testing postcode missing

app/controllers/locations_controller.rb

@@ -44,7 +44,7 @@ private
 
   def location_params
     required_params = params.require(:location).permit(:postcode, :name, :total_units, :type_of_unit, :wheelchair_adaptation, :add_another_location).merge(scheme_id: @scheme.id)
-    required_params[:postcode] = required_params[:postcode].gsub(" ", "").encode("ASCII", "UTF-8", invalid: :replace, undef: :replace, replace: "")
+    required_params[:postcode] = required_params[:postcode].gsub(" ", "").encode("ASCII", "UTF-8", invalid: :replace, undef: :replace, replace: "") if required_params[:postcode]
     required_params
   end
 end

app/models/location.rb

@@ -36,7 +36,7 @@ class Location < ApplicationRecord
 private
 
   def validate_postcode
-    unless postcode.match(Validations::PropertyValidations::POSTCODE_REGEXP)
+    if postcode.nil? || !postcode&.match(Validations::PropertyValidations::POSTCODE_REGEXP)
       error_message = I18n.t("validations.postcode")
       errors.add :postcode, error_message
     end

spec/requests/locations_controller_spec.rb

@@ -103,6 +103,16 @@ RSpec.describe LocationsController, type: :request do
         expect(Location.last.wheelchair_adaptation).to eq("No")
       end
 
+      context "when required organisation id param is missing" do
+        let(:params) { { location: { name: "Test", total_units: "5", type_of_unit: "Bungalow", wheelchair_adaptation: "No", add_another_location: "No" } } }
+
+        it "displays the new page with an error message" do
+          post "/schemes/#{scheme.id}/location/create", params: params
+          expect(response).to have_http_status(:unprocessable_entity)
+          expect(page).to have_content(I18n.t("validations.postcode"))
+        end
+      end
+
       context "when do you want to add another location is selected as yes" do
         let(:params) { { location: { name: "Test", total_units: "5", type_of_unit: "Bungalow", wheelchair_adaptation: "No", add_another_location: "Yes", postcode: "ZZ1 1ZZ" } } }