c# - 匿名委托(delegate) - 使用对象集合搜索属性

Question

以下是我的应用程序中使用匿名委托(delegate)搜索属性集合的当前代码:

public class MyObject
{
    public MyObject() { }

    public string MyObjectId { get; set; }
    public List<MySubObject> SubObjects { get; set; }
}

public class MySubObject
{
    public MySubObject() { }

    public string MySubObjectId { get; set; }
}

public List<MyObject> Search(string input)
{
    List<MyObject> AllObjects = Data.GetAllObjects();
    List<MyObject> SearchResults = new List<MyObject>();

    SearchResults = AllObjects.FindAll
    (
        delegate(MyObject o)
        {
            return e.MyObjectId.Equals(input)
        }
    );

    if (SearchResults .Count.Equals(0))
            SearchResults = null;

        return SearchResults ;
}

我想修改匿名委托(delegate)以通过通用列表中的 MySubObject.MySubObjectId 属性而不是 MyObjectId 属性进行搜索。我如何修改匿名委托(delegate)中的代码来完成此任务？

Answer 1

尝试以下操作

delegate(MyObject o) {
  var mySubObject = o as MySubObject;
  return mySubObject != null && mySubObject.MySubObjectId == input;
}

请注意，您还可以在此处使用更短的 lambda 语法

(o) => {
  var mySubObject = o as MySubObject;
  return mySubObject != null && mySubObject.MySubObjectId == input;
}

或者 LINQ 查询

var searchResult = AllObjects
  .OfType<MySubObject>()
  .Where(x => x.MySubObjectId == input)
  .Cast<MyObject>()
  .ToList()