Add ID from URL in MVC - asp.net-mvc

Question

Im just starting out with MVC and i'm in the learning phase. I'm currently stuck with this problem. In my soulution i got these two tables.
TopicTable
-TopId
-TopName
ContentTable
-ContId
-TopId
-Content
I want while i'm in the Topic Detailes-view to be able to create new content.
In the detailes.cshtml file i've added:
#Html.ActionLink("Create New Content", "Create", "Content", new { ID = Model.TopicId}, null)` which will display in URL: localhost/Content/Create/1
In my ContentController ive got this, and i get this error when submitting "Validation failed for one or more entities. See 'EntityValidationErrors' property for more details."
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(int Id)
{
ContentModel content = new ContentModel();
if (ModelState.IsValid)
{
content.TopId = Id;
db.ContentModel.Add(content);
db.SaveChanges();
return RedirectToAction("Index");
}
return View(content)
}
The View:
#model WebApplication2.Models.ContentModel
#{
ViewBag.Title = "Create";
}
#using (Html.BeginForm())
{
#Html.AntiForgeryToken()
<div class="form-horizontal">
<h4>JobOfferModel</h4>
<hr />
#Html.ValidationSummary(true)
<div class="form-group">
#Html.LabelFor(model => model.Content, new { #class = "control-label col-md-2" })
<div class="col-md-10">
#Html.EditorFor(model => model.Content)
#Html.ValidationMessageFor(model => model.Content)
</div>
</div>
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<input type="submit" value="Create" class="btn btn-default" />
</div>
</div>
</div>
}
<div>
#Html.ActionLink("Back to List", "Index")
</div>
#section Scripts {
#Scripts.Render("~/bundles/jqueryval")
}
Model:
public class Topic
{
[Display(Name = "Id")]
public virtual int TopicId{ get; set; }
[Display(Name = "Name")]
public virtual string TopicName{ get; set; }
}
public class Content
{
[Display(Name = "Id")]
[Display(Name = "Id")]
public virtual int ContentId{ get; set; }
[Display(Name = "TopicId")]
public virtual string TopicId{ get; set; }
[AllowHtml]
[Display(Name = "Innihald")]
public virtual string Content { get; set; }
}
So when i'm creating new content the topId value will automaticly be added to the content table.
Would love some help,, Gracias

Answer 1

#Html.ActionLink() is a call to a GET method. You need a GET to return a view that renders the form, and a POST method to receive and save the form data
public ActionResult Create(int ID)
{
Content model = new Content();
model.TopicId = ID; // note TopicId should be int, not string
return View(model);
}
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(Content model)
{
if(!ModelState.IsValid)
{
return View(model);
}
// save your model and redirect.
}
View (divs etc omitted)
#model WebApplication2.Models.Content
....
#using (Html.BeginForm())
{
#Html.AntiForgeryToken()
#Html.ValidationSummary(true)
#Html.HiddenFor(m => m.TopicId) // for postback
#Html.LabelFor(model => model.Content, new { #class = "control-label col-md-2" })
#Html.TextBoxFor(model => model.Content)
#Html.ValidationMessageFor(model => model.Content)
<input type="submit" value="Create" class="btn btn-default" />
}
....