[migration] hackish black magic to bootstrap addition of formula attr during migration Turns out we can't add an attribute to CWAttribute before the attribute exists. add_attribute generates rql with a 'formula' relation, which CW doesn't know about yet, so things get unhappy. Once that is fixed, we need to make the CWAttribute addition operation deal with CWAttribute entities that don't have a formula yet. Finally, move the migration to bootstrapmigration_repository so it happens early on, and use add_entity_type rather than add_relation_type for CWComputedRType.

try:
    rtype, = __args__
except ValueError:
    print 'USAGE: cubicweb-ctl shell <instance> detect_cycle.py -- <relation type>'
    print

graph = {}
for fromeid, toeid in rql('Any X,Y WHERE X %s Y' % rtype):
    graph.setdefault(fromeid, []).append(toeid)

from logilab.common.graph import get_cycles

for cycle in get_cycles(graph):
    print 'cycle', '->'.join(str(n) for n in cycle)