This is a great book. I thought the first edition was good, but this is even better.
I’m still working my way through the pdf, but thought you might like to know about some minor errors etc.
Page 77 1st line
depot> ruby script/generate scaffold product \ > title:string description:text image_url:string
should be in red after depot>
Page 80-81 ..-add-price-to-product.rb
When I got to this I made some sort of mistake and got an error. After correcting the mistake I still received an error because the price column had been generated.
Therefore my suggestion is that you make a bit more of a point about reverting the migration on page 78. At the moment it’s just a note (7). I think a short paragraph explaining that if the reader gets an error it might be a good idea to reverse the migration and explain how to just reverse the last migration rather than going back to version 0.