Question

I am creating a forum application in mvc3…

I have a link called Add New Comment on Post page where user can add the comments for that post… for creating new comment i have written following code….

 public ActionResult Addnew(int id)
    {
        Answer ans = new Answer();
        ans.QuestionQId = id;

        return View();
    }
    [HttpPost]
    public ActionResult Addnew(Answer ans,int id)
    {

        _db.Answers.Add(ans);
        _db.SaveChanges();
           return View("Details");
    }

but it is giving mean error whenever i try to save the code as follows:
Value cannot be null.
Parameter name: entity

I have two different table Question{id(pk), Question} and Answer{id(pk), ans, Qid(fk)}

All i want to do is While adding the comment for a perticular question, its Qid will be stored in answer database …..

Help me!!

View Related —

    @using (Html.BeginForm()) 
{ 
@Html.ValidationSummary(true)
 <fieldset> 
     <legend>Answer</legend> 
     <div class="editor-label">
       @Html.LabelFor(model => model.AId)
    </div> 
    <div class="editor-field">
      @Html.EditorFor(model => model.AId) 
      @Html.ValidationMessageFor(model => model.AId)
    </div>
    <div class="editor-label">
      @Html.LabelFor(model => model.Ans)
    </div> 
    <div class="editor-field">
      @Html.EditorFor(model => model.Ans) 
      @Html.ValidationMessageFor(model => model.Ans)
    </div>
    <div class="editor-label">
      @Html.LabelFor(model => model.QuestionQId)
    </div> <div class="display-field">
      @Html.DisplayFor(modelItem => modelItem.QuestionQId)
    </div> 
} 

Answer 1

I think you are not passing the Answer object to the view, may caused the problem. have you tried following

public ActionResult Addnew(int id)
    {
        Answer ans = new Answer();
        ans.QuestionQId = id;

        return View(ans);
    }