API: Add route for fetching a user's followed tags (#9108)

* Add route for fetching a user's followed tags

* Move followed tags route to FollowsController instead of TagsController and add JSON view

* Add missing new line

* Change the dots for our linter

Co-authored-by: rhymes <rhymes@hey.com>
Co-authored-by: Molly Struve <mollylbs@gmail.com>

app/controllers/api/v0/follows_controller.rb

@@ -1,7 +1,7 @@
 module Api
   module V0
     class FollowsController < ApiController
-      before_action :authenticate_with_api_key_or_current_user!, only: [:create]
+      before_action :authenticate_with_api_key_or_current_user!
 
       def create
         user_ids = params[:users].map { |h| h["id"] }
@@ -10,6 +10,13 @@ module Api
         end
         render json: { outcome: "followed #{user_ids.count} users" }
       end
+
+      def tags
+        @follows = @user.follows_by_type("ActsAsTaggableOn::Tag")
+          .select(%i[id followable_id followable_type points])
+          .includes(:followable)
+          .order(points: :desc)
+      end
     end
   end
 end

app/views/api/v0/follows/tags.json.jbuilder

@@ -0,0 +1,4 @@
+json.array! @follows.each do |follow|
+  json.extract!(follow.followable, :id, :name)
+  json.extract!(follow, :points)
+end

config/routes.rb

@@ -162,7 +162,11 @@ Rails.application.routes.draw do
           end
         end
         resources :tags, only: [:index]
-        resources :follows, only: [:create]
+        resources :follows, only: [:create] do
+          collection do
+            get :tags
+          end
+        end
         namespace :followers do
           get :users
           get :organizations

spec/requests/api/v0/follows_spec.rb

@@ -30,4 +30,33 @@ RSpec.describe "Api::V0::FollowsController", type: :request do
       end
     end
   end
+
+  describe "GET /api/follows/tags" do
+    it "returns unauthorized if user is not signed in" do
+      get "/api/follows/tags"
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    context "when user is authorized" do
+      let!(:user) { create(:user) }
+      let(:tag1) { create(:tag) }
+      let(:tag2) { create(:tag) }
+      let(:tag3) { create(:tag) }
+
+      let(:tag1_json) { { id: tag1.id, name: tag1.name, points: 1.0 } }
+      let(:tag2_json) { { id: tag2.id, name: tag2.name, points: 1.0 } }
+
+      before do
+        sign_in user
+        [tag1, tag2].each { |tag| user.follow(tag) }
+      end
+
+      it "returns only the tags the user follows", aggregate_failures: true do
+        get "/api/follows/tags"
+        body = JSON.parse(response.body, symbolize_names: true)
+        expect(body).to include(tag1_json)
+        expect(body).to include(tag2_json)
+      end
+    end
+  end
 end