Hi,
I guess you need to write a custom XData service interface for that, where you can do
var
MyCriteria: TCriteria<TMyEntity>;
begin
MyCriteria := Manager.Find<TMyEntity>.Where(Linq.Gt('FieldA', 0));
if AFilter1>0 then
MyCriteria.Add(Linq.Eq('FieldA', AField1));
{...and so on...}
Result := MyCriteria.List;
end;
HTH