从与其它标准列表中删除列表项 [英] Remove items of list from another lists with criteria

问题描述

我有作家的名单。

public class Writers{   
    long WriterID { get;set; }
}

另外我有类型的文章两份清单。

Also I have two lists of type Article.

public class Article{
    long ArticleID { get; set; }
    long WriterID { get; set; }
    //and others    
}

因此​​code我已经是：

so the code i have is:

List<Article> ArticleList = GetList(1);
List<Article> AnotherArticleList = AnotherList(2);
List<Writers> listWriters = GetAllForbiddenWriters();

我想从 ArticleList ， AnotherArticleList 删除这些记录，其中 WriterID 从 listWriters WriterID 。如何做到这一点的LINQ？

I want to remove those records from ArticleList, AnotherArticleList where WriterID matches from listWriters WriterID. How to do this in LINQ?

推荐答案

如果你确实有一个名单，其中，T＆GT; ，我建议你使用<一个href="http://msdn.microsoft.com/en-us/library/wdka673a.aspx"><$c$c>List<T>.RemoveAll,构建了一套作家的ID之后：

If you've actually got a List<T>, I suggest you use List<T>.RemoveAll, after constructing a set of writer IDs:

HashSet<long> writerIds = new HashSet<long>(listWriters.Select(x => x.WriterID));

articleList.RemoveAll(x => writerIds.Contains(x.WriterId));
anotherArticleList.RemoveAll(x => writerIds.Contains(x.WriterId));

如果您的不的想使用LINQ，你可以使用：

If you do want to use LINQ, you could use:

articleList = articleList.Where(x => !writerIds.Contains(x.WriterId))
                         .ToList();
anotherArticleList = anotherArticleList
                         .Where(x => !writerIds.Contains(x.WriterId))
                         .ToList();

请注意，这个改变的变量的，但不修改现有的列表 - 所以，如果有任何其他引用相同的列表，他们将不会看到任何变化。 （而 removeall过修改现有列表。）

Note that this changes the variable but doesn't modify the existing list - so if there are any other references to the same list, they won't see any changes. (Whereas RemoveAll modifies the existing list.)

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