Errata for Agile Web Development with Rails, Third Edition

#35399: A common requirement that clients have is the ability to create URLs with hyphens rather than underscores (i.e., good looking and SEO optimized URLs). It would be nice if the Rails book included some insight on how best to achieve this. Permalink-Fu is one option. Is it the best option? Is it the only option?--Ricky Robinson

#35550: It would be great to see a section on the symbols used in rails with a description of what each is used for rather than an example.
e.g.
=> This symbol assigns ...
| Still don't know what this does
# Is this a way of converting a variable to a string?
{}
()
<
GSub with all those /\ things after it. I really haven't got a clue what this is or how it works. Can't find any info on this anywhere.

etc...

I have a number of times struggled to understand the syntax used whilst developing the Depot app (And still am in some cases) and when I have had to go and look up what a # is doing in the middle of a string for example I have struggled to find a reference that explains what it is and how it works.

I suppose a quick reference guide is what I'm looking for.

Thanks

James--James West

#35173: .. such as AJAX and RESTful
inter faces into their code: support is built in. (And if you’re not familar with
AJAX and REST inter faces, never fear —we’ll explain them later on.)

AJAX is not defined until page 125.
Restful is never defined. A little googling showed that Sam Ruby has written "Restful Web Services" and DHH wrote the forward for the book, so perhaps you know too much about Restful.

All I was looking for is a simple definition of Restful which I found at wikipedia (so maybe it isn't even right)

http en.wikipedia.org /wiki/ Representational_State_Transfer
Systems which follow Fielding’s REST principles are often referred to as “RESTful”.
--Jim Oser

#35251: I think you really should mention heroku.com as a way to develop an application without having to install everything. It's invaluable for learning and playing around without committing the time to getting a development environment set up.

Thanks for the awesome work!
Victor--Victor Marius Costan

#35013: Doesn't this command work for all operating systems, not just Mac OS X?
When would this step be necessary?
Couldn't one just do
rake db:migrate
to see if the database is configured?

The book states:
The following step is rarely necessary, but can be helpful if things continue to
go wrong. You can verify which version of sqlite3 your sqlite3-ruby inter face
is bound to by running the following either as a standalone program, or from
within irb, or from within ruby script/console.
require 'rubygems'
require 'sqlite3'
tempname = "test.sqlite#{3+rand}"
db = SQLite3::Database.new(tempname)
puts db.execute('select sqlite_version()')
db.close
File.unlink(tempname)

--Jim Oser

#35014: Instead of saying 10.4 and 10.5, and then latter referring to Tiger and Leopard, but not telling the reader that 10.4 is Tiger, and 10.5 is Leopard,

why not say 10.4.x and 10.5.x and for versions greater than 10.5.x look on your website for instructions?

That way, 3 mac releases from now, people won't be pondering what version was Tiger and what version was Leopard.

Also do these instructions imply equally well for the client version as well as the server version of 10.4.x and 10.5.x?--Jim Oser

#35015: Instead of saying 10.4 and 10.5, and then latter referring to Tiger and Leopard, but not telling the reader that 10.4 is Tiger, and 10.5 is Leopard,

why not say 10.4.x and 10.5.x and for versions greater than 10.5.x look on your website for instructions?

That way, 3 mac releases from now, people won't be pondering what version was Tiger and what version was Leopard.

Also do these instructions imply equally well for the client version as well as the server version of 10.4.x and 10.5.x?--Jim Oser

#35016: Was:
How to change the version of Rails that your
application is using is described in the sidebar on page 246.

To: How to change the version of Rails that your application is using is described on pages 245 to 247.

Comment:
freeze is mentioned on pages 41, 245, 246, and 247--Jim Oser

#35017: Since there are multiple authors, does it make sense to say

I write my Rails programs using a programmer’s editor

wiihout identifying who I is?

Perhaps one could say that Mac OS X users prefer TextMate, Xcode, Netbeans, vi, vim, and emacs.

Linux users use:

Window users use:

What does James Duncan Davidson use and why?--Jim Oser

#35931: In your whirlwind intro to ERb, the one thing that is missing is the comment syntax, <%# %> . Any programmer is going to want to add comments, but I (eventually) ran into a somewhat difficult to track down problem using what seemed the obvious solution to me: just putting a Ruby comment within <% %> (I think I was crashing the Ruby interpreter, but instead of getting an error message, the output just disappeared). Anyway, my suggestion is to mention that you can add comments with <%# %> and that <% # %> is considered an ERb syntax error.--James Nachbar

#33022: In the commandline examples: It is sometimes hard to distinguish what is to be typed and what is actually output from the commandline (especially with line wraps). I suggest to clear this that a different colour or bold is used for the command itself.--Egil Helland

#35354: in the command at the top of the page, the '>' for the second line confuses windows folks; I included the '>' in the command and the scaffold worked, just skipped creating the title attribute. Any chance that second prompt could look like 'depot>'; would be clear what is going on.--Ben Burbridge

#34436: In the first code listing on this page, it is difficult to distinguish between the user's command and the resulting output. Use of color and bolding, such as in the listing on the bottom of the page, should help this.
--Wyatt Greene

#32420: after adding the storecontroller, i received an error "No route matches "/login/index" with {:method=>:get}".

restarting mongrel cleared the problem.

might be providing this as a hint.
why do i need to restart mongrel is a secondary question that the authors might like to shed some light on.

i am running 2.0--mike h

#35001: Typesetting software is producing ligatures in the text - it's fine for the most part, but when I copy+pasted "find_products_for_sale" in the second line, the initial fi ligature caused some "issues" with the Ruby interpreter until I took a closer look at the code...relatively easy to spot if you're using a monospaced font (doesn't everyone?)

It's not a huge deal, but perhaps something that might be looked at?--Mark Glossop

#34930: Minor point: The styling of the page is such that the price of the last entry in the catalog (Pragmatic Version Control) doesn't clear the picture when the page is very wide (I am using 1680x1050). Adding a 'br clear="left"' tag fixes this, but adds unneeded space...--Phil MacGovern

#35728: We're working away at putting a button on the page, then instructed to put an action in that won't work - "So, that’s what we will have to fix next." Then the chapter ends!! We've been told that the page won't work and then given exercises! How much better to exclude the action & product id, viz <%= button_to "Add to Cart" %> & amend the text that followed to:
"Now our index page looks like Figure 7.3. Of course, if you push the button now nothing will happen because the button has no action associated with it. So, that’s what we will have to fix next."
The caption to figure 7.3 will be accurate as well!! The action can be entered in the following chapter.
Well it seems logical to me!--Steve Poole

#33976: The examples given for the number_to_currency helper method show corresponding example outputs. However, the chosen indicator, "=>", which directs readers attention to the ouput, is the same as one of the operands in the code. Essentially there are too many "=>" symbols. --Philip Ronald Dutton

#31958: It's possible to get a rather hard to find error if you leave off the parenthesis on the else clause in add_product (@items << CartItem.new(product) ). I left them off (was trying to further the habit of not using parenthesis all the time in Ruby) and this causes the following error:

<path>/rails/depot/app/models/cart.rb:13: syntax error, unexpected tIDENTIFIER, expecting kEND

I'm guessing that the issues is that without the parenthesis the binding gets messed up. Might be worth mentioning, as it took me quite a while to figure out what I had messed up... after the fix, the server might need to be restarted and the sessions cleared too (I had to do this the first time, but oddly enough, not after trying to replicate the error).--David Kapp

#31960: I got a 'uninitialized constant Cart::CartItem)' error, which took me quite a while to figure out. It was obviously a class loading problem, but I couldn't figure out why. Turns out I had put my CartItem class in a file called CartItem.rb, rather than cart_item.rb.

This is the first place that this error might occur in the book, so I think a callout might be a good idea.--Antony Blakey

#34936: Since later in the book (p118) you are swapping the order the calls to find_cart and Product.find (lines 2 and 3 of store_controller.rb), it is a little clearer to swap their order here, so that it is clearer on p118 what changes--Phil MacGovern

#34190: On pages 116-118, exceptions are said several (I noticed seven) times to be 'thrown' rather than 'raised'. Other languages use this terminology all the time, but the Pickaxe book makes a distinction between 'raising' exceptions (handled with 'rescue') and 'throwing' symbols (handled with 'catch').

I'm not sure if the two are interchangeable (eg you can rescue something that you throw, or catch something that you raise) but it would seem more consistent with the pickaxe book if these uses of 'throw' (or 'throws', 'thrown' etc) were changed to 'raise'.--Charlie O'Keefe

#34937: The method name of "redirect_to_index" is perhaps a little misleading; it doesn't take into account the flash. Perhaps call is "flash_and_redirect_to_index". A little long, I admit.--Phil MacGovern

#35051: in "<% for cart_item in @cart.items %>"
cart_item is different from the previously used
"<% for item in @cart.items %>"
It would avoid confusion to continue to use the previous "item" version instead of "cart_item". It is also more logic.--Giuseppe Caruso

#36038: one more thing that can prevent the AJAX from working: when I saved add_to_cart.js.rjs in UTF-8/DOS mode (UltraEdit on Windows), it wouldn't work. I had to save in in ASCII.--Phil MacGovern

#36036: Just a heads up, using Aptana 1.2 the fade code doesn't seem to play nice. It works in IE 7 and Firefox 3.0.4 fine outside the IDE, but inside it throws an error. When the store page is first loaded IE in the integrated preview inside Aptana give a runtime error with Line: 335 / Error: 'Autocompleter.Base.prototype.getTokenBounds' is null or not an object.

If you hit No, the page loads fine, however the new fade gives an RJS error: [object Error] when you try and add an item to the cart. Again, this doesn't occur outside Aptana, but in the event anyone is using it I figured I'd report it.--Josh

#34624: The last sentence, in which you state that "making our application work regardless of whether JavaScript is enabled takes just a two line of code change in the add_to_cart action," is awkward. Perhaps the following would be better: ". . . enabled requires just two lines of code in the add_to_cart action."--Jeff Springman

#34673: "As it stands, that’s not particularly interesting: because it’s a new model, all the fields will be empty. However, consider the general case. Maybe we want to edit an existing model."

I think you're using the word "model" where the word "order" (an instance of the order model) would be more clear. (Similarly, in the next sentence you say "tried to enter an order", and I think that's right.) Suggest:

"As it stands, that’s not particularly interesting: because it’s a new order, all the fields in the model will be empty. However, consider the general case. Maybe we want to edit an existing order."--Brent J. Nordquist

#35841: The CSS breaks a bit here. Only inputs get the margin, and selects and text areas aren't inputs (for styling anyway). It should rightly be:

.depot-form input, .depot-form select, .depot-form textarea {
margin-left: 0.5em;
}--Robert Kosek

#35238: In footnote 5, the text "because an application _can’t_ assume" should be "because an application _shouldn’t_ assume".

We all know of applications that _do_ assume, so "can't" isn't correct: "shouldn't" is more appropriate.--Mark Glossop

#35239: Directing readers to follow ("On line 3...", "on line 5...") a code snippet that is interrupted by 2 footnotes, a page break and a "Joe Asks..."? Probably not the smartest layout...

[If it wasn't obvious, my suggestion is to arrange the text such that the code isn't broken up at all.]--Mark Glossop

#35041: In the explanation of why we use 'self.salt = ....' it says: "... Without the self., Ruby would
have thought we were assigning to a local variable, and our code would have no effect. "
That is pretty clear, what is NOT so clear is, why is the writer not using '@salt = ...'? After looking at the example several times I am still not sure whether those two are equivalant in this case.--Reuben Sivan

#34206: Adding a user did not work for me until I restarted my server. I don't know why. Is RESTful routing not correctly generated until the server restarts? This is a very confusing issue. --David Lyon

#36123: seem to be switching back and forth between 'redirect_to(:action=>:index)' (p165) and 'redirect_to(:action=>"index")' (p168).

Be consistent. (or need to explain that they need the same thing)--Phil MacGovern

#33034: When I got to this page and looked at the nice login form in figure 11.1, then compared it to the completely plain one in my application, I realized that we never made an admin layout. Maybe that should have been obvious, but I missed it. Just copying the users layout and editing it seemed to do the trick.--Shane Walker

#33965: I had to do a "mongrel_rails restart" after adding admin controller. Was getting "No controller responded to.. etc.." when trying to view /admin. Guessing there's some caching problem with mongrel -- might want to add a note that a restart may be required.

#34004: After rake:db:sessions:clear when using MySQL the app breaks.

Mysql::Error: Lost connection to MySQL server during query: SELECT * FROM `sessions`

It's fixed by restarting the app server.--Rory OConnell

#35286: Why don't you remove app/views/layouts/order.html.erb like as product.html.erb and user.html.erb file?

You generated order by call scaffold, it made app/views/layouts/order.html.erb file automatically. When the layout file exist, he nice global layout isn't applied to screen even I click order link on side panel.

I use rails 2.1.1 in Ubuntu 8.10.

thanks.--JinYoung,Heo

#34334: I found the placement of the code fragment (fig 13.1) at the top of this page (@@default_error_messages = ...) confusing, especially when it follows the sentence "The complete file now looks like this." I think the book would be clearer if it was moved closer to where it is relevant, or better separated from other pieces of code.

#36041: [Separate] Suggestion: move the DSL content to the _end_ of section 13.4, rather than smack-bang in the middle where it effectively interrupts the flow of the content.--Mark Glossop

#35840: In the demo that starts off section 15.1, you might want to add

require 'activesupport'

to the top of code block so that this could be run using the irb shell. This is a given for some users, but may not be for rails beginners. Thanks.--Shilo

#35390: My ruby version is 1.8.7 (pathlevel 72) and it already has Symbol#to_proc!!. Of course, rails 2.1.1's Symbol class still redefine to_proc method, but it can raise confusing to reader if there isn't any mention about it. :-)--JinYoung,Heo

#34730: I found the order by example a little confusing, simply because it was in the context of product orders. Here's the code:
orders = Order.find(:all,
:conditions => "name = 'Dave'" ,
:order => "pay_type, shipped_at DESC" )

There are four different uses of the word "order", and it took me a moment to think it through. This might mean it's a good example because it forces the reader to think, but I thought I'd point it out just in case it wasn't intentional.--David Christiansen