Persist filters, per user, per view, per browser session

User feedback suggested that filters maintain state because they
often filter patients, move away from the page, and then come back
having to apply the same filters again.

This update will ensure each page with filters maintains its own unique
state. This state can only be cleared with the "Clear filters" button on
the form.

Author: jhenderson

app/components/app_search_component.rb

@@ -98,15 +98,15 @@ class AppSearchComponent < ViewComponent::Base
           <% if show_buttons_in_details? %>
             <div class="app-button-group">
               <%= f.govuk_submit "Update results", secondary: true, class: "app-button--small" %>
-              <%= govuk_button_link_to "Clear filters", @url, class: "app-button--small app-button--secondary" %>
+              <%= govuk_button_link_to "Clear filters", clear_filters_path, class: "app-button--small app-button--secondary" %>
             </div>
           <% end %>
         <% end %>
 
         <% unless show_buttons_in_details? %>
           <div class="app-button-group">
             <%= f.govuk_submit "Update results", secondary: true, class: "app-button--small" %>
-            <%= govuk_button_link_to "Clear filters", @url, class: "app-button--small app-button--secondary" %>
+            <%= govuk_button_link_to "Clear filters", clear_filters_path, class: "app-button--small app-button--secondary" %>
           </div>
         <% end %>
       <% end %>
@@ -159,4 +159,8 @@ def show_buttons_in_details?
         triage_statuses.any? || year_groups.any?
     )
   end
+
+  def clear_filters_path
+    "#{@url}?search_form[clear_filters]=true"
+  end
 end

app/controllers/concerns/search_form_concern.rb

@@ -6,7 +6,8 @@ module SearchFormConcern
   def set_search_form
     @form =
       SearchForm.new(
-        params.fetch(:search_form, {}).permit(
+        **params.fetch(:search_form, {}).permit(
+          :clear_filters,
           :consent_status,
           :date_of_birth_day,
           :date_of_birth_month,
@@ -18,7 +19,9 @@ def set_search_form
           :session_status,
           :triage_status,
           year_groups: []
-        )
+        ),
+        session: session,
+        request_path: request.path
       )
   end
 end

app/forms/search_form.rb

@@ -5,6 +5,9 @@ class SearchForm
   include ActiveModel::Attributes
   include ActiveRecord::AttributeAssignment
 
+  SESSION_KEY = "search_filters"
+
+  attribute :clear_filters, :boolean
   attribute :consent_status, :string
   attribute :date_of_birth_day, :integer
   attribute :date_of_birth_month, :integer
@@ -17,6 +20,13 @@ class SearchForm
   attribute :triage_status, :string
   attribute :year_groups, array: true
 
+  attr_accessor :session, :request_path
+
+  def initialize(params = {})
+    super(params)
+    handle_session_filters
+  end
+
   def year_groups=(values)
     super(values&.compact_blank&.map(&:to_i)&.compact || [])
   end
@@ -62,4 +72,54 @@ def apply(scope, programme: nil)
 
     scope.order_by_name
   end
+
+  private
+
+  def handle_session_filters
+    if clear_filters
+      clear_from_session
+    elsif has_filters?
+      store_in_session
+    else
+      load_from_session
+    end
+  end
+
+  def store_in_session
+    return if session.nil?
+
+    if has_filters?
+      session[SESSION_KEY] ||= {}
+      session[SESSION_KEY][path_key] = attributes
+    end
+  end
+
+  def load_from_session
+    return if session.nil? || session[SESSION_KEY].blank?
+
+    stored_filters = session[SESSION_KEY][path_key]
+    return if stored_filters.blank?
+
+    assign_attributes(stored_filters)
+  end
+
+  def clear_from_session
+    return if session.nil? || session[SESSION_KEY].blank?
+
+    session[SESSION_KEY].delete(path_key)
+  end
+
+  def has_filters?
+    # An empty string represents the "Any" option
+    attributes
+      .except(:clear_filters)
+      .values
+      .any? { |value| value.present? || value == "" }
+  end
+
+  def path_key
+    # 8 should be more than enough to avoid collisions
+    # for the number of distinct paths.
+    Digest::MD5.hexdigest(request_path).first(8)
+  end
 end

spec/features/filter_state_persistence_spec.rb

@@ -0,0 +1,97 @@
+# frozen_string_literal: true
+
+describe "Filter state persistence" do
+  scenario "filters maintain state across navigation" do
+    given_i_am_signed_in
+
+    when_i_visit_the_consent_page
+    and_i_apply_consent_filters
+    then_the_consent_filters_are_applied
+
+    when_i_navigate_to_another_page
+    and_i_return_to_the_consent_page
+    then_the_consent_filters_are_still_applied
+
+    when_i_clear_the_consent_filters
+    then_i_should_see_no_applied_filters
+
+    when_i_visit_the_triage_page
+    and_i_apply_triage_filters
+    then_the_triage_filters_are_applied
+
+    when_i_navigate_to_another_page
+    and_i_return_to_the_triage_page
+    then_the_triage_filters_are_still_applied
+
+    when_i_visit_the_consent_page
+    then_i_should_see_no_applied_filters
+  end
+
+  def given_i_am_signed_in
+    @programme = create(:programme, :hpv)
+    @organisation =
+      create(:organisation, :with_one_nurse, programmes: [@programme])
+    @session =
+      create(:session, organisation: @organisation, programmes: [@programme])
+
+    sign_in @organisation.users.first
+  end
+
+  def when_i_visit_the_consent_page
+    visit session_consent_path(@session)
+  end
+
+  def and_i_apply_consent_filters
+    choose "Consent given"
+    click_on "Update results"
+  end
+
+  def then_the_consent_filters_are_applied
+    expect(page).to have_checked_field("Consent given")
+  end
+
+  def then_the_consent_filters_are_still_applied
+    expect(page).to have_checked_field("Consent given")
+  end
+
+  def when_i_clear_the_consent_filters
+    click_on "Clear filters"
+  end
+
+  def when_i_navigate_to_another_page
+    visit root_path
+  end
+
+  def and_i_return_to_the_consent_page
+    visit session_consent_path(@session)
+  end
+
+  def when_i_visit_the_triage_page
+    visit session_triage_path(@session)
+  end
+
+  def and_i_apply_triage_filters
+    choose "Safe to vaccinate"
+    click_on "Update results"
+  end
+
+  def then_the_triage_filters_are_applied
+    expect(page).to have_checked_field("Safe to vaccinate")
+  end
+
+  def and_i_return_to_the_triage_page
+    visit session_triage_path(@session)
+  end
+
+  def then_the_triage_filters_are_still_applied
+    expect(page).to have_checked_field("Safe to vaccinate")
+  end
+
+  def when_i_clear_the_triage_filters
+    click_on "Clear filters"
+  end
+
+  def then_i_should_see_no_applied_filters
+    expect(page).to have_checked_field("Any")
+  end
+end

spec/forms/search_form_spec.rb

@@ -1,22 +1,10 @@
 # frozen_string_literal: true
 
 describe SearchForm do
-  subject(:form) do
-    described_class.new(
-      consent_status:,
-      date_of_birth_day:,
-      date_of_birth_month:,
-      date_of_birth_year:,
-      missing_nhs_number:,
-      programme_status:,
-      q:,
-      register_status:,
-      session_status:,
-      triage_status:,
-      year_groups:
-    )
-  end
+  subject(:form) { described_class.new(**params, session:, request_path:) }
 
+  let(:session) { {} }
+  let(:empty_params) { {} }
   let(:consent_status) { nil }
   let(:date_of_birth_day) { Date.current.day }
   let(:date_of_birth_month) { Date.current.month }
@@ -28,6 +16,23 @@
   let(:session_status) { nil }
   let(:triage_status) { nil }
   let(:year_groups) { %w[8 9 10 11] }
+  let(:request_path) { "/a-path" }
+
+  let(:params) do
+    {
+      consent_status:,
+      date_of_birth_day:,
+      date_of_birth_month:,
+      date_of_birth_year:,
+      missing_nhs_number:,
+      programme_status:,
+      q:,
+      register_status:,
+      session_status:,
+      triage_status:,
+      year_groups:
+    }
+  end
 
   context "for patients" do
     let(:scope) { Patient.all }
@@ -207,4 +212,113 @@
       end
     end
   end
+
+  describe "session filter persistence" do
+    let(:another_path) { "/another-path" }
+
+    context "when clear_filters param is present" do
+      it "only clears filters for the current path" do
+        described_class.new(**{ q: "John" }, session:, request_path:)
+        described_class.new(
+          **{ q: "Jane" },
+          session:,
+          request_path: another_path
+        )
+
+        described_class.new(
+          **{ clear_filters: "true" },
+          session:,
+          request_path:
+        )
+
+        form1 = described_class.new(**empty_params, session:, request_path:)
+        expect(form1.q).to be_nil
+
+        form2 =
+          described_class.new(
+            **empty_params,
+            session:,
+            request_path: another_path
+          )
+        expect(form2.q).to eq("Jane")
+      end
+    end
+
+    context "when filters are present in params" do
+      it "persists filters to be loaded in subsequent requests" do
+        described_class.new(**{ q: "John" }, session:, request_path:)
+
+        form = described_class.new(**empty_params, session:, request_path:)
+        expect(form.q).to eq("John")
+      end
+
+      it "overwrites previously stored filters" do
+        described_class.new(**{ q: "John" }, session:, request_path:)
+
+        form1 = described_class.new(**{ q: "Jane" }, session:, request_path:)
+        expect(form1.q).to eq("Jane")
+
+        form2 = described_class.new(**empty_params, session:, request_path:)
+        expect(form2.q).to eq("Jane")
+      end
+
+      it "overrides session filters when 'Any' option is selected (empty string)" do
+        described_class.new(
+          **{ consent_status: "given" },
+          session:,
+          request_path:
+        )
+
+        form1 = described_class.new(**empty_params, session:, request_path:)
+        expect(form1.consent_status).to eq("given")
+
+        form2 =
+          described_class.new(**{ consent_status: "" }, session:, request_path:)
+        expect(form2.consent_status).to eq("")
+
+        form3 = described_class.new(**empty_params, session:, request_path:)
+        expect(form3.consent_status).to eq("")
+      end
+    end
+
+    context "when no filters are present in params but exist in session" do
+      before do
+        described_class.new(
+          **{ q: "John", year_groups: %w[8 11], consent_status: "given" },
+          session:,
+          request_path:
+        )
+      end
+
+      it "loads filters from the session" do
+        form = described_class.new(**empty_params, session:, request_path:)
+
+        expect(form.q).to eq("John")
+        expect(form.year_groups).to eq([8, 11])
+        expect(form.consent_status).to eq("given")
+      end
+    end
+
+    context "with path-specific filters" do
+      it "maintains separate filters for different paths" do
+        described_class.new(**{ q: "John" }, session:, request_path:)
+        described_class.new(
+          **{ q: "Jane" },
+          session:,
+          request_path: another_path
+        )
+
+        form1 = described_class.new(**empty_params, session:, request_path:)
+        expect(form1.q).to eq("John")
+
+        form2 =
+          described_class.new(
+            **empty_params,
+            session:,
+            request_path: another_path
+          )
+        expect(form2.q).to eq("Jane")
+      end
+    end
+  end
 end