FIXES FRMW-2878 **What** Currently, the `one-to-one` unique constraints does not account for deleted record. This prevents from inserting a new record wth the same fk if another one is deleted. **Caveat** `hasOne` with FK option is meant to be a special case, for example a many to one - one to many without defining the other side of the relation. In that case we don't handle this behaviour and keep it as it is
Cart Module
A Cart is a collection of items that a customer intends to purchase. The Cart also stores where the items should be shipped, how they should be shipped, how the goods will be paid for and who the customer is. The Cart facilitates calculations of totals and validation of purchase flows.