Persist Invalid Records with ActiveRecord
tl;dr We can override ActiveRecord#save to keep invalid records in the database along with their validation errors.
Some time ago, I had an unusual design brief for a Rails app:
Even if a user submits an invalid record, we need to (a) save a copy to the database, along with the validation errors, and (b) re-render the form with the error messages as per the default Rails behavior.
The idea behind this design was that administrators could see the unsuccessful submissions and intervene to assist the users if necessary.
If anyone ever finds themselves in a similar situation, here’s what I ended up doing:
I’m going to use a model called Subscription by way of example. This same pattern will work on any ActiveRecord model.
Add a new text column
We’ll serialize the validation errors and store them in a field called record_errors.
# /db/migrations/20130524012635_add_record_errors_to_subscriptions.rb
class AddRecordErrorsToSubscriptions < ActiveRecord::Migration
def change
add_column :subscriptions, :record_errors, :text
end
end
Add an ActiveRecord extension to handle persistence
This module will catch validation failures and persist the record anyway. It’s completely independent of the domain/business logic of the application so I like to store it in /lib. This is the main logic for achieving our required behaviour.
# /lib/save_with_errors.rb
require 'active_record'
require 'active_support'
module SaveWithErrors
def save_with_errors!(*args)
save_without_errors! *args
rescue ActiveRecord::RecordInvalid
save_anyway
raise # this re-raises the exception we just rescued
end
def save_with_errors(*args)
save_without_errors *args or save_anyway
end
def self.included(receiver)
receiver.serialize :record_errors, Hash
receiver.alias_method_chain :save, :errors
receiver.alias_method_chain :save!, :errors
end
private
def save_anyway
dup.tap { |s| s.record_errors = errors.messages }.save(validate: false)
false
end
end
Include our ActiveRecord extension on our model
All we need to do is include the SaveWithErrors module into our ActiveRecord model. We should also require ‘save_with_errors’ in config/application.rb.
# /app/models/subscription.rb
require 'save_with_errors'
class Subscription < ActiveRecord::Base
include SaveWithErrors
attr_accessible :email, :name, :token
validate :valid_token
private
def valid_token
# something meaningful
errors.add :token, 'is invalid' unless token == '12345'
end
end
The Result
Loading development environment (Rails 3.2.13)
> Subscription.create! name: 'My Name', email: 'test@example.com'
SQL (3.6ms) INSERT INTO "subscriptions" ("created_at", "email", "name", "record_errors", "token", "updated_at") VALUES (?, ?, ?, ?, ?, ?) [["created_at", Fri, 24 May 2013 01:55:07 UTC +00:00], ["email", "test@example.com"], ["name", "My Name"], ["record_errors", "--- !omap\n- :token:\n - is invalid\n"], ["token", nil], ["updated_at", Fri, 24 May 2013 01:55:07 UTC +00:00]]
ActiveRecord::RecordInvalid: Validation failed: Token is invalid
[... backtrace ...]
Notice that a record has been inserted, but the exception that we’d expect from create! has still been raised. We can verify this by inspecting the last Subscription record:
> y Subscription.last
Subscription Load (0.3ms) SELECT "subscriptions".* FROM "subscriptions" ORDER BY "subscriptions"."id" DESC LIMIT 1
--- !ruby/object:Subscription
attributes:
id: 19
name: My Name
email: test@example.com
token:
created_at: 2013-05-24 01:55:07.747035000 Z
updated_at: 2013-05-24 01:55:07.747035000 Z
record_errors: !omap
- :token:
- is invalid
Exactly what we want!