Django Model Relationships (foreignkey) (manytomany)
===

I'm totally new to django, coming from a PHP perspective. I want to write a real basic application with four classes: Book, Ebook, Genre and price. Each Book and Ebook should have one genre and many prizes. In a SQL-DB I'd put a field in Book and Ebook referencing to a genre table by id and a new table called something like Book_prices which is linking Books and Ebooks to prices.

    table book_prices
    id | type   | price
    ---+--------+------ 
    1  |  book  | 3
    2  |  book  | 3 
    3  |  ebook | 1

    table book/ebook
    id | ... | genre_id
    ---+-----+---------
    1  |     | 5
    2  |     | 7
    3  |     | 9

Basically I want to add a list of prices and ONE genre for each Ebook and Book. How can I do this using the django model? I know of `model.ForeignKey()` which could be applied to each Book/Ebook referencing to a genre. But what about my prices? If I add a `ForeignKey()` to a price it can only reference to a Book OR Ebook. 

    class Book:
        name = models.CharField(max_length=100)
        pages = models.IntegerField()

    class Ebook:
        name = models.CharField(max_length=100)
        filesize = models.FloatField()

    class Genre:
        name = models.CharField(max_length=100)
        info = models.TextField()

    class Price:
        currency = models.CharField(max_length=4)
        amount = models.FloatField()
