Use rake task

lib/tasks/what_happens_next_markdown.rake

@@ -0,0 +1,59 @@
+class TextHelpers
+  include ActionView::Helpers::TextHelper
+end
+
+namespace :what_happens_next_markdown do
+  desc "Populate what_happens_next_markdown field"
+  task populate: :environment do
+    Form.find_each do |form|
+      formatted_html = TextHelpers.new.simple_format(
+        form.what_happens_next_text,
+        {},
+        sanitize: true,
+        sanitize_options: {
+          tags: %w[a ol ul li p],
+          attributes: %w[href class rel target title],
+        },
+      )
+      markdown = ReverseMarkdown.convert(formatted_html).strip
+      form.what_happens_next_markdown = form.what_happens_next_text.blank? ? "" : markdown
+
+      form.made_live_forms.each do |made_live_form|
+        form_blob = JSON.parse(made_live_form.json_form_blob, symbolize_names: true)
+
+        formatted_html = TextHelpers.new.simple_format(
+          form_blob[:what_happens_next_text],
+          {},
+          sanitize: true,
+          sanitize_options: {
+            tags: %w[a ol ul li p],
+            attributes: %w[href class rel target title],
+          },
+        )
+        markdown = ReverseMarkdown.convert(formatted_html).strip
+        form_blob[:what_happens_next_markdown] = form_blob[:what_happens_next_text].blank? ? "" : markdown
+
+        made_live_form.update!(json_form_blob: form_blob.to_json)
+      end
+
+      form.save!
+    end
+  end
+
+  desc "Depopulate what_happens_next_markdown field"
+  task depopulate: :environment do
+    Form.find_each do |form|
+      form.what_happens_next_markdown = nil
+
+      form.made_live_forms.each do |made_live_form|
+        form_blob = JSON.parse(made_live_form.json_form_blob, symbolize_names: true)
+
+        form_blob[:what_happens_next_markdown] = nil
+
+        made_live_form.update!(json_form_blob: form_blob.to_json)
+      end
+
+      form.save!
+    end
+  end
+end

spec/lib/tasks/what_happens_next_markdown_spec.rb

@@ -0,0 +1,46 @@
+require "rails_helper"
+require "rake"
+
+RSpec.describe "what_happens_next_markdown.rake" do
+  describe "what_happens_next_markdown:populate", type: :task do
+    before do
+      Rake.application.rake_require "tasks/what_happens_next_markdown"
+      Rake::Task.define_task(:environment)
+    end
+
+    it "populates the what_happens_next_markdown field on the form and the live form JSON" do
+      form = create(:form, what_happens_next_text: "You will get a response soon.\n\nIn the meantime:<ul><li>A list item</li></ul>", what_happens_next_markdown: nil)
+      made_live_form = create(:made_live_form, form:)
+
+      Rake::Task["what_happens_next_markdown:populate"].invoke
+
+      form.reload
+      made_live_form.reload
+
+      made_live_form_blob = JSON.parse(made_live_form.json_form_blob, symbolize_names: true)
+      expect(form.what_happens_next_markdown).to eq "You will get a response soon.\n\nIn the meantime:\n\n- A list item"
+      expect(made_live_form_blob[:what_happens_next_markdown]).to eq "You will get a response soon.\n\nIn the meantime:\n\n- A list item"
+    end
+  end
+
+  describe "what_happens_next_markdown:depopulate", type: :task do
+    before do
+      Rake.application.rake_require "tasks/what_happens_next_markdown"
+      Rake::Task.define_task(:environment)
+    end
+
+    it "removes the what_happens_next_markdown content from the form and the live form JSON" do
+      form = create(:form, what_happens_next_text: "You will get a response soon.\n\nIn the meantime:<ul><li>A list item</li></ul>", what_happens_next_markdown: "You will get a response soon.\n\nIn the meantime:\n\n- A list item")
+      made_live_form = create(:made_live_form, form:)
+
+      Rake::Task["what_happens_next_markdown:depopulate"].invoke
+
+      form.reload
+      made_live_form.reload
+
+      made_live_form_blob = JSON.parse(made_live_form.json_form_blob, symbolize_names: true)
+      expect(form.what_happens_next_markdown).to eq nil
+      expect(made_live_form_blob[:what_happens_next_markdown]).to eq nil
+    end
+  end
+end