实体框架多对多关系查询

Question

I'm working on a project where I have two models that are related too each other. Books and BookCategories. I'm stuck on a function where I want to show all books that are in a certain category. Like, display all books in the category "Horror". I know its in the alley somewhere with the.Include() function but I hit a dead end and would need some pointers to figure this out - Thank you!

This is how my models look like:

Models/book.cs

class Book
{
    [Key]
    public int Id { get; set; }
    public string Title { get; set; }
    public string Author { get; set; }
    public int Price { get; set; }
    public int Amount { get; set; }
    public List<BookCategory> BookCategories { get; set; }
}

Models/BookCategory.cs

class BookCategory
{
    [Key]
    public int Id { get; set; }
    public string Name { get; set; }
    public List<Book> Books { get; set; }
}

I know so far I can include the category with the books

db.Books.Include("BookCategory");

But I don't know how to match the criteria to tell I only want to get the books with a certain category

Answer 1

If you want to filter by categories you can do something like this:

db.Books
  .Include("BookCategory")
  .Where(b => b.BookCategories.Any(c=>c.Name == "Horror"));

That should work, although I'm more accustomed to entity framework core now.