CODEWITHSUNDEEP
c#asp.netasp.net-mvcmodelienumerable
haydnD
haydnD

Reputation: 2293

IEnumerable<> returns null

I'm returning a null in my code: (the var cat line)

public class CategoryItemsViewModel
{
    public ICategoriesRepository categoriesRepository;

    public IEnumerable<Categories> GetCategories()
    {
        var cat = categoriesRepository.Categories;

        return cat;

    }
}

here is the interface:

namespace SportsStore.Domain.Abstract
{
    public interface ICategoriesRepository
    {
        IQueryable<Categories> Categories { get; }
        void SaveCategory(Categories category);
        void DeleteCategory(Categories category);
    }
}

here is the class:

namespace SportsStore.Domain.Entities
{
    public class Categories
    {
        [Key]
        public int CategoryID { get; set; }
        public string CategoryName { get; set; }
    }

}

What am I doing wrong?

Upvotes: 1

Views: 1583

Answers (2)

Servy
Servy

Reputation: 203821

You haven't set anything that's not null to the Categories property in the ICategoriesRepository object, and you can't, with the given interface. You have a property with an automatic getter an no setter. This means it will only ever be able to return null. If there is a setter (either public or privite) then you would be able to set it to something else. (You would also need to have a line of code that actually did it.) You could also use a custom getter that actually returned something other than just the backing field. (This is common for derived data.)

Upvotes: 1

PeteGO
PeteGO

Reputation: 5791

What you have so far is fine - it's just incomplete.

You don't need a setter as someone else suggested either - in fact in this case it's probably better not to have one.

You do need a concrete implementation of your interface ICategoriesRepository eg:

public class CategoriesRepository : ICategoriesRepository
{
    private readonly ModelContainer db= new ModelContainer();

    public IQueryable<Categories> Categories 
    { 
        get
        {
            return this.db.Categories;
        }
    }

    public void SaveCategory(Categories category)
    {
        // TODO
    }

    public void DeleteCategory(Categories category)
    {
        // TODO
    }
}

Then you will need to add a line to your viewmodel:

public class CategoryItemsViewModel
{
    public ICategoriesRepository categoriesRepository;

    public IEnumerable<Categories> GetCategories()
    {
        // This is to instantiate your repository.  It may be a better idea to do this
        // when it is declared, above.
        categoriesRepository = new CategoriesRepository();

        var cat = categoriesRepository.Categories;

        return cat;

    }
}

Upvotes: 2

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