Model evaluating to false while saving to database

Question

So I have this problem when trying to save an item to the database in my asp.net mvc4 web app. I have three classes listed below

public class Posts
{
    [Key]
    public int PostID { get; set; }

    [Required(ErrorMessage="A Title is required for your Post")]
    [Display(Name="Title")]
    public string PostTitle { get; set; }


    [Required(ErrorMessage="This Field is Required")]
    [Display(Name = "Post")]
    public string PostContent { get; set; }

    [Required()]
    [DataType(DataType.DateTime)]
    public DateTime PostDate { get; set; }
    //public int AuthorID { get; set; }
    //public int CommentID { get; set; }

    [NotMapped]
    public virtual List<Comments> Comment { get; set; }
    public virtual Users user { get; set; }

}

and this class has a many to one relationship with the users class below

public class Users
{

    public Users()
    {
    }

    [Key]
    public int UserID { get; set; }

    [Required()]
    public string Firstname { get; set; }

    [Required()]
    public string Lastname { get; set; }

    [Required()]
    [DataType(DataType.Date, ErrorMessage="Enter a Valid Date")]
    public DateTime DOB { get; set; }

    //[Required()]
    //public string Photo { get; set; }

    [Required()]
    public string Sex { get; set; }

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

    public DateTime RegDate { get; set; }

    [Required()]
    [Column("Username")]
    //[Remote("doesUserNameExist", "Account", HttpMethod = "POST", ErrorMessage = "User name has already been taken. Please enter a different User name.")]
    public string Username { get; set; }

    [Required()]
    [DataType(DataType.Password)]
    public string Password { get; set; }

    public string PasswordSalt { get; set; }

    [System.ComponentModel.DataAnnotations.Compare("Password", ErrorMessage="Passwords do not match")]
    [DataType(DataType.Password)]
    //[NotMapped]
    //public string ConfirmPassword { get; set; }


    public virtual List<Posts> Post { get; set; }
    public virtual List<Comments> Comment { get; set; }

}

The database table for the Posts.cs class has a field called user_UserID which i assume is to store the id of the user that creates a post. I'm trying to save the posts to the database using the below code

@using (Html.BeginForm()) {
@Html.AntiForgeryToken()
@Html.ValidationSummary(true)

<fieldset>
    <legend>Posts</legend>

    <div class="form-group">
        @Html.LabelFor(model => model.PostTitle)
        @Html.TextBoxFor(model => model.PostTitle, new {@class = "form-control"})
        @Html.ValidationMessageFor(model => model.PostTitle)
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.PostContent)
        @Html.TextAreaFor(model => model.PostContent, new {@class = "form-control"})
        @Html.ValidationMessageFor(model => model.PostContent)
    </div>
        <input type="hidden" name="user.UserID" value="@Session["LoggedUserID"]" />

    <div>
        <input type="submit" value="Submit" />
    </div>
</fieldset>

}

As you can see, the user ID i'm saving to the database table is gotten from the user ID stored in the Session["LoggedUserID"] variable. The controller that handles the saving is below

public class PostsController : Controller
{
    //
    // GET: /Posts/
    BlogContext db = new BlogContext();
    public ActionResult Index()
    {
        return View();
    }

    [HttpGet]
    public ActionResult Create()
    {
        return View();
    }

    [HttpPost]
    public ActionResult Create(Posts Post)
    {
        var errors = ModelState.Values.SelectMany(v => v.Errors);
        try
        {
            if (ModelState.IsValid)
            {
                var newPost = db.Post.Create();
                newPost.PostTitle = Post.PostTitle;
                newPost.PostContent = Post.PostContent;
                newPost.PostDate = DateTime.Now;
                newPost.user.UserID = Post.user.UserID;
                db.Post.Add(newPost);
                db.SaveChanges();
                return RedirectToAction("Index", "Posts");
            }
            else
            {
                ModelState.AddModelError("", "Something is wrong with the model");
            }
        }

        catch (NullReferenceException ex)
        {
            Debug.WriteLine("Processor Usage" + ex.Message);
        }

        return View();
    }

}

I attached a breakpoint to the Modelstate.IsValid line and then debugged, but i noticed the ModelState is always evaluating to false and the ModelState.AddModelError is showing that is there is something wrong with validating the model. Ive tried all possible tweakings all to no avail. I need help. How can i save the Posts to the database table without this problem. Please what am i doing wrong?

Answer 1

I suspect ModelState is invalid because you are posting a value for user.UserId (the hidden input) which is initializing the property User which is invalid because of the validation attributes applied to other properties of User. It would be better to create a view model for creating new Posts that contain only the properties you need to display/edit. It is not necessary to include a property for User (the author of the post) since this can be set in the controller when you save the data (similar to what you are doing for the PostDate property

View model

public class PostVM
{
  [Required(ErrorMessage="A Title is required for your Post")]
  [Display(Name="Title")]
  public string Title { get; set; }
  [Required(ErrorMessage="This Field is Required")]
  [Display(Name = "Post")]
  public string Content { get; set; }
}

Controller

[HttpGet]
public ActionResult Create()
{
  PostVM model = new PostVM();
  return View(model);
}

[HttpPost]
public ActionResult Create(PostVM model)
{
  if(!ModelState.IsValid)
  {
    return View(model);
  }
  // Initialize new Posts
  // Map properties from the view model, set the user and date
  // Save and redirect
}

View

@model PostVM
@using (Html.BeginForm()) {
  ....
  <div class="form-group">
    @Html.LabelFor(model => model.Title)
    @Html.TextBoxFor(model => model.Title, new {@class = "form-control"})
    @Html.ValidationMessageFor(model => model.Title)
  </div>
  <div class="form-group">
    @Html.LabelFor(model => model.Content)
    @Html.TextAreaFor(model => model.Content, new {@class = "form-control"})
    @Html.ValidationMessageFor(model => model.Content)
  </div>
  <input type="submit" value="Submit" />
}