Question

I know how to log the SQL to log4net/NLog/trace window at runtime with the show_sql configuration option.

What I’m looking for is a way to give a Query<T>() to NHibernate retrieve the generated SQL.

I’ve looked through the Persister class, the Drivers, different Interceptors and Events. There are so many places to look, even narrowing down my search would be of great help.

Answer 1

You can get the generated sql queries without execution with the following methods:

For the NHibernate.Linq queries:

public String GetGeneratedSql(System.Linq.IQueryable queryable, ISession session)
{
    var sessionImp = (ISessionImplementor) session;
    var nhLinqExpression = new NhLinqExpression(queryable.Expression, sessionImp.Factory);
    var translatorFactory = new ASTQueryTranslatorFactory();
    var translators = translatorFactory.CreateQueryTranslators(nhLinqExpression, null, false, sessionImp.EnabledFilters, sessionImp.Factory);

    return translators[0].SQLString;
}

For Criteria queries:

public String GetGeneratedSql(ICriteria criteria)
{
    var criteriaImpl = (CriteriaImpl) criteria;
    var sessionImpl = (SessionImpl) criteriaImpl.Session;
    var factory = (SessionFactoryImpl) sessionImpl.SessionFactory;
    var implementors = factory.GetImplementors(criteriaImpl.EntityOrClassName);
    var loader = new CriteriaLoader((IOuterJoinLoadable) factory.GetEntityPersister(implementors[0]), factory, criteriaImpl, implementors[0], sessionImpl.EnabledFilters);

    return loader.SqlString.ToString();
}

For QueryOver queries:

public String GetGeneratedSql(IQueryOver queryOver)
{
    return GetGeneratedSql(queryOver.UnderlyingCriteria);
}

For Hql queries:

public String GetGeneratedSql(IQuery query, ISession session)
{
    var sessionImp = (ISessionImplementor)session;
    var translatorFactory = new ASTQueryTranslatorFactory();
    var translators = translatorFactory.CreateQueryTranslators(query.QueryString, null, false, sessionImp.EnabledFilters, sessionImp.Factory);

    return translators[0].SQLString;
}