Merge pull request #12592 from mkllnk/report-rendering

Load large on-screen reports on demand

app/jobs/report_job.rb

@@ -53,7 +53,14 @@ class ReportJob < ApplicationJob
   end
 
   def actioncable_content(format, blob)
-    return blob.result if format.to_sym == :html
+    if format.to_sym == :html
+      return blob.result if blob.byte_size < 10**6 # 1 MB
+
+      return render(
+        partial: "admin/reports/display",
+        locals: { file_url: blob.expiring_service_url }
+      )
+    end
 
     render(partial: "admin/reports/download", locals: { file_url: blob.expiring_service_url })
   end

app/views/admin/reports/_display.html.haml

@@ -0,0 +1,5 @@
+.download
+  %p.notice= t ".report_is_big"
+  %p= link_to t(".display_anyway"), file_url, target: "_blank",
+    class: "button icon icon-file",
+    onclick: "(async function (element) { element.outerHTML = await (await fetch(element.href)).text() })(this); return false;"

config/locales/en.yml

@@ -1670,6 +1670,9 @@ en:
       pack_by_customer: Pack By Customer
       pack_by_supplier: Pack By Supplier
       pack_by_product: Pack By Product
+      display:
+        report_is_big: "This report is big and may slow down your device."
+        display_anyway: "Display anyway"
       download:
         button: "Download Report"
       show:

spec/system/admin/reports_spec.rb

@@ -55,6 +55,30 @@ RSpec.describe '
       expect(page).to have_content "Müller"
     end
 
+    it "requires confirmation to display big reports" do
+      # Mock data is much faster and accurate than creating many orders:
+      allow_any_instance_of(Reporting::Reports::Customers::Base)
+        .to receive(:columns).and_return(
+          {
+            first_name: proc { |_| "Little Bobby Tables " * (10**5) }, # 2 MB
+          }
+        )
+
+      # We still need an order for the report to render a row:
+      create(:completed_order_with_totals)
+
+      login_as_admin
+      visit admin_report_path(report_type: :customers)
+      run_report
+
+      expect(page).to have_content "This report is big"
+      expect(page).not_to have_content "Little Bobby Tables"
+
+      click_on "Display anyway"
+      expect(page).to have_content "FIRST NAME"
+      expect(page).to have_content "Little Bobby Tables"
+    end
+
     it "displays a friendly timeout message and offers download" do
       login_as_admin
       visit admin_report_path(report_type: :customers)