C# 用于筛选5个嵌套类的Lambda表达式

我有一个嵌套对象，我必须根据更深层次对其进行过滤

这些是我的课程：

class Library    {
    public string Name { get; set; }
    public IList<Section> Sections { get; set; }
    public Library (string name, IList<Section> sections = null)  {
        Name = name;
        Sections = sections ?? new List<Section>();
    }
}

class Section    {
    public string Name { get; set; }
    public IList<Book> Books { get; set; }       
    public Section(string name, IList<Book> books = null) {
        Name = name;
        Books = books ?? new List<Book>();
    }
}

class Book {
    public string Name { get; set; }
    public IList<Word> Words { get; set; }
    public Book(string name, IList<Word> words = null) {
        Name = name;
        Words = words ?? new List<Word>();
    }
}

class Word {
    public string Name { get; set; }
    public IList<Character> Characters { get; set; }
    public Word(string name, IList<Character> characters = null) {
        Name = name;
        Characters = characters ?? new List<Character>();
    }
}

class Character {
    public char chrctr { get; set; }

    public Character(char character){
        chrctr = character;
    }
}

我想用lambda表达式替换嵌套的foreach以获取过滤对象，而不使用“add”和“get”函数创建新对象：

var filteredLibrary = new Library("filteredLibrary");
foreach (var section in library.Sections)
{
    foreach (var book in section.Books)
    {
        foreach (var word in book.Words)
        {
            var chars = word.Characters.Where(c => c.chrctr == 'd').ToList();
            if (chars.Count > 0)
            {
                filteredLibrary.Sections.Add(section);  //if it doesn't exist
                filteredLibrary.GetSection(section.Name).Books.Add(book);  //if it doesn't exist
                filteredLibrary.GetSection(section.Name).GetBook(book.Name).Words.Add(chars);  //if it doesn't exist
            }
        }
    }
}

---

我怎样才能做到这一点呢？

我不确定你是否应该走这条路，因为总体而言，整个事情看起来有点太复杂了。我会先尝试简化逻辑

否则，下面是ReSharper建议的（使用）

---

你能给我举个例子吗？你的嵌套的

foreach

有效吗？在我看来，您正在将一个现有的、未过滤的部分（它仍然拥有所有的书籍）添加到“过滤库”中，然后将所需的书籍重新添加到其中。意图很清楚（我认为），但是将代码直接转换为Linq不会得到您需要的结果。另外，最后一行不应该结束

.Words.Add（word）

，然后再将字符添加到单词中吗？这段代码就是一个例子，它不起作用。我的想法是使用lambda表达式获取过滤对象，而不使用“add”和“get”函数创建新对象

var filteredLibrary = new Library("filteredLibrary");
foreach (var section in library.Sections)
{
    foreach (var book in section.Books)
    {
        foreach (var word in book.Words)
        {
            var chars = word.Characters.Where(c => c.chrctr == 'd').ToList();
            if (chars.Count > 0)
            {
                filteredLibrary.Sections.Add(section);  //if it doesn't exist
                filteredLibrary.GetSection(section.Name).Books.Add(book);  //if it doesn't exist
                filteredLibrary.GetSection(section.Name).GetBook(book.Name).Words.Add(chars);  //if it doesn't exist
            }
        }
    }
}

var filteredLibrary = new Library("filteredLibrary");
foreach (var section in 
        from section in library.Sections 
        from book in section.Books 
        from word in book.Words 
        let chars = word.Characters
                        .Where(c => c.chrctr == 'd')
                        .ToList() 
        where chars.Count > 0
        select section)
{
    //if it doesn't exist
    filteredLibrary.Sections.Add(section);  
    filteredLibrary.GetSection(section.Name).Books.Add(book);
    filteredLibrary.GetSection(section.Name).GetBook(book.Name).Words.Add(chars);
}