calculate duration for existing work packages

db/migrate/20220525154549_add_duration_to_work_packages.rb

@@ -3,5 +3,28 @@ class AddDurationToWorkPackages < ActiveRecord::Migration[6.1]
     add_column :work_packages, :duration, :integer
 
     add_column :work_package_journals, :duration, :integer
+
+    reversible do |dir|
+      dir.up do
+        set_duration(:work_packages)
+        set_duration(:work_package_journals)
+      end
+    end
+  end
+
+  private
+
+  def set_duration(table)
+    execute <<~SQL.squish
+      UPDATE
+        #{table}
+      SET
+        duration = CASE
+                   WHEN start_date IS NULL OR due_date IS NULL
+                   THEN 1
+                   ELSE
+                     due_date - start_date + 1
+                   END
+    SQL
   end
 end