PredicateBuilder.New vs PredicateBuilder.True

Question

I use PredicateBuilder to create a search / filter section in my action. Here he 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 is PredicateBuilder.True<TableName>(); i get an evil expression

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

But I tried PredicateBuilder.New<T> , and my predicate always gets the value 1 , even if I have no values ​​for the parameters, so cty and inumber are zero. This returns me an empty table .. when it should return all records by entering the else with return View(lstValues.ToPagedList(page ?? 1, 2)); .

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

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

Answer 1

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

Instead, you need PredicateBuilder.New<TableName>(true); change the default behavior, not exclude.