fix: maintain per_page param in associations

app/controllers/avo/base_controller.rb

@@ -316,14 +316,14 @@ def set_index_params
 
       # Pagination
       @index_params[:page] = params[:page] || page_from_session || 1
-      @index_params[:per_page] = Avo.configuration.per_page
-
-      if cookies[:per_page].present?
-        @index_params[:per_page] = cookies[:per_page]
-      end
+      @index_params[:per_page] = cookies[:per_page] || Avo.configuration.per_page
 
       if @parent_record.present?
-        @index_params[:per_page] = Avo.configuration.via_per_page
+        per_page_key = "#{@record.to_global_id}.has_many.#{@resource.class.to_s.parameterize}.per_page"
+        session[per_page_key] = params[:per_page] || session[per_page_key]
+        per_page_from_session = session[per_page_key]
+
+        @index_params[:per_page] = per_page_from_session || Avo.configuration.via_per_page
       end
 
       if params[:per_page].present?

spec/system/avo/tabs_spec.rb

@@ -200,4 +200,26 @@
     expect(page).to have_css('a.current[role="link"][aria-disabled="true"][aria-current="page"]', text: "2")
     expect(page).to have_text "Displaying items 9-9 of 9 in total"
   end
+
+  it "keeps the per_page on association when back is used" do
+    visit avo.resources_user_path user
+
+    find('a[data-selected="false"][data-tabs-tab-name-param="Projects"]').click
+    within("#has_and_belongs_to_many_field_show_projects") do
+      expect(page).to have_text "Displaying items 1-8 of 9 in total"
+      find("select#per_page.appearance-none").select("24")
+    end
+
+    expect(page).to have_text "Displaying 9 items"
+    expect(find("select#per_page.appearance-none").find("option[selected]").text).to eq("24")
+
+    find_all('a[aria-label="View project"]')[0].click
+    wait_for_loaded
+
+    page.go_back
+    wait_for_loaded
+
+    expect(page).to have_text "Displaying 9 items"
+    expect(find("select#per_page.appearance-none").find("option[selected]").text).to eq("24")
+  end
 end