Rails%203%20In%20Action

Pagination
If you click the 1 link or the Prev link, you’ll be taken back to the first page. All of
that functionality was given to you by the paginate method in your views and the page
call in your controller. You didn’t have to code any of this yourself, which is great.
Next, we’ll look at how you can add this same kind of pagination to the tickets API.
16.1.3 Paginating an API
You’ve easily set up pagination for your tickets on the interface that a user sees, to ease
the load on the database. However, for your tickets API you’re still returning all the
tickets for a project when they’re requested, and therefore you’ll run into the same
problems you solved in the previous section.
Your API is different though. You can’t provide a pagination link for the tickets
returned by an API. Instead, you’ll have to rely on people passing in a page number,
which you’ll then use to return that page of tickets.
To test this, you’re going to go into your API spec file for tickets at spec/api/v2/
tickets_spec.rb and add another test. This one should assert that when you pass in a
page parameter to your requests, you receive that page of tickets, rather than all of the
tickets or a different page.
In your API you’ll limit requests to 50 per response, but you may choose to set this
a little higher. 4 Therefore, you’ll create 100 tickets, which should give you enough
tickets to test that you can get the first and second pages of your API.
You’ll add another context to spec/api/v2/tickets_spec.rb to test pagination, using
the code shown in the following listing.
Listing 16.3 spec/api/v2/tickets_spec.rb
context "pagination" do
before do
100.times do
Factory(:ticket, :project => project, :user => @user)
end
end
it "gets the first page" do
get "/api/v2/projects/#{project.id}/tickets.json",
:token => token,
:page => 1
last_response.body.should eql(project.tickets.page(1).per(50).to_json)
end
it "gets the second page" do
get "/api/v2/projects/#{project.id}/tickets.json?page=2",
:token => token,
:page => 2
last_response.body.should eql(project.tickets.page(2).per(50).to_json)
end
end
4 200 seems to be a common number to use for API return objects per request.
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