I have followed the book chapter by chapter so far and have now reached chapter 12, which in the preface to the third edition is marked as not yet working with Rails 2.1. The next chapter is marked as “untouched” and I am wondering if I can skip ahead to that one or if for the sake of my currently still fragile understanding of Rails I am better to just skip these two chapters completely until they have been updated? Chapters 14 to 20 have been marked as updated to Rails 2.1, so as a Rails novice, do I stand a chance of understanding these chapters without completing the Depot application?
Those two chapters are not essential for you to proceed with the rest of the book, and can be picked up after the next beta is released.
I have made a first pass at those chapters (unreleased) and can answer questions if you decide to press on. The places in the existing text where you are most likely to get stuck is that (in chapter 12) response.xml isn’t automatic anymore, and must be specified explicitly, and (in chapter 13) what was previously the login controller in the previous edition is now in an admin controller.