I needed to build a dynamic filter and I wanted to keep using entities. Because of this reason I wanted to use the PredicateBuilder from albahari.

I created the following code:

var invoerDatums = PredicateBuilder.True<OnderzoeksVragen>();
var inner = PredicateBuilder.False<OnderzoeksVragen>();

foreach (var filter in set.RapportInvoerFilter.ToList())
{
    if(filter.IsDate)
    {
        var date = DateTime.Parse(filter.Waarde);
        invoerDatums = invoerDatums.Or(o => o.Van >= date && o.Tot <= date);
    }
    else
    {
        string temp = filter.Waarde;
        inner = inner.Or(o => o.OnderzoekType == temp);
    }
}

invoerDatums = invoerDatums.And(inner);
var onderzoeksVragen = entities.OnderzoeksVragen
                               .AsExpandable()
                               .Where(invoerDatums)
                               .ToList();

When I ran the code there was only 1 filter which wasn't a date filter. So only the inner predicate was filled. When the predicate was executed I got the following error.

The parameter 'f' was not bound in the specified LINQ to Entities query expression.

While searching for an answer I found the following page. But this is already implemented in the LINQKit.

Does anyone else experienced this error and know how to solve it?