Fix for nil user.language_id Bug

db/migrate/20241212180047_set_language_id_not_null_on_users.rb

@@ -0,0 +1,29 @@
+class SetLanguageIdNotNullOnUsers < ActiveRecord::Migration[6.1]
+
+  def up
+    # Ensure default language exists before applying the changes
+    default_language_id = handle_default_language_id
+    # Disallow null values for user.language_id
+    # Also, set all currently null user.language_id values to the app's default language_id
+    change_column_null :users, :language_id, false, default_language_id
+  end
+
+  def down
+    # Allow null values for user.language_id
+    change_column_null :users, :language_id, true
+  end
+
+  private
+
+    # Return Language.default.id or raise an exception if not found, causing the migration to fail
+    def handle_default_language_id
+      default_language = Language.default
+
+      if default_language.nil?
+        Rails.logger.error 'Error: Language.default not found. Please ensure the default language is set.'
+        message = 'Migration aborted: No database changes were performed due to missing Language.default.'
+        raise StandardError, message
+      end
+      default_language.id
+    end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2024_08_20_190548) do
+ActiveRecord::Schema.define(version: 2024_12_12_180047) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -819,7 +819,7 @@
     t.string "api_token"
     t.integer "invited_by_id"
     t.string "invited_by_type"
-    t.integer "language_id"
+    t.integer "language_id", null: false
     t.string "recovery_email"
     t.boolean "active", default: true
     t.integer "department_id"

lib/tasks/update_nil_user_language_ids_from_orgs.rake

@@ -0,0 +1,93 @@
+# frozen_string_literal: true
+
+namespace :data_migration do
+  desc 'Updates nil `user.language_id` values using `user.org.language_id`'
+  task update_nil_user_language_ids_from_orgs: :environment do
+    users_to_be_updated = query_nil_language_users_for_update
+    # Exit rake task if users_to_be_updated is empty
+    ensure_update_needed(users_to_be_updated)
+    # user_ids will be used to later output the updated results
+    user_ids = users_to_be_updated.pluck(:id)
+    # Perform the update
+    update_users(users_to_be_updated)
+    # Output a breakdown of the updated results
+    output_update_results(user_ids)
+    # Output if any users still have nil language_id after update
+    output_remaining_nil_language_users
+    puts 'Rake task completed.'
+  end
+
+  private
+
+  # Queries users that will be updated within this rake task
+  # The following nil_language users WILL NOT be updated within this rake task:
+  # - users where `user.org == nil` or `user.org.language_id == nil`
+  # (However, no such users should exist)
+  def query_nil_language_users_for_update
+    query_nil_language_users.joins(:org)
+                            .where.not(orgs: { language_id: nil })
+  end
+
+  def query_nil_language_users
+    User.where(language_id: nil)
+  end
+
+  # Exits rake task if there is no update to perform
+  # Otherwise, outputs number of users to be updated
+  def ensure_update_needed(users_to_be_updated)
+    if users_to_be_updated.empty?
+      print_and_warn('No users to be updated. Exiting rake task.')
+      exit(0)
+    else
+      puts "Found #{users_to_be_updated.count} users to update."
+    end
+  end
+
+  # Performs a single bulk update on users_to_be_updated
+  def update_users(users_to_be_updated)
+    puts 'Proceeding to use `user.org.language_id` to update each nil `user.language_id`'
+    puts '------------------------------------------------------------------------'
+
+    # Subquery for update_all() action
+    # Fetches `user.org.language_id` for all users in `users_to_be_updated`
+    subquery = Org.where('orgs.id = users.org_id').select(:language_id).limit(1)
+
+    # Batch update `users_to_be_updated` with `user.org.language_id` values from subquery
+    users_to_be_updated.update_all("language_id = (#{subquery.to_sql})")
+
+    puts 'Update complete.'
+  end
+
+  # Outputs a breakdown of the updated language_id counts
+  def output_update_results(user_ids)
+    language_id_counts = User.where(id: user_ids)
+                             .group(:language_id)
+                             .count
+
+    puts 'Summary of language_id counts for updated users:'
+
+    language_id_counts.each do |language_id, count|
+      puts "language_id: #{language_id}, count: #{count}"
+    end
+
+    puts "Total count: #{language_id_counts.values.sum}"
+  end
+
+  def output_remaining_nil_language_users
+    # Query remaining users with nil language_id
+    # Now we are using query_nil_language_users (not query_nil_language_users_for_update)
+    remaining_users = query_nil_language_users
+    if remaining_users.exists?
+      # NOTE: Any remaining nil language_id users will be addressed in the SetLanguageIdNotNullOnUsers migration
+      print_and_warn("#{remaining_users.count} users still have a nil language_id.")
+    else
+      puts 'Successfully updated language_id for all users (i.e. All users now have a non-nil language_id value).'
+    end
+  end
+
+  # Message is printed to console and logs a warning
+  def print_and_warn(message)
+    puts message
+    Rails.logger.warn(message)
+  end
+end