我有一个注释类,在创建时存储用户的id,根据我的理解,实体框架将此Id映射到用户。这在最初加载视图时有效。但是当我添加一个新的注释,并由于某种原因返回PartialView时,Author(应用程序用户)为null并抛出异常。但是,如果我重新加载页面,则会显示新注释,并显示正确的ApplicationUser信息。
public class Comment
{
public Guid ID { get; set; }
public string Text { get; set; }
[Required]
public string AuthorId { get; set; }
[ForeignKey("AuthorId")]
public virtual ApplicationUser Author { get; set; }
public DateTime DateSubmitted { get; set; }
public Guid PostID { get; set; }
public virtual Post Post { get; set; }
}
我使用ViewModel处理视图上的数据。
public class CommentViewModel
{
public string Text { get; set; }
public Guid PostID { get; set; }
public List<Comment> CommentList { get; set; }
}
这是我的控制器动作。
public ActionResult CreateComment(CommentViewModel viewModel)
{
if (ModelState.IsValid)
{
var manager = new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(new ApplicationDbContext()));
var currentUser = manager.FindById(User.Identity.GetUserId());
var comment = new Comment
{
ID = Guid.NewGuid(),
AuthorId = currentUser.Id,
DateSubmitted = DateTime.Now,
PostID = viewModel.PostID,
Text = viewModel.Text
};
Debug.Write("PostID:" + comment.PostID + "Author: " + "Text: " + comment.Text);
db.Comments.Add(comment);
db.SaveChanges();
CommentViewModel model = new CommentViewModel();
model.CommentList = db.Comments.Where(i => i.PostID == comment.PostID).OrderByDescending(c => c.DateSubmitted).ToList();
return PartialView(model);
}
else
{
Debug.Write("not valid");
}
return PartialView(viewModel);
}
此foreach显示CommentList中的所有注释。提交新评论时,它会在显示@ item.Author.Id的行上崩溃。
foreach (var item in Model.CommentList)
{
<div class="row">
<div class="col-sm-1">
<div class="thumbnail">
<img class="img-responsive user-photo" src="https://ssl.gstatic.com/accounts/ui/avatar_2x.png">
</div><!-- /thumbnail -->
</div><!-- /col-sm-1 -->
<div class="col-sm-5">
<div class="panel panel-default">
<div class="panel-heading">
<strong>@item.Author.Id</strong>
<time class="timeago" datetime="@item.DateSubmitted"></time>
</div>
<div class="panel-body">
@item.Text
</div><!-- /panel-body -->
</div><!-- /panel panel-default -->
</div><!-- /col-sm-5 -->
</div>
}
答案 0 :(得分:1)
Comment.Author是虚拟的,因此您需要在保存后明确加载它。变化:
model.CommentList = db.Comments.Where(i => i.PostID == comment.PostID).OrderByDescending(c => c.DateSubmitted).ToList();
要:
model.CommentList = db.Comments
.Include(c => c.Author)
.Where(i => i.PostID == comment.PostID)
.OrderByDescending(c => c.DateSubmitted).ToList();
请参阅https://msdn.microsoft.com/en-us/library/gg671236%28v=vs.103%29.aspx#Anchor_1