CODEWITHSUNDEEP
c#entity-frameworkasp.net-mvc-4many-to-manyrelational-database
mstfcck
mstfcck

Reputation: 731

Data isn't being updated in Entity Framework

I have three tables in my entity model of my database:

Models

I can add category more than one to a post. So tables are many to many.

I can add new a post with more then one category. There are no problem.

CreatePost action:

    [HttpPost]
    public ActionResult CreatePost(Post post, int[] categories)
    {
        post.CreatedDate = DateTime.Now;
        foreach (var category in categories)
        {
            post.Categories.Add(db.Categories.Find(category));
        }
        db.Posts.Add(post);
        db.SaveChanges();
        // Get categories from ListBox
        ViewData["Categories"] = new MultiSelectList(db.Categories.Select(c => new CategoryViewModel()
        {
            CategoryId = c.CategoryId,
            CategoryName = c.Name
        }), "CategoryId", "CategoryName");
        return View(post);
    }

But I can't update categories from post. I can't get error but it is not working.

EditPost:

    [HttpPost, ActionName("EditPost"), ValidateInput(false)]
    public ActionResult EditPost(Post post, int[] categories)
    {
        ViewData["Categories"] = new MultiSelectList(db.Categories.Select(c => new CategoryViewModel()
        {
            CategoryId = c.CategoryId,
            CategoryName = c.Name
        }), "CategoryId", "CategoryName");

        post.CreatedDate = DateTime.Now;
        // Clear all categories.
        post.Categories.Clear();
        foreach (var category in categories)
        {
            // Add new categories.
            post.Categories.Add(db.Categories.Find(category));
        }
        db.Entry(post).State = EntityState.Modified;
        db.SaveChanges();
        return RedirectToAction("Posts");
    }

Categories are not updated when I edit a posting. I don't get any error. How can I do that? Help please..

Upvotes: 1

Views: 185

Answers (2)

Gert Arnold
Gert Arnold

Reputation: 109089

The reason is that post.Categories must be loaded before EF can track changes to it.

db.Entry(post).State = EntityState.Modified; // Also attaches post to the context
db.Entry(post).Collection(p => p.Categories).Load();

// Clear all categories.
post.Categories.Clear();
// and so on

By the way, are you sure of post.CreatedDate = DateTime.Now; while the post is updated and not created?

Upvotes: 1

Shiraz Bhaiji
Shiraz Bhaiji

Reputation: 65391

The probable reason that nothing is saved is that SaveChanges does not find any changes to save. Therefore, it does nothing, and there is no error Message.

Try attaching the post to the context before adding the categories. Or setting the state on the categories:

foreach (var cat in post.Categories)

  this.Entry(cat).State = EntityState.Modified;

Upvotes: 0

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