c# - 使用查询表达式对 List 进行排序

Question

我在使用 Linq 订购这样的结构时遇到问题:

public class Person
{
    public int ID { get; set; }
    public List<PersonAttribute> Attributes { get; set; }
}

public class PersonAttribute
{
    public int ID { get; set; }
    public string Name { get; set; }
    public string Value { get; set; }
}

一个人可能会这样:

PersonAttribute Age = new PersonAttribute { ID = 8, Name = "Age", Value = "32" };
PersonAttribute FirstName = new PersonAttribute { ID = 9, Name = "FirstName", Value = "Rebecca" };
PersonAttribute LastName = new PersonAttribute { ID = 10, Name = "LastName", Value = "Johnson" };
PersonAttribute Gender = new PersonAttribute { ID = 11, Name = "Gender", Value = "Female" };

我想使用 LINQ 投影按我选择的人员属性升序对人员列表进行排序，例如，按年龄排序或按名字排序。

我正在尝试类似的东西

string mySortAttribute = "Age"
PersonList.OrderBy(p => p.PersonAttribute.Find(s => s.Name == mySortAttribute).Value);

但是语法让我失望了。有什么线索吗？

Answer 1

OrderBy 是一个生成新序列的 LINQ 扩展。要订购现有序列，您需要添加一两个扩展方法...然后您可以使用:

PersonList.Sort(p => p.Attributes.Find(
  s => s.Name == mySortAttribute).Value);

public static class ListExtensions {
  public static void Sort<TSource, TValue>(
    this List<TSource> source,
    Func<TSource, TValue> selector)
  {
    var comparer = Comparer<TValue>.Default;
    source.Sort((x, y) => comparer.Compare(selector(x), selector(y)));
  }
  public  static void SortDescending<TSource, TValue>(
    this List<TSource> source,
    Func<TSource, TValue> selector)
  {
    var comparer = Comparer<TValue>.Default;
    source.Sort((x, y) => comparer.Compare(selector(y), selector(x)));
  }
}