Downloaded and unzipped rails3-code contains multiple versions of depot application. Based on page 695 comments I assumed that depot_s is the right version. However the package contains even later version depot_t. Besides, appendix C.1 claims to be “the full depot application” but a number of source files are missing in the book while they are present in the download. Furthermore the code of line_items_controller.rb presented on page 637 comes from depot_t but this file is not listed in C.1 at all.
Sorry about the confusion.
depot_t contains the ActiveResource changes (chapter 26).
I’ve tracked down which files aren’t included in Appendix C.1, and I’ll make sure that they are included in the next PDF. I’ll also update Appendix C.1 to reference depot_t.