comment db not getting updated in asp .net

Question

I am trying to create a simple blog application using asp.net. I am a novice and trying to teach myself c# and asp .net mvc.

The problem that I am facing is that when I try to add a comment to a post then it doesn't work. I do get a comment attached to the post but it doesn't display anything. Also, when I check the database - it just contains Null fields except for the BlogID field. What am I doing wrong?

My code is below:

Blog - class

public class Blog
{
    public int BlogID { get; set; }
    public string Title { get; set; }
    public string Writer { get; set; }

    [DataType(DataType.MultilineText)]
    public string Excerpt { get; set; }

    [DataType(DataType.MultilineText)]
    public string Content { get; set; }

    [DataType(DataType.Date)]
    public DateTime PublishDate { get; set; }

    public virtual ICollection<Comment> Comments { get; set; }
}

Comment - class

public class Comment
    {
        public int CommentID { get; set; }
        public string Name { get; set; }

        [DataType(DataType.EmailAddress)]
        public string Email { get; set; }

        [DataType(DataType.MultilineText)]
        public string CommentBody { get; set; }

        public virtual int BlogID { get; set; } 
        public virtual Blog Blog { get; set; }
    }

BlogDetailViewModel

public class BlogDetailsViewModel
{
    public Blog Blog { get; set; }
    public Comment Comment { get; set; }
}

Blog - Details controller

public ViewResult Details(int id)
{

    Blog blog = db.Blogs.Find(id);
    BlogDetailsViewModel viewModel = new BlogDetailsViewModel {Blog = blog};
    return View(viewModel);
}

Blog Details - view

@model NPLHBlog.ViewModels.BlogDetailsViewModel

has code to display blogpost + comment form at end of blog details page below:

   @using (Html.BeginForm("Create", "Comment"))
    {
        <input type="hidden" name="BlogID" value="@Model.Blog.BlogID" />
        <div class="editor-label">
            @Html.LabelFor(model => model.Comment.Name)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.Comment.Name)
            @Html.ValidationMessageFor(model => model.Comment.Name)
        </div>

        <div class="editor-label">
            @Html.LabelFor(model => model.Comment.Email)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.Comment.Email)
            @Html.ValidationMessageFor(model => model.Comment.Email)
        </div>            

        <div class="editor-label">
            @Html.LabelFor(model => model.Comment.CommentBody)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.Comment.CommentBody)
            @Html.ValidationMessageFor(model => model.Comment.CommentBody)
        </div>
        <p>
            <input type="submit" value="Add Comment" />
        </p>

comment - create controller

public class CommentController : Controller
{
    private NPLHBlogDb db = new NPLHBlogDb();

    //
    // GET: /Comment/

    public ActionResult Create(Comment c)
    {
        Blog blog = db.Blogs.Single(b => b.BlogID == c.BlogID);
        blog.Comments.Add(c);
        db.SaveChanges();
        return RedirectToAction("Details", "Blog", new { ID = c.BlogID });
    }

Any help would be grateful.

Answer 1

I think you should add HttpPost attribute to the Create ActionResult method.

[HttpPost]
public ActionResult Create(Comment c)
    {
        Blog blog = db.Blogs.Single(b => b.BlogID == c.BlogID);
        blog.Comments.Add(c);
        db.SaveChanges();
        return RedirectToAction("Details", "Blog", new { ID = c.BlogID });
    }

Answer 2

Found the answer ... I updated the create action of comment controller to:

public ActionResult Create(BlogDetailsViewModel viewModel)
{
    Blog blog = db.Blogs.Single(b => b.BlogID == viewModel.Comment.BlogID);
    Comment c = viewModel.Comment;
    blog.Comments.Add(c);
    db.SaveChanges();
    return RedirectToAction("Details", "Blog", new { ID = c.BlogID });
}

Answer 3

Try associating the Comment with the Blog before saving because the Comment instance that is passed as action argument has its Blog property null:

public ActionResult Create(Comment c)
{
    Blog blog = db.Blogs.Single(b => b.BlogID == c.BlogID);
    blog.Comments.Add(c);

    // associate the comment with the blog that you have retrieved
    c.Blog = blog;

    db.SaveChanges();
    return RedirectToAction("Details", "Blog", new { ID = c.BlogID });
}