NHibernate IQueryOver.ToRowCountQuery() equivalent when Using HQL IQuery

问题

I'm trying to implement paging within my project.

When using NHibernate's IQueryOver syntax as shown below things are working as expected.

    public PagedResult<T> ExecutePagedQuery(IQueryOver<T,T> query)
    {
        SetPaging(query);

        var results = query.Future<T>();
        var count = query.ToRowCountQuery().FutureValue<int>();

        return new PagedResult<T>()
        {
            TotalItemCount = count.Value,
            PageOfResults = results.ToList()
        };
    }

    protected virtual void SetPaging(IQueryOver<T, T> query)
    {
        var maxResults = PageSize;
        var numberToSkip = (PageNumber - 1) * PageSize;

        query.Skip(numberToSkip).Take(maxResults);
    }

For some queries we are using HQL instead of the IQueryOver syntax however.

I'm wondering if there is an equivalent to "query.ToRowCountQuery().FutureValue< int >()" that can be used when querying when passing an IQuery insead of an IQueryOver to provide the row count.

    public PagedResult<T> ExecutePagedQuery(IQuery query)
    {
        SetPaging(query);

        var results = query.Future<T>();
        var count = // ToRowCountQueryEquivalent?

        return new PagedResult<T>()
        {
            TotalItemCount = count,
            PageOfResults = results.ToList()
        };
    }

    protected virtual void SetPaging(IQuery query)
    {
        var maxResults = PageSize;
        var numberToSkip = (PageNumber - 1) * PageSize;

        query.SetFirstResult(numberToSkip);
        query.SetMaxResults(maxResults);
    }

回答1:

some crazy idea

string countQuery;
if (query.QueryString.StartsWith("SELECT", StringComparison.OrdinalIgnoreCase))
    countQuery = Regex.Replace(query.QueryString, "SELECT (.*) FROM", @"SELECT Count($1) FROM", RegexOptions.IgnoreCase);
else
    countQuery = "SELECT COUNT(*) " + query.QueryString;

回答2:

We've since converted our HQL queries to IQueryOver allowing us to take advantage of the ToRowCountQuery() helper.

来源：https://stackoverflow.com/questions/7733965/nhibernate-iqueryover-torowcountquery-equivalent-when-using-hql-iquery

标签

nhibernate

hql

paging