Select 使用查询表达式的常量值

Select const value using query expression

如何通过查询表达式或方法表达式实现这个查询:

Select 1, a.Id 
From a
Where a.code = x

像这样:

var data = a.Where(a => a.code == x).Select(a => new { Constant = 1, a.Id });