Question

So my data model has something like this: Author.Books
where a single Author can have multiple Books associated with it.

I can retrieve an Author with this route: /api/Authors/4
… and I can get a list of all books like: /api/Books, or a single book like /api/Books/8

So how would I get all the books for a single Author? something like: /Authors/4/Books
I don’t know what needs to happen to enable the “/Books” part of that example. Do I modify the BooksController (and how)? Or the AuthorsController? Or… ?

Answer 1

You should seriously consider using the Powerful Odata translation capabilities of the web Api. It allows you to build rich queries directly in the querystring that are translated to a Linq expression. This is how I would solve your problem.

First, ensure that your book model has an AuthorId Property:

public class Book
{
    public string Title{get; set;}
    public int AuthorId{get; set;}
}

Next, create a books controller and expose the Get method that returns an IQueryable:

public class BooksController : ApiController
{
    public IQueryable<Books> Get()
    {
        var books = new List
        {
            new Book{Title = "Book 1", AuthorId = 1},
            new Book{Title = "Book 2", AuthorId = 2},
        };

        return books.AsQueryable();

    }
}

Finally, to query a book by a particular author your URI will look as such:

/books?$filter=AuthorId eq 2