/// <summary>
/// Remove all not requested fields from SQL query
/// </summary>
/// <typeparam name="TResult">Type of projection type</typeparam>
/// <param name="query">NHibernate query</param>
/// <param name="keepMembers">List of members to select</param>
/// <returns>Optimized NHibernate query</returns>
public static IQueryable <TResult> OptimizeQuery <TResult>(this IQueryable <TResult> query, IReadOnlyCollection <MemberInfo> keepMembers)
{
if (query == null)
{
throw new ArgumentNullException(nameof(query));
}
if (keepMembers == null)
{
throw new ArgumentNullException(nameof(keepMembers));
}
if (keepMembers.Count == 0)
{
throw new ArgumentException("Member list should containes at last one field", nameof(keepMembers));
}
var fieldRemover = new MemberRemoverVisitor(keepMembers, query.Expression);
if (fieldRemover.UnusedMembers.Count > 0)
{
throw new ArgumentException("Member list contents unexiting in members the query. Check passed memebers.");
}
return(query.Provider.CreateQuery <TResult>(fieldRemover.ClearedExpression));
}
/// <summary>
/// Remove all not requested fields from select clause
/// </summary>
/// <typeparam name="TDbObject">Type of database mapped object</typeparam>
/// <typeparam name="TResult">Type of projection</typeparam>
/// <param name="select">Expression with select clause</param>
/// <param name="keepMembers">List of members to select</param>
/// <returns>Optimized NHibernate query</returns>
public static Expression <Func <TDbObject, TResult> > OptimizeSelect <TDbObject, TResult>(
this Expression <Func <TDbObject, TResult> > select,
IReadOnlyCollection <MemberInfo> keepMembers)
{
if (select == null)
{
throw new ArgumentNullException(nameof(select));
}
if (keepMembers == null)
{
throw new ArgumentNullException(nameof(keepMembers));
}
if (keepMembers.Count == 0)
{
throw new ArgumentException("Selected member list should containes at last one field", nameof(keepMembers));
}
var fieldRemover = new MemberRemoverVisitor(keepMembers, select);
if (fieldRemover.UnusedMembers.Count > 0)
{
throw new ArgumentException("Member list contents unexiting in members the query. Check passed memebers.");
}
return((Expression <Func <TDbObject, TResult> >)fieldRemover.ClearedExpression);
}
