Paginate boards JSON

app/controllers/boards_controller.rb

@@ -6,8 +6,8 @@ class BoardsController < ApplicationController
 
   def index
     if request.format.json?
-      @boards = Current.user.boards.ordered_by_recently_accessed
-      fresh_when @boards
+      set_page_and_extract_portion_from Current.user.boards.ordered_by_recently_accessed
+      fresh_when etag: @page.records
     else
       set_page_and_extract_portion_from Current.user.boards
     end

app/views/boards/index.json.jbuilder

@@ -1 +1 @@
-json.array!(@boards, partial: "boards/board", as: :board)
+json.array! @page.records, partial: "boards/board", as: :board

test/controllers/boards_controller_test.rb

@@ -207,7 +207,7 @@ class BoardsControllerTest < ActionDispatch::IntegrationTest
     assert_equal users(:kevin).boards.count, @response.parsed_body.count
   end
 
-  test "index as JSON includes all boards ordered by recently accessed" do
+  test "index as JSON paginates and preserves recently-accessed order" do
     account = accounts("37s")
     kevin = users(:kevin)
     baseline_accessed_at = 3.days.ago.change(usec: 0)
@@ -216,7 +216,7 @@ class BoardsControllerTest < ActionDispatch::IntegrationTest
       access.update!(accessed_at: baseline_accessed_at + index.seconds)
     end
 
-    35.times do |index|
+    200.times do |index|
       board = Board.create!(
         name: "Recent board #{index}",
         creator: kevin,
@@ -226,14 +226,22 @@ class BoardsControllerTest < ActionDispatch::IntegrationTest
       board.access_for(kevin).update!(accessed_at: baseline_accessed_at + (index + 1).minutes)
     end
 
-    get boards_path, as: :json
-
-    assert_response :success
-
     expected_ids = kevin.boards.ordered_by_recently_accessed.pluck(:id)
-    actual_ids = @response.parsed_body.map { |board| board["id"] }
+    actual_ids = []
+    next_page = boards_path(format: :json)
+    page_count = 0
+
+    while next_page
+      get next_page, as: :json
+      assert_response :success
+
+      page_count += 1
+      actual_ids.concat(@response.parsed_body.map { |board| board["id"] })
+      next_page = next_page_from_link_header(@response.headers["Link"])
+    end
 
     assert_equal expected_ids, actual_ids
+    assert_operator page_count, :>, 1
   end
 
   test "show as JSON" do
@@ -269,4 +277,10 @@ class BoardsControllerTest < ActionDispatch::IntegrationTest
 
     assert_response :no_content
   end
+
+  private
+    def next_page_from_link_header(link_header)
+      url = link_header&.match(/<([^>]+)>;\s*rel="next"/)&.captures&.first
+      URI.parse(url).request_uri if url
+    end
 end