Clean up least used catalog keywords

cleanup.py

# -*- coding: utf-8 -*-
from plone import api

import transaction


def get_least_used(limit=1):
    """List all keywords used up to limit times in content."""
    catalog = api.portal.get_tool('portal_catalog')
    keywords = catalog.uniqueValuesFor('Subject')
    least_used = []
    for k in keywords:
        results = catalog(Subject=k)
        if len(results) <= limit:
            least_used.append(k)
    return least_used


def remove_least_used(limit=1):
    """Remove all keywords used up to limit times in content."""
    catalog = api.portal.get_tool('portal_catalog')
    results = catalog()
    least_used = get_least_used(limit)
    n = 0
    for i, b in enumerate(results, 1):
        try:
            obj = b.getObject()
        except (AttributeError, KeyError):
            continue  # skip broken objects
        keywords = list(obj.Subject())
        # remove keywords used up to limit times
        cleanup = [k for k in keywords if k not in least_used]
        if keywords == cleanup:
            continue  # no changes on object
        obj.setSubject(cleanup)
        catalog.catalog_object(obj, idxs=['Subject'], update_metadata=False)
        n += 1
        if n % 1000 == 0:
            transaction.savepoint()
        transaction.commit()