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https://github.com/alassek/activerecord-pg_enum
Integrate PostgreSQL's enumerated types with the Rails enum feature
https://github.com/alassek/activerecord-pg_enum
enum enumerated-types migrations postgresql ruby-on-rails
Last synced: about 2 months ago
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Integrate PostgreSQL's enumerated types with the Rails enum feature
- Host: GitHub
- URL: https://github.com/alassek/activerecord-pg_enum
- Owner: alassek
- License: mit
- Created: 2018-06-24T00:20:19.000Z (over 6 years ago)
- Default Branch: main
- Last Pushed: 2022-09-19T19:56:58.000Z (about 2 years ago)
- Last Synced: 2024-04-23T17:33:07.806Z (5 months ago)
- Topics: enum, enumerated-types, migrations, postgresql, ruby-on-rails
- Language: Ruby
- Size: 118 KB
- Stars: 167
- Watchers: 3
- Forks: 9
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
# ActiveRecord::PGEnum [](https://app.circleci.com/pipelines/github/alassek/activerecord-pg_enum)
**Note**: This was originally written before Rails added support for native enums. See the comments in [version
support](#version-support).
The `enum` feature in Rails has bad developer ergonomics. It uses integer types at the DB layer, which means trying to understand SQL output is a pain.
Using the easy form of the helper syntax is a minor footgun:
```ruby
enum status: %w[new active archived]
```
It's not obvious that the above code is order-dependent, but if you decide to add a new enum anywhere but the end, you're in trouble.
If you choose the use `varchar` fields instead, now you have to write annoying check constraints and lose the efficient storage.
```ruby
enum status: { new: "new", active: "active", archived: "archived" }
```
Nobody has time to write that nonsense.
## Enumerated Types: The Best of Both Worlds
Did you know you can define your own types in PostgreSQL? You can, and this type system also supports enumeration.
```SQL
CREATE TYPE status_type AS ENUM ('new', 'active', 'archived');
```
Not only does this give you full type safety at the DB layer, the implementation is highly efficient. An enum value only takes up [four bytes](https://www.postgresql.org/docs/11/datatype-enum.html).
The best part is that PostgreSQL supports inserting new values at any point of the list without having to migrate your data.
```SQL
ALTER TYPE status_type ADD VALUE 'pending' BEFORE 'active';
```
## schema.rb Support
The principle motivation of this gem is to seamlessly integrate PG enums into your `schema.rb` file. This means you can use them in your database columns without switching to `structure.sql`.
```ruby
ActiveRecord::Schema.define(version: 2019_06_19_214914) do
# These are extensions that must be enabled in order to support this database
enable_extension "plpgsql"
create_enum "status_type", %w[new pending active archived]
create_table "orders", id: :serial, force: :cascade do |t|
t.enum "status", as: "status_type", default: "new"
end
end
```
## Version support
Every version of Rails with an `enum` macro is supported. This means 4.1 through master. Yes, this was annoying and difficult.
The monkeypatches in this library are extremely narrow and contained; the dirty hacks I had to do to make 4.1 work, for instance, have no impact on 6.0.
Monkeypatching Rails internals is **scary**. So this library has a comprehensive test suite that runs against every known minor version.
Rails 7 added support for native enums, but they have so far neglected to support altering or dropping enums in the API,
so this gem remains to fill in the gaps. I expect to slowly deprecate this over time.
## Installation
Add this line to your application's Gemfile:
```ruby
gem 'activerecord-pg_enum'
```
And then execute:
$ bundle
## Usage
### Migrations
Defining a new ENUM
```ruby
class AddContactMethodType < ActiveRecord::Migration[5.2]
def up
create_enum "contact_method_type", %w[Email Phone]
end
def down
drop_enum "contact_method_type"
end
end
```
Adding a value to an existing ENUM (you must disable the wrapping transaction on PostgreSQL versions older than 12)
```ruby
class AddSMSToContactMethodType < ActiveRecord::Migration[5.2]
disable_ddl_transaction!
def up
add_enum_value "contact_method_type", "SMS", before: "Phone"
end
def down
raise ActiveRecord::IrreversibleMigration
end
end
```
Adding an enum column to a table
```ruby
class AddStatusToOrder < ActiveRecord::Migration[5.2]
def change
change_table :orders do |t|
t.enum :status, as: "status_type", default: "new"
end
end
end
```
Renaming an enum type
```ruby
class RenameStatusType < ActiveRecord::Migration[6.0]
def change
rename_enum "status_type", to: "order_status_type"
end
end
```
```SQL
ALTER TYPE status_type RENAME TO order_status_type;
```
**PostgreSQL 10+ required**:
Changing an enum label
```ruby
class ChangeStatusHoldLabel < ActiveRecord::Migration[6.0]
def change
rename_enum_value "status_type", from: "on hold", to: "OnHold"
end
end
```
```SQL
ALTER TYPE status_type RENAME VALUE 'on hold' TO 'OnHold';
```
### Module Builder
```ruby
class ContactInfo < ActiveRecord::Base
include PGEnum(contact_method: %w[Email SMS Phone])
end
```
The generated module calls the official `enum` method converting array syntax into strings. The above example is equivalent to:
```ruby
class ContactInfo < ActiveRecord::Base
enum contact_method: { Email: "Email", SMS: "SMS", Phone: "Phone" }
end
```
Additionally, `enum` options are fully supported, for example
```ruby
class User < ActiveRecord::Base
include PGEnum(status: %w[active inactive deleted], _prefix: 'user', _suffix: true)
end
```
is equivalent to
```ruby
class User < ActiveRecord::Base
enum status: { active: 'active', inactive: 'inactive', deleted: 'deleted' }, _prefix: 'user', _suffix: true
end
```
There's no technical reason why you couldn't detect enum columns at startup time and automatically do this wireup, but I feel that the benefit of self-documenting outweighs the convenience.
## Development
After checking out the repo, run `bin/setup` to install dependencies. Then, run `appraisal rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
Test a specific version with `appraisal 6.0 rake spec`. This is usually necessary because different versions have different Ruby version support.
To install this gem onto your local machine, run `bundle exec rake install`.
## Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/alassek/activerecord-pg_enum.
## License
The gem is available as open source under the terms of the [MIT License](http://opensource.org/licenses/MIT).