Ruby ISBNdb is a simple, Ruby library that connects to's Web Service and API.
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Ruby ISBNdb

Ruby ISBNdb is a simple, Ruby library that connects to's Web Service and API. Ruby ISBNdb is written to mimic the ease of ActiveRecord and other ORM programs, without all the added hassles. It's still in beta phases, but it is almost fully functional for the basic search features of ISBNdb.

Version 1.x

ISBNdb 1.x.x has been deprecated!. You should upgrade to the new version as soon as possible. The old documentation is still available in the git history. There are significant changes in this new version, so please test appropriately.


To get started, install the gem:

gem install isbndb

Alternatively, you can add it to your Gemfile:

gem 'isbndb', '~> 2.0.0'

Basic Setup

To get started, you'll need to create a config/isbndb.yml file in your project root. It should look like this:

  - KEY_1
  - KEY_2

Where you list your access keys. This was in response to security holes in version 1.x where values were passed directly to the initializer.

Now you're ready to get started:

@query = ISBNdb::Query.find_book_by_title('Ruby')

ActiveRecord-like Usage

Another reason why you'll love Ruby ISBNdb is it's similarity to ActiveRecord. In fact, it's based on ActiveRecord, so it should look similar. It's best to lead by example, so here are a few ways to search for books, authors, etc:

ISBNdb::Query.find_books_by_title("Agile Development")
ISBNdb::Query.find_author_by_name("Seth Vargo")

Advanced Usage

Additionally, you can also use a more advanced syntax for complete control:

ISBNdb::Query.find(:collection => 'books', :where => { :isbn => '978-0-9776-1663-3' })
ISBNdb::Query.find(:collection => 'books', :where => { :author => 'Seth Vargo' }, :results => 'prices')

Options for :collection include books, subjects, categories, authors, and publishers.

If you are unfamiliar with some of these options, have a look at the ISBNdb API

Processing Results

A ResultSet is nothing more than an enhanced array of Result objects. The easiest way to process results from Ruby ISBNdb is most easily done using the .each method.

results = ISBNdb::Query.find_books_by_title("Agile Development")
results.each do |result|
  puts "title: #{result.title}"
  puts "isbn10: #{result.isbn}"
  puts "authors: #{result.authors_text}"

Note: calling a method on a Result object that is empty?, blank?, or nil? will always return nil. This was a calculated decision so that developers can do the following:

puts "title: #{result.title}" unless result.title.nil?


puts "title: #{result.title}" unless result.title.nil? || result.title.blank? || result.title.empty?

because API is generally inconsistent with respect to returning empty strings, whitespace characters, or nothing at all.

Note: XML-keys to method names are inversely mapped. CamelCased XML keys and attributes (like BookData or TitleLong) are converted to lowercase under_scored methods (like book_data or title_long). ALL XML keys and attributes are mapped in this way.


Pagination is based on the ResultSet object. The ResultSet object contains the methods go_to_page, next_page, and prev_page... Their function should not require too much explanation. Here's a basic example:

results = ISBNdb::Query.find_books_by_title("ruby")
results.next_page.each do |result|
  puts "title: #{result.title}"

A more realistic example - getting all books of a certain title:

results = ISBNdb::Query.find_books_by_title("ruby")
while results
  results.each do |result|
    puts "title: #{title}"

  results = results.next_page

It seems incredibly unlikely that a developer would ever use prev_page, but it's still there if you need it.

Because there may be cases where a developer may need a specific page, the go_to_page method also exists. Consider an example where you batch-process books into your own database (which is probably against Copyright laws, but you don't seem to care...):

results = ISBNdb::Query.find_books_by_title("ruby")
results = results.go_to_page(50) # where 50 is the page number you want

Note: go_to_page, next_page and prev_page return nil if the ResultSet is out of Result objects. If you try something like results.next_page.next_page, you could get a whiny nil. Think LinkedLists when working with go_to_page, next_page and prev_page.

BIGGER NOTE: go_to_page, next_page and prev_page BOTH make a subsequent call to the API, using up one of your 500 daily request limits. Please keep this in mind!

Advanced Key Management

As over version 2.0, all access key management has moved into the config/isbndb.yml file. ISBNdb will auto-rollover if you specify multiple keys.


Ruby ISBNdb now supports basic statistics (from the server):

ISBNdb::Query.keystats # => {:requests => 50, :granted => 49}
ISBNdb::Query.keystats[:granted] # => 49

Note: Ironically, this information also comes from the server, so it counts as a request...


Ruby ISBNdb could raise the following possible exceptions:


You will most likely encounter ISBNdb::AccessKeyError when you have reached your 500-request daily limit. ISBNdb::InvalidURIError usually occurs when using magic finder methods with typographical errors.

A Real-Life Example

Here is a real-life example of how to use Ruby ISBNdb. Imagine a Rails application that recommends books. You have written a model, Book, that has a variety of methods. One of those class methods, similar, returns a list of book isbn values that are similar to the current book. Here's how one may do that:

# books_controller.rb
def simliar
  @book = Book.find(params[:id])
  @query =['API-KEY-1', 'API-KEY-2'])
  @isbns = @book.similar # returns an array like [1234567890, 0987654321, 3729402827...]

  @isbns.each do |isbn|
      (@books ||= []) << ISBNdb::Query.find_book_by_isbn(isbn).first
    rescue ISBNdb::AccessKeyError
# similar.html.erb
<h1>The following books are recommeded for you:</h1>
<% @books.each do |book| %>
  <div class="book">
    <h2><%= book.title_long %></h2>
    <p><strong>authors</strong>: <%= book.authors_text %></p>
<% end %>


Build Status

Change Log

2012-6-17 - Released v2.0 2011-3-11 - Officially changed from ruby_isbndb to isbndb with special thanks to Terje Tjervaag for giving up the gem name :)


Special thanks to Terje Tjervaag ( for giving up the gem name 'isbndb'!

Special thanks to Lazlo ( for forwarding his project here!