linq - 加入集合的 LINQ 更新

Question

如何使用 LINQ 从第二个列表中的对象更新一个列表中的对象？我的问题与加入期间的 LINQ 行内属性更新非常相似，只是在我的情况下，第二个列表小于父列表。换句话说，我想更新那些在第二个集合中具有相应更新的主集合成员。否则我希望主对象保持不变。上面引用的文章中的技术似乎导致了两个集合的内部连接。

谢谢

Answer 1

另一篇文章中的答案也适合您的问题，因为您真正想要的是内部连接。需要注意的是，内连接仅用于执行功能，而不是修改列表（即不满足内连接的项目在列表中保持不变）。

为了完整起见，这是我将使用的解决方案：

List<Person> people = new List<Person>();
people.Add( new Person{ Name = "Timothy", Rating = 2 } );
people.Add( new Person{ Name = "Joe", Rating = 3 } );
people.Add( new Person{ Name = "Dave", Rating = 4 } );

List<Person> updatedPeople = new List<Person>();
updatedPeople.Add( new Person { Name = "Timothy", Rating = 1 } );
updatedPeople.Add( new Person { Name = "Dave", Rating = 2 } );

ShowPeople( "Full list (before changes)", people );

Func<Person, Person, Person> updateRating =
    ( personToUpdate, personWithChanges ) =>
    {
        personToUpdate.Rating = personWithChanges.Rating;
        return personToUpdate;
    };
var updates = from p in people
              join up in updatedPeople
                  on p.Name equals up.Name
              select updateRating( p, up );

var appliedChanges = updates.ToList();

ShowPeople( "Full list (after changes)", people );
ShowPeople( "People that were edited", updatedPeople );
ShowPeople( "Changes applied", appliedChanges );

这是我得到的输出：

Full list (before changes)
-----
Name: Timothy, Rating: 2
Name: Joe, Rating: 3
Name: Dave, Rating: 4

Full list (after changes)
-----
Name: Timothy, Rating: 1
Name: Joe, Rating: 3
Name: Dave, Rating: 2

People that were edited
-----
Name: Timothy, Rating: 1
Name: Dave, Rating: 2

Changes applied
-----
Name: Timothy, Rating: 1
Name: Dave, Rating: 2