How can I add an inner class List item into a ViewModel using FormMethod.Post?

Question

I know there have been many ?'s regarding @Html.Partial, @Html.RenderPartial, and even using @Html.Action used with [ChildActionOnly] and PartialView();, but my problem is a little more complex as it involves FormMethod.Post so any help would be greatly appreciated for this newbie. First let me show you the two ViewModels before I explain my problem:

    public class Article 
    {
    public int ArticleId {get; set;}
    public int UserId {get; set;}
    public virtual ICollection<Comment> Comments {get; set;}
    //...
    }

    public class Comment
    {
    public Comment(int AId, int UId)
    {
        UserId = UId;
        ArticleId = AId;
        Content = "";
        //...
    }
    public int CommentId {get; set;}
    public int ArticleId {get; set;}
    public int UserId {get; set;}
    //...
    }

So my @model BlogSite.Models.Article view has a partial view that queries all the comments based on the ArticleId and injects them into this View ~/Article/Details/5 (Want to reroute the URL based on title but that is for another day) using @Html.Action("GetCommentsById", "Article", new { id = Model.ArticleId }) just fine, but I used the seed method to add the comments to the db, so my problem is when using forms. I need to pass the ArticleId prior to submitting the FormMethod.Post in the PartialView @model BlogSite.Models.Comment.

The following is what I tried to do and failed as the Comment object is null.

Here is the _AddPostPartial that is injected into Details.cshtml:

@model BlogSite.Models.Comment

@using (Html.BeginForm("Post", "Article", FormMethod.Post))
    {
    @Html.ValidationSummary(true)
    <div id="post-area">
        @Html.TextBoxFor(m => m.Content, new { @class = "textarea" })
    </div>
    <div id="post-info">
        <input type="submit" value="Post" title="Post" class="post-button" />
    </div>
}

Here is the portion of Detail.cshtml and the options I have tried:

 @Html.Action("AddComment", new { AId = Model.ArticleId, UId = WebSecurity.CurrentUserId })

Here is both GET/POST Controller Actions:

[HttpGet,  ChildActionOnly]
ActionResult AddComment(int AId, int UId)
{
Comment comment = new Comment(AId, UId);

return PartialView("_AddPostPartial", comment);
}

 [HttpPost,ActionName("Post")]
 public ActionResult AddComment(Comment comment)
 {
        if (ModelState.IsValid)
        {
            unitOfWork.ArticleRepository.InsertComment(comment);
            RedirectToAction("Details", "Article", new { id = comment.ArticleId });
        }

        return PartialView("_AddPostPartial", comment);
 }

The problem is when I debug the app the comment in the HttpGet is not holding the values of the two ints. I thought that Comment object would be on the heap but it says it is null. Can someone point me in the right direction? I know Ajax and JSON will ultimately be the solution I use but I still have to get these Actions to work prior. Thanks in advance! Please feel free to be as critical as possible :-)

*NOTE I was wondering if I even need the PartialView to be of @Model.Comment? I can essentially pass the parameters I need to create the Comment object from the View, but doesn't there have to be a way to use forms to create new objects within a ViewModel that are not an instance of the ViewModel in the Main View? I also understand that I am essentially calling the same action within the action using the [ActionName("Post")] so I don't like how I am doing that so I am sure that is wrong.

---

So yes I am an idiot. I walked away for a few minutes and went to the store and came back and figured it out. Note to self: Always make sure you use the keyword return even when RedirectToAction! Ok I will share how I fixed this issue so if anyone else has a problem with this they wont spend hours like I did.

Here is my call to my Action in Main View (Details.cshtml):

@Html.Action("AddComment", "Article", new { AId = Model.ArticleId })

Here is the Controller Action AddComment which returns PartialView:

[HttpGet]
public ActionResult AddComment(int AId)
{
        Comment comment = new Comment(AId, WebSecurity.CurrentUserId);

        return PartialView("_AddPostPartial", comment);
}

Note: Must instantiate the ModelView object and pass it to the Partial View

Here is the _AddPostPartial PartialView which hosts the Form that will post the instantiated object to the server. I will then call my InsertComment(Comment comment) into my UoW which has all of my repositories as you will see in ActionResult Post:

@model BlogSite.Models.Comment


    @using (Html.BeginForm("Post", "Article", FormMethod.Post)){
        @Html.ValidationSummary(true)
        @Html.HiddenFor(model => model.ArticleId)
        <div id="post-area">
            @Html.TextAreaFor(m => m.Content, new { @id = "comment", @class = "textarea", @name = "comment" })
        </div>

        <div id="post-info">
            <input type="submit" value="Post" class="post-button" />
        </div>
    }
        <script>
            $("form").submit(function (event) {
                $("textarea[name=comment]").val("");
            });

        </script>

Here is the ActionResult Post:

[HttpPost]
public ActionResult Post(Comment comment)
{

    if (ModelState.IsValid)
    {
    unitOfWork.ArticleRepository.InsertComment(comment);
     return RedirectToAction("Details", "Article", new { id = comment.ArticleId });
    }

    return PartialView("_AddPostPartial", comment);
}

By using the UnitOfWork I ensure that I will re-inject the updated Comments for the Article (ArticleId = 5 for example) This function is located in a repository which is instantiated in the UnitOfWork:

    public void InsertComment(Comment comment)
    {
        // actual insert of comment into database
        context.Comments.Add(comment);
        Article article = context.Articles.Find(comment.ArticleId);
        UserProfile commenter = context.Users.Find(comment.UserId);
        // in-memory List for both User and Article 
        article.Comments.Add(comment);
        commenter.Comments.Add(comment);
        context.Entry(article).State = EntityState.Modified;
        context.Entry(commenter).State = EntityState.Modified;
        Save();
    }

NOTE: I think is important to Add the Comments to both the User's and the Article's virtual List. When I took out the latter two Adds the new comment did not render when return RedirectToAction("Details", "Article", new {comment.ArticleId});which makes me think they create the ER in-memory? My actual Article and User domain models have ICollection<Comment> Comments {get; set; } so maybe that is why I need to do this. I would think that using an interface would be much better in these circumstances, but correct me if I am wrong?