Question

I’ve got a simple form that creates Categories with a name and a List of Cars assigned to them.

Everything works fine minus the fact that for each entry in the DB I get a second one before that is null everywhere except for the parent BrandId.

[HttpPost]
public ActionResult AddNewCategory(AddNewCategoryPostViewModel categoryInfo)
{
    var brand = _repository.GetBrandById(categoryInfo.BrandId);
    if (categoryInfo.Name == null || categoryInfo.Cars == null)
    {
        if (categoryInfo.Name == null)
        {
            ModelState.AddModelError("Name", "The name cannot be empty.");
        }

        if (categoryInfo.Cars == null)
        {
            ModelState.AddModelError("Cars", "At least one car must be selected.");
        }

        var cars = _insplib.GetDevCategorysForProject((int)brand.Id);

        ViewBag.Cars = cars;
        ViewBag.Selectedcars = categoryInfo.Cars;

        return View(new Category()
                        {
                            Brand = brand
                        });
    }

    var category = new Category()
                        {
                            DateEntered = DateTime.Now,
                            IsArchived = false,
                            Name = categoryInfo.Name,
                            BrandId = categoryInfo.BrandId
                        };

    _repository.AddOrUpdateCategory(category);

    // more code here added to add the cars, but not relevant to this issue.

    return RedirectToRoute("Category", new { brand = category.Brand.ShortName, categoryId = category.Id });
}

My repository method is:

public Category AddOrUpdateCategory(Category category)
{
    if (category.Id == 0)
        _context.AddToCategorys(category);

    _context.SaveChanges();

    return category;
}

As you can see it’s a pretty straight forward POST, yet every time I create a Category, I get two entries:

ID  Name    DateEntered IsArchived  
5   NULL    NULL    NULL    4
6   NewCategory 10/6/2011   False   4

My trick has been to simply go through the table and remove any Category that has null values in Name. But that’s obviously not resolving the actual issue.

Answer 1

As per the comments, It is actually your GET that will be creating the blank record when it passes a new Category() to the view.
Some of the ORM’s detect new’d up objects and add them to your context for you. Which helpfully creates confusing issues like this one.