Where to add method prototype in case of accessing data from 3 related models in repository pattern

Question

I'm trying to create an ASP.NET MVC application using repostory pattern and dependency injection as design pattern. I have 3 related models

public class Category
{
    public int CategoryId { get; set; }
    public string Name { get; set; }
    public string TagName { get; set; }
    public string TagColor { get; set; }
    public string ImageUrl { get; set; }
    [ForeignKey("CategoryId")]
    public virtual ICollection<SubCategory> SubCategories { get; set; }
}
public class SubCategory
{

    public int SubCategoryId { get; set; }
    public int CategoryId { get; set; }
    public string Name { get; set; }
    public string TagName { get; set; }
    public string TagColor { get; set; }
    public string ImageUrl { get; set; }
    [ForeignKey("SubCategoryId")]
    public virtual ICollection<SubSubCategory> SubSubCategories { get; set; }
}
public class SubSubCategory
{
    public int SubSubCategoryId { get; set; }
    public int SubCategoryId { get; set; }
    public string Name { get; set; }
    public string TagName { get; set; }
    public string TagColor { get; set; }
    public string ImageUrl { get; set; }
}

Now I want to define a method that will return a JSON object of all the three related models containing the data will be containing Navigation Menu(Category), SubCategories under each Category and SubSubCategory as MenuItems under each SubCategory. So How do I define repository and the method prototype ?

Also if you can suggest me any method that can do all that what I've just explained earlier using Entityframework I will be grateful to you. Thank you

foreach (Category category in context.Categories)
{
    foreach (SubCategory subCategory in category.SubCategories)
    {
        foreach (SubSubCategory subSubCategory in subCategory.SubSubCategories)
        {
        }
    }
 }

This is what I'm doing to get all related data. If there is any good way to get all related data please let me know.

Answer 1

I suggest using one class instead of three different classes.

public class Category
{
    public int CategoryId { get; set; }
    public string Name { get; set; }
    public string TagName { get; set; }
    public string TagColor { get; set; }
    public string ImageUrl { get; set; }
    [ForeignKey("CategoryId")]
    public virtual ICollection<Category> SubCategories { get; set; }
}

This way every operation on all categories can be done with a simple recursive method.

private void SomeOperation(ICollection<Category> list)
{
    foreach (Category category in list)
    {
        //Do something
        SomeOperation(category.SubCategories);
    }
}

I hope it turns out to be helpful.