- This route gives me an error, if you look in the params hash there is not key author_id; 
- To update the books authors, we need to first delete all of the currently associated authors and then reassign them using the same method that we used to create action; 

![image](https://f.cloud.github.com/assets/3854347/2455239/bcf7c808-aefa-11e3-9e2f-96781ba9fdd6.png)