Question

I’m using LINQtoSQL to create cascading deletes IE: if Category is deleted then all the Products in that category are also deleted.

I have a Products repository set up already (IProductsRepository) and now I’m working in my Category repository to add the business domain logic for the cascade.

Products repository has this method :

public void DeleteProducts(IList<Product> Products)
    {
        foreach (Product product in Products)
        {
            productsTable.DeleteOnSubmit(product);
        }
        productsTable.Context.SubmitChanges();
    }

Then I am creating a delete category method in my Category repository:

    public void DeleteCategory(Category category)
    {
        IProductsRepository productsRepository;

        var CascadeDeleteProducts =
            from Products in productsRepository.Products
            where Products.CategoryID == category.CategoryID
            select Products;

        productsRepository.DeleteProducts(CascadeDeleteProducts.ToList());

        categoriesTable.DeleteOnSubmit(category);
        categoriesTable.Context.SubmitChanges();
    }

Visual Studio 2010 gives me an error in the above function for this line: from Products in productsRepository.Products. It says

Use of unassigned local variable ‘productsrepository’

What could be causing this error? I’m creating the products repository through DI with this line: IProductsRepository productsRepository;. What am i doing wrong?

Edit

I neglected to mention that I am using Ninject to instatiate the product repository. So I beleieve that this line:IProductsRepository productsRepository; is effectually declaring and initializing the product repository.

Answer 1

You’re creating an instance of your repository, but you never initialize it.

The line should look something like:

IProductRepository productsRepository = new ProductRepository();

Either that or you should allow the caller to inject (either method or constructor) the repository:

public void DeleteCategory(Category category, 
    IProductRepository productRepository)
{
}

UPDATE

If you’re using nInject for your dependency injection, your method declaration should look like (this assumes you have nInject configured correctly to Inject the Dependency):

[Inject]
public void DeleteCategory(Category category,
    IProductRepository productRepository)
{
}