Add /api/v1_alpha/accounts/:id/in_collections to list collections you are in (#38657)

app/controllers/api/v1_alpha/in_collections_controller.rb

@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+class Api::V1Alpha::InCollectionsController < Api::BaseController
+  include Authorization
+
+  DEFAULT_COLLECTIONS_LIMIT = 40
+
+  before_action :check_feature_enabled
+
+  before_action -> { authorize_if_got_token! :read, :'read:collections' }, only: [:index]
+
+  before_action :require_user!
+  before_action :set_account, only: [:index]
+  before_action :set_collections, only: [:index]
+
+  after_action :insert_pagination_headers, only: [:index]
+
+  after_action :verify_authorized
+
+  def index
+    cache_if_unauthenticated!
+    authorize @account, :index_featured_in_collections?
+
+    render json: @collections, each_serializer: REST::CollectionSerializer, adapter: :json
+  end
+
+  private
+
+  def set_account
+    @account = Account.find(params[:account_id])
+  end
+
+  def set_collections
+    @collections = @account.featured_in_collections
+      .with_tag
+      .offset(offset_param)
+      .limit(limit_param(DEFAULT_COLLECTIONS_LIMIT))
+  end
+
+  def check_feature_enabled
+    raise ActionController::RoutingError unless Mastodon::Feature.collections_enabled?
+  end
+
+  def next_path
+    return unless records_continue?
+
+    api_v1_alpha_account_in_collections_url(@account, pagination_params(offset: offset_param + limit_param(DEFAULT_COLLECTIONS_LIMIT)))
+  end
+
+  def prev_path
+    return if offset_param.zero?
+
+    api_v1_alpha_account_in_collections_url(@account, pagination_params(offset: offset_param - limit_param(DEFAULT_COLLECTIONS_LIMIT)))
+  end
+
+  def records_continue?
+    ((offset_param * limit_param(DEFAULT_COLLECTIONS_LIMIT)) + @collections.size) < @account.featured_in_collections.size
+  end
+
+  def offset_param
+    params[:offset].to_i
+  end
+end

app/models/concerns/account/associations.rb

@@ -18,6 +18,7 @@ module Account::Associations
         has_many :collections
         has_many :collection_items
         has_many :curated_collection_items, through: :collections, class_name: 'CollectionItem', source: :collection_items
+        has_many :featured_in_collections, through: :collection_items, class_name: 'Collection', source: :collection
         has_many :conversations, class_name: 'AccountConversation'
         has_many :custom_filters
         has_many :favourites

app/policies/account_policy.rb

@@ -72,4 +72,8 @@ class AccountPolicy < ApplicationPolicy
   def index_collections?
     current_account.nil? || !record.blocking_or_domain_blocking?(current_account)
   end
+
+  def index_featured_in_collections?
+    current_account.id == record.id
+  end
 end

config/routes/api.rb

@@ -8,6 +8,7 @@ namespace :api, format: false do
   namespace :v1_alpha do
     resources :accounts, only: [] do
       resources :collections, only: [:index]
+      resources :in_collections, only: [:index]
     end
 
     resources :async_refreshes, only: :show

spec/requests/api/v1_alpha/in_collections_spec.rb

@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe 'Api::V1Alpha::InCollections', feature: :collections do
+  include_context 'with API authentication', oauth_scopes: 'read:collections write:collections'
+
+  describe 'GET /api/v1_alpha/in_collections' do
+    subject do
+      get "/api/v1_alpha/accounts/#{account.id}/in_collections", headers: headers, params: params
+    end
+
+    let(:params) { {} }
+    let(:account) { user.account }
+
+    before { Fabricate.times(3, :collection_item, account: account) }
+
+    it 'returns all collections for the given account and http success' do
+      subject
+
+      expect(response).to have_http_status(200)
+      expect(response.parsed_body[:collections].size).to eq 3
+    end
+
+    context 'with limit param' do
+      let(:params) { { limit: '1' } }
+
+      it 'returns only a single result' do
+        subject
+
+        expect(response).to have_http_status(200)
+        expect(response.parsed_body[:collections].size).to eq 1
+
+        expect(response)
+          .to include_pagination_headers(
+            next: api_v1_alpha_account_in_collections_url(account, limit: 1, offset: 1)
+          )
+      end
+    end
+
+    context 'with limit and offset params' do
+      let(:params) { { limit: '1', offset: '1' } }
+
+      it 'returns the correct result and headers' do
+        subject
+
+        expect(response).to have_http_status(200)
+        expect(response.parsed_body[:collections].size).to eq 1
+
+        expect(response)
+          .to include_pagination_headers(
+            prev: api_v1_alpha_account_in_collections_url(account, limit: 1, offset: 0),
+            next: api_v1_alpha_account_in_collections_url(account, limit: 1, offset: 2)
+          )
+      end
+    end
+
+    context 'when requested account is different from current account' do
+      let(:account) { Fabricate(:account) }
+
+      it 'returns http forbidden' do
+        subject
+
+        expect(response)
+          .to have_http_status(403)
+      end
+    end
+  end
+end