Add "file" attachment to DataExport model

Migrate previous `DataExport#data` values into `DataExport#file`.

Start populating the CSV content into the `DataExport#file` field via the `DataExporter` class calls.

app/controllers/data_api/tad_data_exports_controller.rb

@@ -100,7 +100,7 @@ def exports
 
     def serve_export(export)
       export.update!(audit_comment: "File downloaded via API using token ID #{@authenticating_token.id}")
-      send_data export.data, filename: export.filename
+      send_data export.file.download, filename: export.filename
     end
 
     def statement_timeout

app/controllers/support_interface/data_exports_controller.rb

@@ -48,7 +48,8 @@ def create
     def download
       data_export = DataExport.find(params[:id])
       data_export.update!(audit_comment: 'File downloaded')
-      send_data data_export.data, filename: data_export.filename, disposition: :attachment
+
+      redirect_to rails_blob_path(data_export.file, disposition: 'attachment')
     end
 
     def data_set_documentation

app/models/data_export.rb

@@ -233,6 +233,9 @@ class DataExport < ApplicationRecord
   }.freeze
 
   belongs_to :initiator, polymorphic: true, optional: true
+
+  has_one_attached :file
+
   audited except: [:data]
 
   def filename

app/services/data_migrations/migrate_data_export_data_to_file.rb

@@ -0,0 +1,12 @@
+module DataMigrations
+  class MigrateDataExportDataToFile
+    TIMESTAMP = 20240528140244
+    MANUAL_RUN = false
+
+    def change
+      DataExport.find_each do |data_export|
+        data_export.file.attach(io: CSV.new(data_export.data).to_io, filename: data_export.filename)
+      end
+    end
+  end
+end

app/workers/data_exporter.rb

@@ -22,9 +22,10 @@ def perform(importer_class, data_export_type, export_options = {})
     Rails.logger.info 'Finished CSV generation'
 
     Rails.logger.info 'Started writing CSV'
+
     data_export.update!(
-      data: csv_data,
-      completed_at: Time.zone.now,
+      file: { io: CSV.new(csv_data).to_io, filename: data_export.filename },
+      completed_at: Time.current,
     )
 
     Rails.logger.info 'Finished writing CSV. Sidekiq done'

lib/tasks/data.rake

@@ -1,5 +1,6 @@
 DATA_MIGRATION_SERVICES = [
   # do not delete or edit this line - services added below by generator
+  'DataMigrations::MigrateDataExportDataToFile',
   'DataMigrations::RemoveCoursesNotOnPublish',
   'DataMigrations::RemoveIncidentEvictionFeatureFlag',
   'DataMigrations::RemoveCourseHasVacanciesFeatureFlag',

spec/services/data_migrations/migrate_data_export_data_to_file_spec.rb

@@ -0,0 +1,16 @@
+require 'rails_helper'
+
+RSpec.describe DataMigrations::MigrateDataExportDataToFile do
+  let(:csv_string) { "email_template,send_count\nsign_in_email,1" }
+
+  it "updates all existing DataExport records 'data' fields and puts them into 'file' attachments" do
+    data_export = create(:data_export, data: csv_string, file: nil)
+
+    described_class.new.change
+
+    data_export.reload
+
+    expect(data_export.file).to be_attached
+    expect(data_export.file.download).to eq(csv_string)
+  end
+end