diff --git a/app/controllers/spree/api/stock_transfers_controller.rb b/app/controllers/spree/api/stock_transfers_controller.rb
index f57d501..2651c30 100644
--- a/app/controllers/spree/api/stock_transfers_controller.rb
+++ b/app/controllers/spree/api/stock_transfers_controller.rb
@@ -1,6 +1,8 @@
 module Spree
   module Api
     class StockTransfersController < Spree::Api::BaseController
+      helper 'solidus_stock_transfers/api'
+
       def receive
         authorize! :update, TransferItem
         @stock_transfer = Spree::StockTransfer.accessible_by(current_ability, :update).find_by!(number: params[:id])
diff --git a/app/controllers/spree/api/transfer_items_controller.rb b/app/controllers/spree/api/transfer_items_controller.rb
index af0f9e7..d2d9599 100644
--- a/app/controllers/spree/api/transfer_items_controller.rb
+++ b/app/controllers/spree/api/transfer_items_controller.rb
@@ -1,6 +1,8 @@
 module Spree
   module Api
     class TransferItemsController < Spree::Api::BaseController
+      helper 'solidus_stock_transfers/api'
+
       def create
         authorize! :create, TransferItem
         stock_transfer = Spree::StockTransfer.accessible_by(current_ability, :update).find_by(number: params[:stock_transfer_id])
@@ -37,6 +39,10 @@ def destroy
       def transfer_item_params
         params.require(:transfer_item).permit(permitted_transfer_item_attributes)
       end
+
+      def permitted_transfer_item_attributes
+        [:variant_id, :expected_quantity, :received_quantity]
+      end
     end
   end
 end
diff --git a/app/helpers/solidus_stock_transfers/api_helper.rb b/app/helpers/solidus_stock_transfers/api_helper.rb
new file mode 100644
index 0000000..017e7dd
--- /dev/null
+++ b/app/helpers/solidus_stock_transfers/api_helper.rb
@@ -0,0 +1,12 @@
+module SolidusStockTransfers
+  module ApiHelper
+    mattr_accessor :stock_transfer_attributes
+    @@stock_transfer_attributes = [:id, :number]
+
+    mattr_accessor :transfer_item_attributes
+    @@transfer_item_attributes = [:id, :expected_quantity, :received_quantity]
+
+    mattr_accessor :transfer_item_variant_attributes
+    @@transfer_item_variant_attributes = []
+  end
+end