LINQ - Add to database does not show up

I don't know why but in all tutorials I've seen there is DBObject.TableObject.Add(newObject);. I am not sure why but in my case there is no.

Code

[HttpPost]
public ActionResult Index(Post newPost)
{
    if (TryUpdateModel(newPost) == true)
    {
        string[] tagList = { "tag1", "tag2", "tag3"};
        _db.Posts.InsertOnSubmit(newPost);
        _db.SubmitChanges();


        foreach (string tag in tagList)
        {
            var newTag = new Tag();
            if (_db.Tags.Any(x => x.TagName == tag))
            {
                newTag = (from t in _db.Tags
                              where t.TagName == tag
                              select t).Single();
            }
            else
            {
                newTag = new Tag()
                {
                    TagName = tag
                };
            }

            // Does not work
            _db.Tags.Add(newTag);

            var postTag = new PostTag()
            {
                Tag = newTag,
                Post = newPost
            };

            // Does not work
            _db.PostTags.Add(postTag);
        }

        return Content(Convert.ToString(newPost.ID));
        return RedirectToAction("List");
    }
    else
    {
        return Content("Fail.");
    }
}

Error

Error   1   'System.Data.Linq.Table<MvcApplication1.Models.Tag>' does not contain a definition for 'Add' and no extension method 'Add' accepting a first argument of type 'System.Data.Linq.Table<MvcApplication1.Models.Tag>' could be found (are you missing a using directive or an assembly reference?) C:\Users\Qmal\documents\visual studio 2010\Projects\MvcApplication1\MvcApplication1\Controllers\HomeController.cs   47  30  MvcApplication1

Reference? I have all LINQ references included, this is strange to开发者_StackOverflow中文版 me.

P.S. I'm not eve sure if I'm doing it right, but still it is weird.

---

You are probably looking at older tutorials...the following should be what you need (instead of Add)

_db.Tags.InsertOnSubmit( newTag );
_db.SubmitChanges( );

---

As the error message says, the problem is that the Add method you're using doesn't accept a parameter of type System.Data.Linq.Table<MvcApplication1.Models.Tag>.

By the looks of it the Add method is expecting a type of Tag. You could do something like:

newTag = (from t in _db.Tags
               where t.TagName == tag
                select t).Single()
                           .Select(m => new Tag(){
                             TagName = m.Name
                            });