Question

This is my first attempt at getting data back from an API, and getting the data to output to a view.

I want to put an ISBN number into a search form and get the data back for that particular book using http://isbndb.com/. This is what I have so far:

Controller:

require 'open-uri'
class BookController < ApplicationController
  def searchbook
  resp = open("http://isbndb.com/api/books.xml?access_key=#{'API KEY HERE'}&results=texts&index1=isbn&value1=#{params[:isbn]}")
  doc = Nokogiri.XML(resp.read)
  # ... process response here

 end
end

Form:

<%= form_tag({:controller => 'book', :action => 'searchbook'}, {:method => 'get'}) do |select| %>
<%= label_tag :isbn, "Enter ISBN Number" %>
<%= text_field_tag :isbn, params[:isbn] %>
<%= submit_tag "Search" %>
<% end %>

The XML to be returned

  <?xml version="1.0" encoding="UTF-8"?>
  <ISBNdb server_time="2005-07-29T03:02:22">
  <BookList total_results="1" page_size="10" page_number="1" shown_results="1">
  <BookData book_id="paul_laurence_dunbar" isbn="0766013502">
  <Title>Paul Laurence Dunbar</Title>
  <TitleLong>Paul Laurence Dunbar: portrait of a poet</TitleLong>
  <AuthorsText>Catherine Reef</AuthorsText>
  <PublisherText publisher_id="enslow_publishers">Berkeley Heights, NJ: Enslow Publishers, c2000.</PublisherText>
  <Summary>A biography of the poet who faced racism and devoted himself to depicting the black experience in America.</Summary>
  <Notes>"Works by Paul Laurence Dunbar": p. 113-114. Includes bibliographical references (p. 124) and index.</Notes>
  <UrlsText></UrlsText>
  <AwardsText></AwardsText>
  </BookData>
</BookList>
  </ISBNdb>

How do I process an XML request or what can I read to find out how?

Where can I view the data being returned in the console (if any)? I’m not even sure that this is doing anything as yet, however upon clicking “search” in my form I am taken to the searchbook action which is a blank page for now.

I may be a long way off from the whole answer but this is my first time doing this.

Answer 1

Parsing the XML is easy:

require 'nokogiri'

doc = Nokogiri::XML(<<EOT)
  <?xml version="1.0" encoding="UTF-8"?>
  <ISBNdb server_time="2005-07-29T03:02:22">
  <BookList total_results="1" page_size="10" page_number="1" shown_results="1">
  <BookData book_id="paul_laurence_dunbar" isbn="0766013502">
  <Title>Paul Laurence Dunbar</Title>
  <TitleLong>Paul Laurence Dunbar: portrait of a poet</TitleLong>
  <AuthorsText>Catherine Reef</AuthorsText>
  <PublisherText publisher_id="enslow_publishers">Berkeley Heights, NJ: Enslow Publishers, c2000.</PublisherText>
  <Summary>A biography of the poet who faced racism and devoted himself to depicting the black experience in America.</Summary>
  <Notes>"Works by Paul Laurence Dunbar": p. 113-114. Includes bibliographical references (p. 124) and index.</Notes>
  <UrlsText></UrlsText>
  <AwardsText></AwardsText>
  </BookData>
</BookList>
  </ISBNdb>
EOT

isbn_data = doc.search('BookData').map{ |book_data|

  hash = {}

  %w[ book_id isbn ].each do |p|
    hash[p.downcase.to_sym] = book_data[p]
  end

  %w[ Title TitleLong AuthorsText PublisherText Summary ].each do |t|
    hash[t.downcase.to_sym] = book_data.at(t).text
  end

  hash
}

pp isbn_data

Which outputs:

[{:book_id=>"paul_laurence_dunbar",
  :isbn=>"0766013502",
  :title=>"Paul Laurence Dunbar",
  :titlelong=>"Paul Laurence Dunbar: portrait of a poet",
  :authorstext=>"Catherine Reef",
  :publishertext=>"Berkeley Heights, NJ: Enslow Publishers, c2000.",
  :summary=>
   "A biography of the poet who faced racism and devoted himself to depicting the black experience in America."}]

This code was based on the idea you might be receiving multiple <BookData> blocks, so it returns an array of hashes. If you’ll only have one use:

hash = {}
book_data = doc.at('BookData')

%w[ book_id isbn ].each do |p|
  hash[p.downcase.to_sym] = book_data[p]
end

%w[ Title TitleLong AuthorsText PublisherText Summary ].each do |t|
  hash[t.downcase.to_sym] = book_data.at(t).text
end

pp hash

The output now looks like:

{:book_id=>"paul_laurence_dunbar",
 :isbn=>"0766013502",
 :title=>"Paul Laurence Dunbar",
 :titlelong=>"Paul Laurence Dunbar: portrait of a poet",
 :authorstext=>"Catherine Reef",
 :publishertext=>"Berkeley Heights, NJ: Enslow Publishers, c2000.",
 :summary=>
  "A biography of the poet who faced racism and devoted himself to depicting the black experience in America."}