It has bugged me for a long time that I could not access product information from bol.com the same way I could from Amazon.com. When bol.com released their public API some time ago, I still couldn’t. Not easily. So I wrote a Ruby library for the Bol.com API.
The bol.com API allows you to fetch detailed information for common products, such as books, DVDs and toys, search for products by keyword, or list bestsellers. The API is not too complex: it’s just a handful of endpoints, a couple of available query parameters and a request signature.
I built a wrapper around this API that exposes the available operations and
handles the difficult parts of request signing and XML parsing. All you, as the
developer, have to do is provide the access credentials. All operations give
you nice, clean Ruby objects back, such as a
You need to sign up for a developer account first. When your account has been approved, you can request an API key. The key has two parts – one public, one secret – that will be used by bol.com to make sure you really are who you say you are when you make a request.
Once you have both your access key and its secret, you can get started by installing the Ruby gem:
$ gem install bol
An example application
Let’s create a very simple Sinatra application to search the bol.com store (see
the completed app in one file). Create an application file
require 'sinatra' get '/' do erb :search end
Add a simple form view:
<form method="post" action="/search"> <label>Query: <input type="text" name="q"></label> <input type="submit"> </form>
Run the app to confirm everything works:
$ ruby -rubygems app.rb
When you browse to
http://localhost:2567 you can see the search page, but it
doesn’t do anything yet. Let’s add a search action:
post '/search' do @products =  erb :results end
And a view to display results:
<ol> <% @products.each do |product| %> <li><%= product.title %></li> <% end %> </ol>
We’ve added a
/search route that will somehow set an array of products, and
then render them to an ordered list on the page. Simple enough. Now to actually
search some products:
post '/search' do @products = Bol.search params[:q] erb :results end
Searching the bol.com website is as easy as
the app, and try it out. You will get an error, complaining that the gem is not
properly configured. We need to provide our access key and its secret, so they
can be used to sign our requests:
Bol.configure do |c| c.access_key = '123256789' c.secret = 'abcdefghi' end
When you restart the application, you should be able to search bol.com by keyword and get a list of titles back.
Showing product details
Let’s go one step further and add some product details. We’ll create a new route for that:
get '/product/:id' do @product = Bol::Product.find params[:id] erb :product end
We can use
Product#find to find a particular product on bol.com by its
internal ID. We’ll create a link to the detail page in our search results:
<ol> <% @products.each do |product| %> <li> <a href="/product/<%= product.id %>"> <%= product.title %> </a> </li> <% end %> </ol>
We also need a view for our new action:
<h1><%= @product.title %></h1> <dl> <% @product.attributes.each_pair do |k, v| %> <dt><%= k %></dt> <dd><pre><%= v %></pre></dd> <% end %> </dl>
Restart the app, perform a search and click on a result. You should see all
available product details. Note that there are several sizes of cover image
available, and that the
author attribute is an
Array – there can be more
than one, after all.
Scoping search results to categories
Now we want to limit our search results to a particular category of products. Bol.com products are extensively categorized and we can look up those categories and search in them. Let’s add a drop-down list of categories to search to our search form:
get '/' do @categories = Bol.categories erb :search end post '/search' do @products = Bol::Scope.new(params[:category_id]) .search params[:q] erb :results end
And in the view:
<form method="post" action="/search"> <select name="category_id"> <% @categories.each do |category| %> <option value="<%= category.id %>"> <%= category.name %> (<%= category.count %>) </option> <% end %> </select> <input type="text" name="q"> <input type="submit"> </form>
Once we’ve reloaded the application, we can choose a category to search in and
get results limited to that category. Categories are nested, so you can get
Bol::Scope.new(some_id).categories. And there are also
refinements, such as groupings by price or brand and other attributes, but
they work similarly to categories.
Then only referral links remain. It is a good idea to link to products on bol.com, so you can get a kickback on any sales resulting from the traffic you send over. This is not strictly a feature of the developer API, but it is so commonly used, I just threw it in here. You can simply ask a product for its referral URL, given a specific referral ID:
product = Bol.find(params[:id]) product.referral_link('my-site-id') # => "http://..."
This example application showcases the basics of the bol gem, but it includes some more:
- Ordering and limiting of number of results
- Automatic pagination
- Joining and subtracting categories and refinements to create complex scopes
- List popular or bestselling products
See the project README file for more information.
Example application and source code
That’s all you need to know to get started. You can see the entire example application in this gist. You can find the source for this Ruby gem on Github, where I also keep the API documentation and track issues. The gem is still in beta stage, so it can be field-tested before getting an actual stamp-of-approval by releasing a version 1.0. Try it out and do let me know if you make anything awesome with it!