Cache consent status in database (#3263)

This introduces a new model, `Patient::ConsentStatus`, which stores the
status of a patient-programme pair in the database so it can queried and
rendered quickly. Locally, I'm seeing the consent tab on sessions with
50,000 patients load almost instantly even when filtering on statuses.
The session overview page has a slight improvement, but that will only
load quickly once the other statuses are cached.

I've decided not to implement a state machine as had been previously
discussed, but this could be built on top of this change to enhancement
the functionality. For now, this effectively caches the existing logic
that runs on the fly to the database.

I've also decided not to implement this using Rails callbacks and
instead be explicit where the status is refreshed. This allows us to
optimise for bulk refreshes, as is necessary when adding new programmes
to sessions, running the seeds, or generally updating the status of an
entire session.

This is proposed as an alternative to #3262 for consent statuses, we'd
need to apply the same functionality to triage, programmes, sessions and
next actions. If we're happy with this approach, we can migrate the
statuses one by one to avoid a big bang approach unlike #3262.

Author: thomasleese

app/components/app_consent_component.html.erb

@@ -1,6 +1,6 @@
 <%= render AppConsentStatusComponent.new(patient_session:, programme:) %>
 
-<% if patient.consent_outcome.no_response?(programme) %>
+<% if consent_status.no_response? %>
   <% if latest_consent_request %>
     <p class="nhsuk-body">
       No-one responded to our requests for consent.

app/components/app_consent_component.rb

@@ -14,7 +14,11 @@ def initialize(patient_session:, programme:)
 
   def consents
     @consents ||=
-      patient.consent_outcome.all[programme].sort_by(&:created_at).reverse
+      patient
+        .consents
+        .where(programme:)
+        .includes(:consent_form, :parent)
+        .order(created_at: :desc)
   end
 
   def latest_consent_request
@@ -27,10 +31,13 @@ def latest_consent_request
         .first
   end
 
+  def consent_status
+    @consent_status ||= patient.consent_status(programme:)
+  end
+
   def can_send_consent_request?
-    patient.consent_outcome.no_response?(programme) &&
-      patient.send_notifications? && session.open_for_consent? &&
-      patient.parents.any?
+    consent_status.no_response? && patient.send_notifications? &&
+      session.open_for_consent? && patient.parents.any?
   end
 
   def status_colour(consent)

app/components/app_consent_status_component.rb

@@ -9,12 +9,12 @@ def initialize(patient_session:, programme:)
   end
 
   def call
-    case patient.consent_outcome.status[programme]
-    when Patient::ConsentOutcome::GIVEN
+    consent_status = patient.consent_status(programme:)
+    if consent_status.given?
       icon_tick "Consent given", "aqua-green"
-    when Patient::ConsentOutcome::REFUSED
+    elsif consent_status.refused?
       icon_cross "Consent refused", "red"
-    when Patient::ConsentOutcome::CONFLICTS
+    elsif consent_status.conflicts?
       icon_cross "Conflicting consent", "dark-orange"
     end
   end

app/components/app_patient_page_component.html.erb

@@ -67,7 +67,7 @@
 
 <% if display_health_questions? %>
   <%= render AppHealthAnswersCardComponent.new(
-        patient.consent_outcome.latest[programme],
+        patient.latest_consents(programme:),
         heading: "All answers to health questions",
       ) %>
 <% end %>

app/components/app_patient_page_component.rb

@@ -24,7 +24,7 @@ def initialize(
   delegate :patient, :session, to: :patient_session
 
   def display_health_questions?
-    patient.consent_outcome.latest[programme].any?(&:response_given?)
+    patient.latest_consents(programme:).any?(&:response_given?)
   end
 
   def display_gillick_assessment_card?

app/components/app_patient_session_search_result_card_component.rb

@@ -87,11 +87,15 @@ def status_tag
       render AppRegisterStatusTagComponent.new(
                patient_session.register_outcome.status
              )
+    elsif context == :consent
+      statuses =
+        patient_session.programmes.index_with do |programme|
+          patient.consent_status(programme:).status
+        end
+      render AppProgrammeStatusTagsComponent.new(statuses, outcome: :consent)
     else
       outcome =
         case context
-        when :consent
-          patient.consent_outcome
         when :triage
           patient.triage_outcome
         when :outcome

app/components/app_programme_session_table_component.rb

@@ -13,30 +13,33 @@ def initialize(sessions, programme:)
   attr_reader :sessions, :programme
 
   def cohort_count(session:)
-    session.patient_sessions.length.to_s
+    format_number(session.patient_sessions.count)
   end
 
   def number_stat(session:)
-    session.patient_sessions.select { yield it }.length.to_s
+    format_number(session.patient_sessions.select { yield it }.length)
   end
 
   def percentage_stat(session:)
-    total_count = session.patient_sessions.length
-    return nil if total_count.zero?
-
-    count = session.patient_sessions.select { yield it }.length
+    format_percentage(
+      session.patient_sessions.select { yield it }.length,
+      session.patient_sessions.count
+    )
+  end
 
-    number_to_percentage(count / total_count.to_f * 100.0, precision: 0)
+  def no_response_scope(session:)
+    session.patient_sessions.has_consent_status(:no_response, programme:)
   end
 
   def no_response_count(session:)
-    number_stat(session:) { it.patient.consent_outcome.no_response?(programme) }
+    format_number(no_response_scope(session:).count)
   end
 
   def no_response_percentage(session:)
-    percentage_stat(session:) do
-      it.patient.consent_outcome.no_response?(programme)
-    end
+    format_percentage(
+      no_response_scope(session:).count,
+      session.patient_sessions.count
+    )
   end
 
   def triage_needed_count(session:)
@@ -50,4 +53,12 @@ def vaccinated_count(session:)
   def vaccinated_percentage(session:)
     percentage_stat(session:) { it.session_outcome.vaccinated?(programme) }
   end
+
+  def format_number(count) = count.to_s
+
+  def format_percentage(count, total_count)
+    return nil if total_count.zero?
+
+    number_to_percentage(count / total_count.to_f * 100.0, precision: 0)
+  end
 end

app/components/app_session_actions_component.rb

@@ -21,6 +21,8 @@ def render?
 
   attr_reader :session, :patient_sessions
 
+  delegate :programmes, to: :session
+
   def rows
     @rows ||= [
       no_consent_response_row,
@@ -32,24 +34,16 @@ def rows
   end
 
   def no_consent_response_row
-    consent_row(
-      text: "No consent response",
-      status: Patient::ConsentOutcome::NO_RESPONSE
-    )
+    consent_row("No consent response", status: "no_response")
   end
 
   def conflicting_consent_row
-    consent_row(
-      text: "Conflicting consent",
-      status: Patient::ConsentOutcome::CONFLICTS
-    )
+    consent_row("Conflicting consent", status: "conflicts")
   end
 
-  def consent_row(text:, status:)
+  def consent_row(text, status:)
     count =
-      patient_sessions.count do
-        it.patient.consent_outcome.status.values_at(*it.programmes).any?(status)
-      end
+      patient_sessions.has_consent_status(status, programme: programmes).count
 
     return nil if count.zero?
 

app/components/app_session_details_summary_component.rb

@@ -16,6 +16,8 @@ def call
 
   attr_reader :session, :patient_sessions
 
+  delegate :programmes, to: :session
+
   def cohort_row
     count = patient_sessions.length
     href = new_draft_class_import_path(session)
@@ -32,11 +34,11 @@ def cohort_row
   end
 
   def consent_refused_row
-    status = Patient::ConsentOutcome::REFUSED
+    status = "refused"
+
     count =
-      patient_sessions.count do
-        it.patient.consent_outcome.status.values_at(*it.programmes).any?(status)
-      end
+      patient_sessions.has_consent_status(status, programme: programmes).count
+
     href =
       session_consent_path(session, search_form: { consent_status: status })
 

app/components/app_simple_status_banner_component.rb

@@ -52,7 +52,7 @@ def description
 
     if patient.triage_outcome.required?(programme)
       reasons = [
-        if patient.triage_outcome.consent_needs_triage?(programme:)
+        if patient.consent_status(programme:).health_answers_require_follow_up?
           I18n.t(
             :consent_needs_triage,
             scope: %i[
@@ -83,10 +83,11 @@ def description
   end
 
   def who_refused
-    patient.consent_outcome.latest[programme]
+    patient
+      .latest_consents(programme:)
       .select(&:response_refused?)
-      .map(&:who_responded)
       .last
+      &.who_responded
   end
 
   def nurse