如何使用 LinQ To Entities 从多个表中获取数据行

Question

我首先使用 dbcontext 代码来获取基于此条件的以下类（表）的查询：

Creator != null && ArticleAttached != null && !IsCancelled

var ArticleStudentLiked = dbcontext.LearningActivites
  .Where(la => la.Creator != null && la.ArticleAttached != null && !la.IsCancelled)
  .Sum(la => la.ArticleAttached.StudentsLiked.Count);

  var NewsArticleComment = dbcontext.LearningActivites
  .Where(la => la.Creator != null && la.ArticleAttached != null && !la.IsCancelled)
  .Sum(la => la.ArticleAttached.Comments.Count);

以下方法仅返回计数：

• 文章学生喜欢
• 文章评论

我需要将查询中的记录行放入一个集合中，我可以将其传递给 View 以逐行显示

像这样：

文章标题、点赞数、评论数

如何使用 LinQ 获取这些：文章标题，编号。点赞数，评论数

Classes:


 public class LearningActivity
 {
   public virtual ArticleCreator Creator { get; set; }        
   public virtual ArticleCreator EditedBy { get; set; }        
   public virtual Teacher CreatedByTeacher { get; set; }   
   public virtual Article ArticleAttached { get; set; }   
   public virtual Article ArticleAttachedByOther { get; set; } 
   public bool IsCancelled { get; set; }
 }


 public class Article 
 {
   public string ArticleTitle {get;set;}
   public virtual IList<Teacher> TeachersLiked { get; set; }
   public virtual IList<Student> StudentsLiked { get; set; }
   public virtual IList<ArticleComment> Comments { get; set; }
 }


 public class Student
 {
   public virtual IList<ArticleCommentStudent> Comments { get; set; }
 }

谢谢

Answer 1

你可以试试这个

// LikeCount is total of Teacher and Student Likes 
// and where clause can be added before Select
var result = dbcontext.Classes
            .Select(x=> new { ArticleTitle = x.ArticleTitle, 
                              LikeCount = x.TeachersLiked.Count() + x.StudentsLiked.Count(), 
                              CommentCount= x.Comments.Count }).First();