Nhibernate Criteria进行动态查询并获取行数

Question

我非常需要帮助.

我正在使用Criteria进行动态查询:

ICriteria query = session.CreateCriteria(typeof(Employee));

if (searchOptions.FirstName != null)
{
  query.Add(Expression.Eq("FirstName", searchOptions.FirstName));
}

if (!searchOptions.LastName != null)
{
  query.Add(Expression.Eq("LastName", searchOptions.LastName));
}

if (searchOptions.PhoneNumber != null)
{
  query.CreateCriteria("PhoneNumbers")
    .Add(Expression.Like("Number", searchOptions.PhoneNumber + "%"));
}

在此之后,我需要同时拥有Total Row Count和Pagination.

分页:

query.SetFirstResult(0).SetMaxResults(8);

对于rowcount:

 query.SetProjection(Projections.RowCountInt64());

如何通过使用MultiCriteria或其他方法在单个查询中执行这两个操作.

请帮忙!

Answer 1

你可以在nhibernate 2.0 Efficient Data Paging DataList Control和ObjectDataSource中看到我的答案.

再次编码:

    protected IList<T> GetByCriteria(
        ICriteria criteria, 
        int pageIndex,
        int pageSize, 
        out long totalCount)
    {
        ICriteria recordsCriteria = CriteriaTransformer.Clone(criteria);

        // Paging.
        recordsCriteria.SetFirstResult(pageIndex * pageSize);
        recordsCriteria.SetMaxResults(pageSize);

        // Count criteria.
        ICriteria countCriteria = CriteriaTransformer.TransformToRowCount(criteria);

        // Perform multi criteria to get both results and count in one trip to the database.
        IMultiCriteria multiCriteria = Session.CreateMultiCriteria();
        multiCriteria.Add(recordsCriteria);
        multiCriteria.Add(countCriteria);
        IList multiResult = multiCriteria.List();

        IList untypedRecords = multiResult[0] as IList;
        IList<T> records = new List<T>();
        if (untypedRecords != null)
        {
            foreach (T obj in untypedRecords)
            {
                records.Add(obj);
            }
        }
        else
        {
            records = new List<T>();
        }

        totalCount = Convert.ToInt64(((IList)multiResult[1])[0]);

        return records;
    }

它将原始条件克隆两次:一个返回页面记录的条件和一个总记录计数的条件.它还使用IMultiCriteria在一次往返中执行两个数据库调用.