Question

我有一个名为博客的模型：

public class Blog
    {
        [Key]
        public int blogId { get; set; }
        [Required]
        public string blogTitle { get; set; }
        public string imagePath { get; set; }
        [Required, DataType(DataType.Html)]
        public string blogDescription { get; set; }
        [DataType(DataType.DateTime)]
        public DateTime blogDateTime { get; set; }
        [Required]
        public bool isPublished { get; set; }

        [Required]
        public BlogCategory blogCategory { get; set; }
        public List<Comments> blogComments { get; set; }
    }

和另一个模型评论：

public class Comments
    {
        [Key]
        public int authorId { get; set; }
        [Required]
        public string commentAuthor { get; set; }
        [DataType(DataType.Date)]
        public DateTime commentDate { get; set; }
        public bool isHidden { get; set; }
        [Required, DataType(DataType.EmailAddress)]
        public string commentAuthorEmail { get; set; }
        [Required]
        public string commentDescription { get; set; }
        public Blog Blog { get; set; }
    }

在Blogs控制器中，我要访问isHidden = false

处的所有评论。

我尝试过的是：

var blog = await _context.Blog
           .Include(cat => cat.blogCategory)
           .Include(comments => comments.blogComments.Any(c => !c.isHidden))
           .FirstOrDefaultAsync(m => m.blogId == id);

但我得到的唯一例外是

An unhandled exception occurred while processing the request.
InvalidOperationException: The Include property lambda expression 'comments => comments.blogComments.Find(c => Not(c.isHidden))' is invalid. The expression should represent a property access: 't => t.MyProperty'. To target navigations declared on derived types, specify an explicitly typed lambda parameter of the target type, E.g. '(Derived d) => d.MyProperty'.

我该如何解决这个问题？

Answer 1

function addHandlers() {
  for (i = 0; i < squaresPerSide * squaresPerSide; i++) {
    console.log(document.getElementsByClassName('boxes')[i]);
    document.getElementsByClassName('boxes')[i].addEventListener("mouseover",function (event){                                               //Eventlistener to change the background color when mouse over is done.
       //console.log(event);
        event.target.style.backgroundColor = 'green';
    }
    );
  }
}

由于它是一个IQueryable，因此结果相同。它只会返回隐藏博客评论的评论。考虑到您要返回所有博客，而不仅仅是返回其注释被隐藏的博客。

Answer 2

您无法在EF核心的Include中进行过滤，请尝试使用以下代码代替

var blog = await _context.Blog
       .Include(cat => cat.blogCategory)
       .Include(comments => comments.blogComments)
       .FirstOrDefaultAsync(m => m.blogId == id);

blog.blogComments = blog.blogComments.Where(b => b.isHidden == false).ToList();

请参阅Filtering on Include in EF Core

Answer 3

您必须使用实体框架投影。

var blog = await _context.Blog
.Select(p => new Blog
{
    blogComments  = p.blogComments.Where(s => !s.isHidden )
}.FirstOrDefaultAsync(m => m.blogId == id);

Answer 4

布尔值true为false，因此请尝试： //未测试

(comments => comments.blogComments.where(c=>c.isHidden==false))

通过包括的EF核心访问权限列表

4 个答案: