Add validation if the organisation is not selected

app/controllers/merge_requests_controller.rb

@@ -64,7 +64,7 @@ private
   end
 
   def merge_request_organisation_params
-    { merge_request: @merge_request, merging_organisation: Organisation.find(params[:merge_request][:merging_organisation]) }
+    { merge_request: @merge_request, merging_organisation_id: params[:merge_request][:merging_organisation] }
   end
 
   def other_merging_organisaitions_params

app/models/merge_request_organisation.rb

@@ -1,8 +1,8 @@
 class MergeRequestOrganisation < ApplicationRecord
   belongs_to :merge_request, class_name: "MergeRequest"
   belongs_to :merging_organisation, class_name: "Organisation"
-  validates :merge_request_id, presence: { message: I18n.t("validations.organisation.stock_owner.blank") }
-  validates :merging_organisation_id, presence: { message: I18n.t("validations.organisation.managing_agent.blank") }
+  validates :merge_request_id, presence: { message: I18n.t("validations.merge_request.merge_request_id.blank") }
+  validates :merging_organisation_id, presence: { message: I18n.t("validations.merge_request.merging_organisation_id.blank") }
   validate :validate_merging_organisations
 
   has_paper_trail
@@ -10,18 +10,22 @@ class MergeRequestOrganisation < ApplicationRecord
 private
 
   def validate_merging_organisations
-    if MergeRequestOrganisation.where(merge_request_id:, merging_organisation:).count.positive?
+    if MergeRequestOrganisation.where(merge_request_id:, merging_organisation_id:).count.positive?
       errors.add(:merging_organisation, I18n.t("validations.merge_request.organisation_part_of_another_merge"))
     end
 
-    if MergeRequestOrganisation.where.not(merge_request_id:).where(merging_organisation_id: merging_organisation.id).count.positive?
+    if MergeRequestOrganisation.where.not(merge_request_id:).where(merging_organisation_id:).count.positive?
       errors.add(:merging_organisation, I18n.t("validations.merge_request.organisation_part_of_another_merge"))
       merge_request.errors.add(:merging_organisation, I18n.t("validations.merge_request.organisation_part_of_another_merge"))
     end
 
-    if MergeRequest.where(requesting_organisation: merging_organisation).count.positive?
+    if MergeRequest.where(requesting_organisation_id: merging_organisation_id).count.positive?
       errors.add(:merging_organisation, I18n.t("validations.merge_request.organisation_part_of_another_merge"))
       merge_request.errors.add(:merging_organisation, I18n.t("validations.merge_request.organisation_part_of_another_merge"))
     end
+
+    if merging_organisation_id.blank? || !Organisation.where(id: merging_organisation_id).exists?
+      merge_request.errors.add(:merging_organisation, I18n.t("validations.merge_request.organisation_not_selected"))
+    end
   end
 end

config/locales/en.yml

@@ -505,6 +505,7 @@ en:
         higher_than_expected: "Basic monthly rent must be between £0.00 and £9,999.00"
     merge_request:
       organisation_part_of_another_merge: "This organisation is part of another merge - select a different one"
+      organisation_not_selected: "Select an organisation from the search list"
 
   soft_validations:
     net_income:

spec/requests/merge_requests_controller_spec.rb

@@ -105,6 +105,36 @@ RSpec.describe MergeRequestsController, type: :request do
           expect(merge_request.merging_organisations.count).to eq(1)
         end
       end
+
+      context "when the user does not select an organisation" do
+        let(:params) { { merge_request: { merging_organisation: nil } } }
+
+        before do
+          patch "/merge-request/#{merge_request.id}/organisations", headers:, params:
+        end
+
+        it "does not update the merge request" do
+          merge_request.reload
+          expect(merge_request.merging_organisations.count).to eq(0)
+          expect(response).to have_http_status(:unprocessable_entity)
+          expect(page).to have_content(I18n.t("validations.merge_request.organisation_not_selected"))
+        end
+      end
+
+      context "when the user selects non existent id" do
+        let(:params) { { merge_request: { merging_organisation: "clearly_not_an_id" } } }
+
+        before do
+          patch "/merge-request/#{merge_request.id}/organisations", headers:, params:
+        end
+
+        it "does not update the merge request" do
+          merge_request.reload
+          expect(merge_request.merging_organisations.count).to eq(0)
+          expect(response).to have_http_status(:unprocessable_entity)
+          expect(page).to have_content(I18n.t("validations.merge_request.organisation_not_selected"))
+        end
+      end
     end
 
     describe "#remove_organisation" do