Automatically expand encrypted arguments to support querying both encrypted and unencrypted data

Active Record Encryption supports querying the db using deterministic attributes. For example:

Contact.find_by(email_address: "")

The value “” will get encrypted automatically to perform the query. But there is a problem while the data is being encrypted. This won't work. During that time, you need these queries to be:

Contact.find_by(email_address: [ "", "<encrypted>" ])

This patches ActiveRecord to support this automatically. It addresses both:

  • ActiveRecord::Base: Used in +Contact.find_by_email_address(…)+

  • ActiveRecord::Relation: Used in +Contact.internal.find_by_email_address(…)+

ActiveRecord::Base relies on ActiveRecord::Relation (ActiveRecord::QueryMethods) but it does some prepared statements caching. That's why we need to intercept ActiveRecord::Base as soon as it's invoked (so that the proper prepared statement is cached).

When modifying this file run performance tests in test/performance/extended_deterministic_queries_performance_test.rb to

make sure performance overhead is acceptable.

We will extend this to support previous “encryption context” versions in future iterations

@TODO Experimental. Support for every kind of query is pending @TODO It should not patch anything if not needed (no previous schemes or no support for previous encryption schemes)