ConstantContact::Util::Config.configure do |config|
      config[:auth][:api_key] = 'foobar'
      config[:auth][:api_secret] = 'foobar'
    end

B. Sinatra example :


1. Install the gem :

        gem install constantcontact

2. Add the following code in myapp.rb (just an example):
        require 'active_support'
        require 'constantcontact'

        get '/my_url' do
            @oauth = ConstantContact::Auth::OAuth2.new(
                :api_key => 'your api key',
                :api_secret => 'your secret key',
                :redirect_url => 'your redirect url'
            )

            @error = params[:error]
            @user = params[:username]
            @code = params[:code]

            if @code
                response = @oauth.get_access_token(@code)
                if response
                    token = response['access_token']
                    cc = ConstantContact::Api.new('your api key')
                    @contacts = cc.get_contacts(token)
                end
            end

            erb :my_view
        end


    Note: 'your redirect url' is the URL of the route you just created ( get '/my_url' ).

4. Create a my_view.rhtml (or my_view.erb) with the following code:

        <% if @error %>
            <p>
                <%=@error%>
            </p>
        <% end %>

        <% if @code %>
            <% if @contacts %>
                <% for contact in @contacts %>
                    <p>
                        Contact name: <%= contact.first_name + contact.last_name %>
                    </p>
                <% end %>
            <% end %>
        <% else %>
            <a href="<%[email protected]_authorization_url%>">Click to authorize</a>
        <% end %>

5. The first time you access the action in browser you should see the "Click to authorize" link.
Follow the link, go through all the Constant Contact steps required 
and then you will be redirected back to your action and you should see the list of contacts.