/// <summary>
/// Finds all topics by the predicate
/// </summary>
/// <param name="predicates">Predicate</param>
/// <returns>Theme collection</returns>
public IEnumerable <BllTheme> GetAllByPredicate(Expression <Func <BllTheme, bool> > predicates)
{
var visitor = new PredicateExpressionVisitor <BllTheme, DalTheme>(Expression.Parameter(typeof(DalTheme), predicates.Parameters[0].Name));
var exp = Expression.Lambda <Func <DalTheme, bool> >(visitor.Visit(predicates.Body), visitor.NewParameter);
return(themeRepository.GetAllByPredicate(exp).Select(theme => theme.ToBllTheme()).ToList());
}