# 20120418¶

## Range 1 ends before it started¶

The server produced a ValueError “Range 1 ends before it started” when lino.apps.pcsw.models.ClientsTest was faced with a contract that ends before it started.

A nice case of a Murphy time bomb. Lino accepted contracts that end before they started. The error message should have come when trying to save the contract.

Solution: New module lino.utils.ranges contains utility methods for working with “ranges”. Most of it was previously in lino.utils at the top-level. But it has one new function lino.utils.ranges.isrange that is now used in the full_clean methods of lino.apps.pcsw.models.Person and lino.apps.isip.models.ContractBase to raise ValidationError( “Coaching period ends before it started.” and “Contracts ends before it started.”.

Even lino.apps.pcsw.fixtures.demo produced invalid ISIP Contracts.

When migrating the customer’s data to the new version, we need to expect and manually handle contracts and persons that fall into this category. See lino.apps.pcsw.migrate.migrate_from_1_4_3().