Application error - SQL_AUTO_IS_NULL

I have a simple controller (browse) that uses a "books" action to
display a list of books (stored in a mysql db) and a "book_details"
action to display the details of a particular book (according to the
book's mysql id). The book_details action is accessed via a link from
the books action via the following snippet:

<a href=<%= "/browse/book_details/#{_bookID}" %> class="text11"
style="text-decoration:none">
<%= _title %>
</a>

where _title is properly set to the book's title and _bookID is the
mysql id of the book. I've verified that _title and _bookID are set
properly. Equivalently, I've also used the following snippet instead
of the above:

<%= link_to(_title,
{ :controller => "browse",
  :action => "book_details",
  :id => _bookID
}) %>

In both of the above cases, I'm using the default route: map.connect
':controller/:action/:id'
In my test environment (Windows XP, Instant Rails, Aptana IDE)
everything works just fine. When I try to run this in production mode
on the ISP's site (asmallorange.com - CentOS) the books action works
just fine but the book_details action results in the extremely
descriptive :expressionless: error message displayed as a webpage:

Application error
Rails application failed to start properly

For the life of me, I don't see what I'm doing wrong. On the ISP site,
I set the log level to debug and compared the log files from both the
test (Windows XP) and production (CentOS) environments. The only
difference I could find is that in the CentOS production log, I see a
SQL_AUTO_IS_NULL message in the log file. I can't figure out what this
means and am not sure how relevant it is. Any suggestions are
appreciated. Should I do something special with the routes?

Below are the two log files.

I have a simple controller (browse) that uses a "books" action to
display a list of books (stored in a mysql db) and a "book_details"

Do your books have more than one set of details, per book?

action to display the details of a particular book (according to the
book's mysql id). The book_details action is accessed via a link from
the books action via the following snippet:

<a href=<%= "/browse/book_details/#{_bookID}" %> class="text11"
style="text-decoration:none">
<%= _title %>
</a>

where _title is properly set to the book's title and _bookID is the
mysql id of the book. I've verified that _title and _bookID are set
properly. Equivalently, I've also used the following snippet instead
of the above:

<%= link_to(_title,
{ :controller => "browse",
        :action => "book_details",
        :id => _bookID
}) %>

Why are you using all the underscore-prefixed _vars ? What purpose do
they serve?

When you get an ActiveRecord book object from the database does it not
contain the book id? Why not reference it as is? @book.id or
whatever.

In both of the above cases, I'm using the default route: map.connect
':controller/:action/:id'
In my test environment (Windows XP, Instant Rails, Aptana IDE)
everything works just fine. When I try to run this in production mode
on the ISP's site (asmallorange.com - CentOS) the books action works
just fine but the book_details action results in the extremely
descriptive :expressionless: error message displayed as a webpage:

Application error
Rails application failed to start properly

In production it's wise to not display visible errors on the screen,
which is exactly what Rails does by default.

For the life of me, I don't see what I'm doing wrong. On the ISP site,
I set the log level to debug and compared the log files from both the
test (Windows XP) and production (CentOS) environments. The only
difference I could find is that in the CentOS production log, I see a
SQL_AUTO_IS_NULL message in the log file. I can't figure out what this
means and am not sure how relevant it is.

Google returned this as the first result when I searched:

http://dev.mysql.com/doc/refman/5.0/en/set-option.html

SQL_AUTO_IS_NULL = {0 | 1}

If set to 1 (the default), you can find the last inserted row for a
table that contains an AUTO_INCREMENT column by using the following
construct:

WHERE auto_increment_column IS NULL

Any suggestions are
appreciated. Should I do something special with the routes?

If you app requires it, yes. I see nothing in your post to warrant
any changes to the default however.

Below are the two log files.

====================
test environment log file that works (Windows XP)

Processing BrowseController#book_details (for 127.0.0.1 at 2008-01-21
14:20:22)
[GET]
  Session ID: e49a3adf336e845be40dc8573f2b32c9
  Parameters: {"action"=>"book_details", "id"=>"1",
"controller"=>"browse"}
  ←[4;35;1mBook Columns (0.000000)←[0m ←[0mSHOW FIELDS FROM
books←[0m
  ←[4;36;1mBook Load (0.000000)←[0m ←[0;1mSELECT * FROM books WHERE
(books.`id
` = 1) ←[0m
Rendering within layouts/browse
Rendering browse/book_details
Completed in 0.01600 (62 reqs/sec) | Rendering: 0.00000 (0%) | DB:
0.00000 (0%)
> 200 OK [http://localhost/browse/book_details/1]

====================
production environment log file that doesn't work (CentOS)

# Logfile created on Mon Jan 21 14:29:06 -0500 2008 by /

Processing BrowseController#book_details (for 69.143.120.176 at
2008-01-21 14:29
:06) [GET]
  Session ID: ded95bf9e5a23822f854e9ba58d69d6e
  Parameters: {"action"=>"book_details", "id"=>"1",
"controller"=>"browse"}
  ^[[4;36;1mSQL (0.000086)^[[0m ^[[0;1mSET SQL_AUTO_IS_NULL=0^[[0m
  ^[[4;35;1mBook Columns (0.001176)^[[0m ^[[0mSHOW FIELDS FROM
books^[[0m
  ^[[4;36;1mBook Load (0.000065)^[[0m ^[[0;1mSELECT * FROM books
WHERE (books.
`id` = 1) ^[[0m
Rendering within layouts/browse
Rendering browse/book_details
Completed in 0.06461 (15 reqs/sec) | Rendering: 0.01440 (22%) | DB:
0.00133 (2%)
> 200 OK [http://www.epps-alford.com/browse/book_details/1]

I think you will find your problem somewhere in your _var (re)assignments.

Greg,

Thanks for your feedback.

I think you will find your problem somewhere in your _var (re)assignments.

My style of variable name derives from coding in other languages (Java/
C++). I didn't think that was related but switched the variables
around just in case per your suggestion. Unfortunately that didn't
help.

It turns out that the problem was unrelated to variable names or the
SQL_AUTO_IS_NULL setting. The problem was due to a puts statement in
my controller. The following action was defined in my controller:

  def book_details
    puts "ID equals #{params[:id]}"
    @book = Book.find(params[:id])
    @pageTitle = "Epps-Alford Bookstore"
  end

This caused the mysterious error. Things worked fine on my development
machine (Windows XP, InstantRails) but crapped out in the production
environment (CentOS). By removing the puts method, the action started
working in the production environment on Linux/CentOS.

Thanks!!!