Calling SubmitChanges on DataContext does not update database.

Question

In C# ASP.NET MVC application I use Link to SQL to provide data for my application. I have got simple database schema like this:

In my controller class I reference this data context called Model (as you can see on the right side of picture in properties) like this:

private Model model = new Model();

I've got a table (List) of Series rendered on my page. It renders properly and I was able to add delete functionality to delete Series like this:

public ActionResult Delete(int id) {
    model.Series.DeleteOnSubmit(model.Series.SingleOrDefault(s => s.ID == id));
    model.SubmitChanges();
    return RedirectToAction("Index");
}

Where appropriate action link looks like this:

<%: Html.ActionLink("Delete", "Delete", new { id=item.ID })%>

Also create (implemented in similar way) works fine. However edit does not work. My edit looks like this:

public ActionResult Edit(int id) {
    return View(model.Series.SingleOrDefault(s => s.ID == id));
}

[HttpPost]
public ActionResult Edit(Series series) {

    if (ModelState.IsValid) {
        UpdateModel(series);

        series.Title = series.Title + " some string to ensure title has changed";
        model.SubmitChanges();

        return RedirectToAction("Index");
    }
    return View(series);
}

I have controlled that my database has a primary key set up correctly. I debugged my application and found out that everything works as expected until the line with model.SubmitChanges();. This command does not apply the changes of Title property(or any other) against the database.

Please help.

EDIT: If I add this line: model.Series.Attach(series); just before model.SubmitChanges(); there is no change - edits still does not reflect to database. The instance passed to Edit method as a parameter is already attached to the data context model.

EDIT: Code of view that belongs to method Edit:

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" 
Inherits="System.Web.Mvc.ViewPage<TVSeriesInfoApp.Models.Series>" %>

<asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
Edit
</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">

<h2>Edit</h2>

<% using (Html.BeginForm()) {%>
    <%: Html.ValidationSummary(true) %>

    <fieldset>
        <legend>Fields</legend>

        <div class="editor-label">
            <%: Html.LabelFor(model => model.Title) %>
        </div>
        <div class="editor-field">
            <%: Html.TextBoxFor(model => model.Title) %>
            <%: Html.ValidationMessageFor(model => model.Title) %>
        </div>

        <div class="editor-label">
            <%: Html.LabelFor(model => model.Seasons) %>
        </div>
        <div class="editor-field">
            <%: Html.TextBoxFor(model => model.Seasons) %>
            <%: Html.ValidationMessageFor(model => model.Seasons) %>
        </div>

        <div class="editor-label">
            <%: Html.LabelFor(model => model.Stars) %>
        </div>
        <div class="editor-field">
            <%: Html.TextBoxFor(model => model.Stars) %>
            <%: Html.ValidationMessageFor(model => model.Stars) %>
        </div>

        <p>
            <input type="submit" value="Save" />
        </p>
    </fieldset>

<% } %>

<div>
    <%: Html.ActionLink("Back to List", "Index") %>
</div>

</asp:Content>

Answer 1

First, never ever "delete" with HTTP GET (this is exactly what you're doing with Html.ActionLink("Delete", "Delete", new { id=item.ID }).

As for edits, you first have to Attach your instance to the DataContext.

Answer 2

This is what our Edit Action would look like (Adjusted for your model):

[HttpPost]
public ActionResult Edit(int id, Series series)
{
    Series updatingSeries = model.Series.Single(s => s.ID == id);

    try
    {
        TryUpdateModel(updatingSeries);
        model.SubmitChanges();

        return RedirectToAction("Details", new { id = updatingSeries.ID });
    }
    catch
    {
        return View(updatingSeries);
    }
}

This can happen because the ModelState might not be valid in some cases. Have you done something to the View? Can you also post your View Code here please?