From 0c8eef2a3667655dcdc0945479abf0d49cfca784 Mon Sep 17 00:00:00 2001
From: Morgan Roderick <morgan@roderick.dk>
Date: Sat, 8 Aug 2026 17:40:19 +0200
Subject: [PATCH] fix: events coach/student 500 when member already has an
 invitation

`Invitation.create_or_find_by` in `find_invitation_and_redirect_to_event`
returns an unsaved record (id/token nil) when the member already has an
invitation for the event+role with attending nil, because the uniqueness
validation fails but create_or_find_by only rescues RecordNotUnique. The
subsequent `redirect_to event_invitation_path` then raises a
UrlGenerationError for a missing token.

Fall back to the existing persisted invitation when create_or_find_by
returns an unpersisted record. Same fix as #2791 applied to the events path.

Fixes #2794
---
 app/controllers/events_controller.rb       |  5 +-
 spec/controllers/events_controller_spec.rb | 72 ++++++++++++++++++++++
 2 files changed, 75 insertions(+), 2 deletions(-)

diff --git a/app/controllers/events_controller.rb b/app/controllers/events_controller.rb
index 6506354de..543c0d7c7 100644
--- a/app/controllers/events_controller.rb
+++ b/app/controllers/events_controller.rb
@@ -63,8 +63,9 @@ def latest_model_updated
 
   def find_invitation_and_redirect_to_event(role)
     set_event
-    @invitation = Invitation.create_or_find_by(event: @event, member: current_user, role: role)
-    redirect_to event_invitation_path(@event, @invitation)
+    invitation = Invitation.create_or_find_by(event: @event, member: current_user, role: role)
+    invitation = Invitation.find_by(event: @event, member: current_user, role: role) unless invitation.persisted?
+    redirect_to event_invitation_path(@event, invitation)
   end
 
   def set_event
diff --git a/spec/controllers/events_controller_spec.rb b/spec/controllers/events_controller_spec.rb
index 0438ad0db..29f639fb1 100644
--- a/spec/controllers/events_controller_spec.rb
+++ b/spec/controllers/events_controller_spec.rb
@@ -15,6 +15,78 @@
     end
   end
 
+  describe 'GET #student' do
+    let(:member) { Fabricate(:member) }
+    let(:event) { Fabricate(:event) }
+
+    before { login(member) }
+
+    context 'when the member already has an invitation for the event and role with attending nil' do
+      let!(:invitation) do
+        Fabricate(:invitation, event: event, member: member, role: 'Student', attending: nil)
+      end
+
+      it 'redirects to the existing invitation page' do
+        get :student, params: { event_id: event.slug }
+
+        expect(response).to redirect_to(event_invitation_path(event, invitation))
+      end
+
+      it 'does not create a new invitation' do
+        expect do
+          get :student, params: { event_id: event.slug }
+        end.not_to change(Invitation, :count)
+      end
+    end
+
+    context 'when the member does not have an invitation for the event and role' do
+      it 'creates a new invitation and redirects' do
+        expect do
+          get :student, params: { event_id: event.slug }
+        end.to change(Invitation, :count).by(1)
+
+        invitation = Invitation.last
+        expect(response).to redirect_to(event_invitation_path(event, invitation))
+      end
+    end
+  end
+
+  describe 'GET #coach' do
+    let(:member) { Fabricate(:member) }
+    let(:event) { Fabricate(:event) }
+
+    before { login(member) }
+
+    context 'when the member already has a coach invitation for the event with attending nil' do
+      let!(:invitation) do
+        Fabricate(:coach_invitation, event: event, member: member, attending: nil)
+      end
+
+      it 'redirects to the existing invitation page' do
+        get :coach, params: { event_id: event.slug }
+
+        expect(response).to redirect_to(event_invitation_path(event, invitation))
+      end
+
+      it 'does not create a new invitation' do
+        expect do
+          get :coach, params: { event_id: event.slug }
+        end.not_to change(Invitation, :count)
+      end
+    end
+
+    context 'when the member does not have a coach invitation for the event' do
+      it 'creates a new coach invitation and redirects' do
+        expect do
+          get :coach, params: { event_id: event.slug }
+        end.to change(Invitation, :count).by(1)
+
+        invitation = Invitation.last
+        expect(response).to redirect_to(event_invitation_path(event, invitation))
+      end
+    end
+  end
+
   describe '#past' do
     before { Fabricate(:event, date_and_time: 2.weeks.ago) }