在ASP.NET MVC中从数据库检索数据时遇到问题

Question

I have created 5 tables in my database:

1. Categories
2. Product (FK, Category)
3. Options
4. OptionGroups
5. ProductOptions (FK, Options, OptionGroups, Products)

In case of any confusion I have attached my ERD here ..

I'm stuck at the scenario that I want a list of categories on my homepage. When I select any one of them, it would show the option groups accordingly and in this option group, options will be shown. How can I achieve this by using Entity Framework and LINQ queries?

Please help me with the controller logic. I have mapped the models as shown in the database. And also please help if I am making the database relation wrong?

Edit

I have got the list of OptionGroup by making a FK relation from Category to OptionGroups.. Now i want to get the list of each option group in the same action method.. Please help me with this linq query and then i want to retreive the product from that specific option.. please help me with that linq query too..

Controller

[HttpPost]
        public ActionResult GetSubCategories(int btnValue)
        {

            Entities entity = new Entities();
            HomeRoot root = new HomeRoot();
            root.OptionGroups = entity.OptionGroups.Where(m => m.CategoryID == btnValue).ToList();
            //Missing My logic Here 
            return View("SubCategories",root);

        }

Models

 public partial class ProductOption
    {
        public int ProductOptionID { get; set; }
        public int OptionID { get; set; }
        public int OptionGroupID { get; set; }
        public int ProductID { get; set; }
        public double OptionPriceIncrement { get; set; }

        public virtual OptionGroup OptionGroup { get; set; }
        public virtual Option Option { get; set; }
        public virtual Product Product { get; set; }
    }


 public partial class Product
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public Product()
    {
        this.OrderDetails = new HashSet<OrderDetail>();
        this.ProductOptions = new HashSet<ProductOption>();
    }

    public int ProductID { get; set; }
    public string ProductSKU { get; set; }
    public string ProductName { get; set; }
    public Nullable<double> ProductPrice { get; set; }
    public Nullable<double> ProductWeight { get; set; }
    public string ProductCartDesc { get; set; }
    public string ProductShortDesc { get; set; }
    public string ProductLongDesc { get; set; }
    public string ProductThumb { get; set; }
    public string ProductImage { get; set; }
    public Nullable<int> CategoryID { get; set; }
    public byte[] ProductUpdateDate { get; set; }
    public Nullable<double> ProductStock { get; set; }
    public Nullable<byte> ProductLive { get; set; }
    public Nullable<byte> ProductUnlimited { get; set; }
    public string ProductLocation { get; set; }
    public string ProductColor { get; set; }

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<OrderDetail> OrderDetails { get; set; }
    public virtual ProductCategory ProductCategory { get; set; }
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<ProductOption> ProductOptions { get; set; }
}

  public partial class OptionGroup
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public OptionGroup()
    {
        this.ProductOptions = new HashSet<ProductOption>();
    }

    public int OptionGroupID { get; set; }
    public string OptionGroupName { get; set; }
    public Nullable<int> CategoryID { get; set; }

    public virtual ProductCategory ProductCategory { get; set; }
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<ProductOption> ProductOptions { get; set; }
}
public partial class Option
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public Option()
    {
        this.ProductOptions = new HashSet<ProductOption>();
    }

    public int OptionID { get; set; }
    public string OptionName { get; set; }

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<ProductOption> ProductOptions { get; set; }
}

Answer 1

1.

In your case write like this to get selected category option groups list:

var SelectedCategoryOptionGroup= Context.ProductOptions
                .Where(po=>po.Product.CategoryID ==SelectedCategoryID)
                .Select(po=>po.OptionGroup)
                .Distinct();

Writes by Entityframework with Lazy loading technique. SelectedCategoryID is your home page selected category id.

2.

Otherwise: If your OptionGroup direct related with Category , you must reference OptionGroup directly to Category. in this case you more easy to achieve to target.