/// <summary>
/// 拉姆达表达式 or 合并
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="first"></param>
/// <param name="second"></param>
/// <returns></returns>
public static Expression <Func <T, bool> > ExpressionOr <T>(this Expression <Func <T, bool> > first, Expression <Func <T, bool> > second)
{
if (first == null && second == null)
{
return(null);
}
else if (first == null && second != null)
{
return(second);
}
else if (first != null && second == null)
{
return(first);
}
return(first.Combine(second, Expression.Or));
}
