通过相关的ViewModel DTO C#实现多对多

public class Article
{
    public int Id { get; set; }
    public string Title { get; set; }
    public List<ArticleTag> ArticleTags { get; set; }
}

public class Tag
{
    public int Id { get; set; }
    public string Name { get; set; }
    public List<ArticleTag> ArticleTags { get; set: set; }
}

public class ArticleTag
{
    public int ArticleId { get; set; }
    public Article Article { get; set; }
    public int TagId { get; set; }
    public Tag Tag { get; set; }
}

public class ArticleViewModel
{
    public int Id { get; set; }
    public string Title { get; set; }
    public List<Tag> Tags { get; set; }
}

public List<ArticleViewModel> GetArticlesWithTags()
{
    var articles = _context.Articles.Include(a => a.ArticleTags).ThenInclude(at => at.Tag).ToList();
    var articleViewModels = new List<ArticleViewModel>();

    foreach (var article in articles)
    {
        var tags = article.ArticleTags.Select(at => at.Tag).Distinct().ToList();
        articleViewModels.Add(new ArticleViewModel
        {
            Id = article.Id,
            Title = article.Title,
            Tags = tags
        });
    }

    return articleViewModels;
}

// 使用缓存示例
public List<ArticleViewModel> GetArticlesWithTags()
{
    var cacheKey = "articles_with_tags";
    var cachedData = _cache.Get<List<ArticleViewModel>>(cacheKey);

    if (cachedData != null)
    {
        return cachedData;
    }

    var articles = _context.Articles.Include(a => a.ArticleTags).ThenInclude(at => at.Tag).ToList();
    var articleViewModels = new List<ArticleViewModel>();

    foreach (var article in articles)
    {
        var tags = article.ArticleTags.Select(at => at.Tag).Distinct().ToList();
        articleViewModels.Add(new ArticleViewModel
        {
            Id = article.Id,
            Title = article.Title,
            Tags = tags
        });
    }

    _cache.Set(cacheKey, articleViewModels, TimeSpan.FromMinutes(10));

    return articleViewModels;
}