PredicateBuilder.New vs PredicateBuilder.True

Question

I am using PredicateBuilder to create a search/filter section in my action. Here it is:

    [HttpPost]
    public ActionResult Test(int? cty, string inumber, int? page)
    {

        var lstValues =
            db.TableName.Include(x => x.Table1)
                .Include(x => x.Table2)
                .Include(x => x.Table3)
                .ToList();

        var predicate = PredicateBuilder.True<TableName>();

        if (!string.IsNullOrWhiteSpace(inumber))
        {
            predicate = predicate.And(x => x.Inumber == inumber);
        }

        if (!string.IsNullOrWhiteSpace(cty.ToString()))
        {
            predicate = predicate.And(x => x.CtyID == cty);
        }

        if (predicate.Parameters.Count > 0)
        {
            lstValues = db.TableName.AsExpandable().Where(predicate).ToList();
            Session["Paging"] = lstValues;
            ViewBag.Paging = lstValues.ToPagedList(page ?? 1, 2);
            return View(lstValues.ToPagedList(page ?? 1, 2));
        }
        else
        {
            return View(lstValues.ToPagedList(page ?? 1, 2));
        }
    }

Under this line PredicateBuilder.True<TableName>(); I get a green squiggly saying

PredicateBuilder.True() is obsolete. Use PredicateBuilder.New instead.

But I have tried PredicateBuilder.New<T> and my predicate always gets a value of 1 even if I don't have any values coming in for the parameters, so cty , and inumber are null. This returns me an empty table.. when it should be returning all records by entering the else statement with return View(lstValues.ToPagedList(page ?? 1, 2)); .

When I use PredicateBuilder.True<T> I get all records returned when all of the parameters are null.

Any idea on why that is? Any help is appreciated.

Answer 1

var predicate = PredicateBuilder.New<TableName>(); is equivalent to Expression<Func<TableName, bool>> predicate = item => false;

What you want instead is PredicateBuilder.New<TableName>(true); to change the default behaviour to include, rather than exclude.