin")
app.folder_sits.sitsngta.manage_delObjects("examples")
# Try harder:
# app.folder_sits.sitsngta._delObject("examples", suppress_events=True)
import transaction ; transaction.commit()
Deleting all content in a folder¶
This can be a bit tricky. An example:
ids = folder.objectIds() # Plone 3 or older
ids = folder.keys() # Plone 4 or newer
if len(ids) > 0:
# manage_delObject will mutate the list
# so we cannot give it tuple returned by objectIds()
ids = list(ids)
folder.manage_delObjects(ids)
Bypassing link integrity check¶
If link integrity checks has been enabled in the site setup, you cannot delete objects which themselves are link targets or if their children are link targets.
Instead, a LinkIntegrityException
will be raised.
The LinkIntegrityException
contains information identifying
the content which could not be deleted.
The plone.app.linkintegrity.browser.remote
module contains
code which allows you to delete the object in any case.
It catches the exception, modifies the HTTP request
to contain a marker interface allowing delete to happen
and then replays the transaction.
In case the link integrity check fails for manage_delObjects()
,
you will be shown a confirmation dialog. The original request payload
gets pickled and is stored encoded in the HTML form.
When the user presses confirm, the original request gets unpickled
from the HTTP POST
payload. Then the view modifies the Zope publisher
so that it will play the original unpickled HTTP POST
with the marker interface
"Do not care about link integrity breaches" turned on.
Here is an sample batch delete code which tries to work around the link integrity check:
from zope.component import queryUtility
from Products.CMFCore.interfaces import IPropertiesTool
# We need to disable link integrity check,
# because it cannot handle several delete calls in
# one request
ptool = queryUtility(IPropertiesTool)
props = getattr(ptool, 'site_properties', None)
old_check = props.getProperty('enable_link_integrity_checks', False)
props.enable_link_integrity_checks = False
for b in items:
count += 1
obj = b.getObject()
logger.info("Deleting:" + obj.absolute_url() + " " + str(obj.created()))
try:
obj.aq_parent.manage_delObjects([obj.getId()])
except Exception, e:
# E.g. linkintegrityerror or some other
logger.error("Could not remove item:" + obj.absolute_url())
logger.exception(e)
continue
if count % transaction_threshold == 0:
# Prevent transaction becoming too large (memory buffer)
# by committing now and then
logger.info("Committing transaction")
transaction.commit()
props.enable_link_integrity_checks = old_check
logger.info(msg)
Fail safe deleting¶
Sometimes deletion might fail because it dispatches events which might raise exception due to bad broken objects or badly behaving code.
OFS.ObjectManager, the base class for Zope folders, provides an internal method to delete objects from a folder without firing any events:
# Delete object with id "broken-folder" without firing any delete events
site._delObject("broken-folder", suppress_events=True)
The best way to clean up bad objects on your site is via a command line script, in which case remember to commit the transaction after removing the broken objects.
Purging site from old content¶
This term:ZMI script allows you to find content items of certain type and delete them if they are created too long ago:
# Delete FeedfeederItem content items which are more than three months old
from StringIO import StringIO
import DateTime
buf = StringIO()
# DateTime deltas are days as floating points
end = DateTime.DateTime() - 30*3
start = DateTime.DateTime(2000, 1,1)
date_range_query = { 'query':(start,end), 'range': 'min:max'}
items = context.portal_catalog.queryCatalog({
"portal_type":"FeedFeederItem",
"created" : date_range_query,
"sort_on" : "created" })
items = list(items)
print >> buf, "Found %d items to be purged" % len(items)
count = 0
for b in items:
count += 1
obj = b.getObject()
print >> buf, "Deleting:" + obj.absolute_url() + " " + str(obj.created())
obj.aq_parent.manage_delObjects([obj.getId()])
return buf.getvalue()
Below is an advanced version for old item-date-based deletion code
which is suitable for huge sites.
This snippet is from the Products.feedfeeder
package.
It will look for Feedfeeder
items
(automatically generated from RSS) which
are older than X days and delete them.
It's based on Zope 3 page registration (sidenote: I noticed that views do not need to be based on BrowserView page class).
- Transaction thresholds make sure the code runs faster and does not run out of RAM
- Logging to Plone event log files
- Number of days to look into past is not hardcoded
- Manage rights needed to execute the code
You can call this view like:
http://localhost:9999/plonecommunity/@@feed-mega-cleanup?days=90
Here is the view Python source code:
import logging
import transaction
from zope import interface
from zope import component
import DateTime
import zExceptions
logger = logging.getLogger("feedfeeder")
class MegaClean(object):
""" Clean-up old feed items by deleting them on the site.
This is intended to be called from cron weekly.
"""
def __init__(self, context, request):
self.context = context
self.request = request
def clean(self, days, transaction_threshold=100):
""" Perform the clean-up by looking old objects and deleting them.
Commit ZODB transaction for every N objects to that commit buffer does not grow
too long (timewise, memory wise).
@param days: if item has been created before than this many days ago it is deleted
@param transaction_threshold: How often we commit - for every nth item
"""
logger.info("Beginning feed clean up process")
context = self.context.aq_inner
count = 0
# DateTime deltas are days as floating points
end = DateTime.DateTime() - days
start = DateTime.DateTime(2000, 1,1)
date_range_query = {'query':(start,end), 'range': 'min:max'}
items = context.portal_catalog.queryCatalog({
"portal_type": "FeedFeederItem",
"created": date_range_query,
"sort_on": "created" })
items = list(items)
logger.info("Found %d items to be purged" % len(items))
for b in items:
count += 1
obj = b.getObject()
logger.info("Deleting:" + obj.absolute_url() + " " + str(obj.created()))
obj.aq_parent.manage_delObjects([obj.getId()])
if count % transaction_threshold == 0:
# Prevent transaction becoming too large (memory buffer)
# by committing now and then
logger.info("Committing transaction")
transaction.commit()
msg = "Total %d items removed" % count
logger.info(msg)
return msg
def __call__(self):
days = self.request.form.get("days", None)
if not days:
raise zExceptions.InternalError("Bad input. Please give days=60 as HTTP GET query parameter")
days = int(days)
return self.clean(days)
Then we have the view ZCML registration:
<page
name="feed-mega-cleanup"
for="Products.CMFCore.interfaces.ISiteRoot"
permission="cmf.ManagePortal"
class=".feed.MegaClean"
/>