c# - 使用LINQ获取具有属性=另一个对象属性的对象

Question

具有以下伪代码：

    class Foo
    {
        public int id { get; set; }
        public string info { get; set; }
    }

    class Bar
    {
        public int id { get; set; }
        public int FooId { get; set; }
        public string moreInfo { get; set; }
    }

    IList<Foo> foos = new List<Foo>();
    foos.Add(new Foo() { id = 1, info = "first!" });
    foos.Add(new Foo() { id = 2, info = "second!" });
    foos.Add(new Foo() { id = 3, info = "third!" });


    IList<Bar> bars = new List<Bar>();
    bars.Add(new Bar() { id = 1, FooId = 1, moreInfo = "Something" });
    bars.Add(new Bar() { id = 2, FooId = 1, moreInfo = "else" });
    bars.Add(new Bar() { id = 3, FooId = 2, moreInfo = "here" });
    bars.Add(new Bar() { id = 4, FooId = 6, moreInfo = "and" });
    bars.Add(new Bar() { id = 5, FooId = 7, moreInfo = "here as well" });

    var returnValue = select bar from bars
                        where bar.FooId IN foos.Id

我要实现的是一个列表（我的returnValue），其中包含ID为1、2和3的小节，因为它们的FooId在foos列表中。我该怎么办？

Answer 1

var returnValue = bars.Where(b => foos.Select(f => f.Id).Contains(b.FooId);

要么

var returnValue = from b in bars
                  join f in foos on b.FooId equals f.Id
                  select b;