protected override Expression VisitSelect(DbSelectExpression select)
{
select = base.VisitSelect(select) as DbSelectExpression;
if (select.Skip != null && select.Take != null && select.OrderBy.Count > 0)
{
var skip = select.Skip;
var take = select.Take;
var skipPlusTake = ExpressionEvaluator.Eval(Expression.Add(skip, take));
select = select.SetTake(skipPlusTake).SetSkip(null);
select = select.AddRedundantSelect(this.language, new TableAlias());
select = select.SetTake(take);
select = DbOrderByRewriter.Rewrite(this.language, select) as DbSelectExpression;
var inverted = select.OrderBy.Select(ob => new DbOrderExpression
(
ob.OrderType == OrderType.Ascending ? OrderType.Descending : OrderType.Ascending,
ob.Expression
));
select = select.SetOrderBy(inverted);
select = select.AddRedundantSelect(this.language, new TableAlias());
select = select.SetTake(Expression.Constant(0));
select = DbOrderByRewriter.Rewrite(this.language, select) as DbSelectExpression;
var reverted = select.OrderBy.Select(ob => new DbOrderExpression
(
ob.OrderType == OrderType.Ascending ? OrderType.Descending : OrderType.Ascending,
ob.Expression
));
select = select.SetOrderBy(reverted);
select = select.SetTake(null);
}
return(select);
}
public static DbSelectExpression RemoveOrderExpression(this DbSelectExpression select, DbOrderExpression ordering)
{
if (select.OrderBy != null && select.OrderBy.Count > 0)
{
var orderby = new List <DbOrderExpression>(select.OrderBy);
if (orderby != null)
{
orderby.Remove(ordering);
}
return(select.SetOrderBy(orderby));
}
return(select);
}
public static DbSelectExpression AddOrderExpression(this DbSelectExpression select, DbOrderExpression ordering)
{
var orderby = new List <DbOrderExpression>();
if (select.OrderBy != null)
{
orderby.AddRange(select.OrderBy);
}
if (orderby != null)
{
orderby.Add(ordering);
}
return(select.SetOrderBy(orderby));
}