Goals

Produce compact and comprehensive code using NHibernate QueryOver, Restrictions and ICriterion.

Context

We will take an example with an entity Period, defined by a name, a start date and a end date.

Period

Needs

We want to request database to get periods corresponding some criteria :

• all the periods that contains a date
• all the periods that overlap another period

Implementation

We will use PeriodCriteriaBuilder to build the ICriterion blocks :

Some methods build small criteria :

• BuildBeginBeforeOrEqualCriterion(DateTime date)
• BuildEndAfterOrEqualCriterion(DateTime date)
• BuildBeginBetweenCriterion(DateTime start, DateTime end)
• BuildEndBetweenCriterion(DateTime start, DateTime end)

Then we can combine them with logical Restrictions expression to provide more advanced predicates :

• BuildBeginOrEndBetweenCriterion(DateTime start, DateTime end)
• BuildContainsDateCriterion(DateTime date)
• BuildContainsStartOrEndDateCriterion(DateTime start, DateTime end)
• BuildOverlapsPeriodCriterion(DateTime start, DateTime end)

PeriodCriteriaBuilder

QueryOverPeriod

Usage