add the match_http_method predicate (closes #2559932)
This aim at creating views which are selected on other HTTP methods
(PUT, DELETE, ...)
if not rql('CWConstraintType X WHERE X name "RQLUniqueConstraint"',
ask_confirm=False):
rql('INSERT CWConstraintType X: X name "RQLUniqueConstraint"',
ask_confirm=False)