LINQ-按名称分组为Dictionary< string，List< T>>. [英] LINQ - grouping by name to Dictionary<string, List<T>>

问题描述

我正在构建图书馆应用.我有一本书的清单，其中有些书名重复(同一本书的副本很少).我想将列表转换为Dictionary>，其中字符串将是一本书的名称，而List将包含具有该名称的所有Book对象.

I am building a library app. I have a list of Books where some of them have a duplicate name (there are few copies of the same book). I would like to convert the list to Dictionary>, where the string would be the name of a book, and the List would contain all the Book objects with this name.

我已经设法做到了这一点:

I've managed to get this far:

var result  = queriedBooks
                .GroupBy(b => b.Name)
                .Where(g => g.Count() >= 1)
                .ToDictionary(b => b.Key, /// );

这就是我被困住的地方.我不知道该如何传递价值. Intellisense也无济于事，因为没有可用的Value属性.我想避免使用匿名对象，因为每个Book条目都有许多我在视图中使用的属性.

This is where I get stuck. I have no idea what to pass as a value. Intellisense does not help either, as there is no Value property available. I would like to avoid using anonymous objects, as each Book entry has many properties which I use in a view.

非常感谢！

推荐答案

作为替代方案，您可能只需要Lookup<String, Book>而不是麻烦的Dictionary<String, List<Book>>:

As an alternative you may want just Lookup<String, Book> instead of combersome Dictionary<String, List<Book>>:

   LookUp<String, Book> result = queriedBooks
     .ToLookup(book => book.Name);

对于Dictionary<String, List<Book>>:

   var result = queriedBooks
     .GroupBy(book => book.Name) 
     .ToDictionary(chunk => chunk.Key, chunk => chunk.ToList());

请注意，.Where(g => g.Count() >= 1)是冗余；

这篇关于LINQ-按名称分组为Dictionary< string，List< T>>.的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！