# EnumerateIt

Enumerations for Ruby with some magic powers! 🎩

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**EnumerateIt** helps you to declare and use enumerations in a very simple and
flexible way.

### Why would I want a gem if Rails already has native enumerations support?

Firstly, although **EnumerateIt** works well with **Rails**, it isn't required!
It means you can add it to any **Ruby** project! Secondly, you can
[define your enumerations in classes](https://github.com/lucascaton/enumerate_it#creating-enumerations),
so you can **add behaviour** and also **reuse** them! 😀

---

<!-- Tocer[start]: Auto-generated, don't remove. -->

## Table of Contents

- [EnumerateIt](#enumerateit)
  - [Why would I want a gem if Rails already has native enumerations support?](#why-would-i-want-a-gem-if-rails-already-has-native-enumerations-support)
  - [Table of Contents](#table-of-contents)
  - [Installation](#installation)
  - [Using with Rails](#using-with-rails)
  - [Creating enumerations](#creating-enumerations)
    - [Sorting enumerations](#sorting-enumerations)
  - [Using enumerations](#using-enumerations)
  - [FAQ](#faq)
    - [Why define enumerations outside the class that uses them?](#why-define-enumerations-outside-the-class-that-uses-them)
    - [Can I use `enumerate_it` gem without Rails?](#can-i-use-enumerate_it-gem-without-rails)
    - [What versions of Ruby and Rails are supported?](#what-versions-of-ruby-and-rails-are-supported)
    - [Can I set a value to always be at the end of a sorted list?](#can-i-set-a-value-to-always-be-at-the-end-of-a-sorted-list)
  - [I18n](#i18n)
    - [Translate a name-spaced enumeration](#translate-a-name-spaced-enumeration)
  - [Handling a legacy database](#handling-a-legacy-database)
  - [Changelog](#changelog)
  - [Note on Patches/Pull Requests](#note-on-patchespull-requests)
  - [Copyright](#copyright)

<!-- Tocer[finish]: Auto-generated, don't remove. -->

## Installation

```bash
gem install enumerate_it
```

## Using with Rails

Add the gem to your `Gemfile`:

```ruby
gem 'enumerate_it'
```

You can use a Rails generator to create both an enumeration and its locale file:

```bash
rails generate enumerate_it:enum --help
```

## Creating enumerations

Enumerations are created as classes and you should put them inside
`app/enumerations` folder.

You can pass an array of symbols, so that the respective value for each symbol
will be the stringified version of the symbol itself:

```ruby
class RelationshipStatus < EnumerateIt::Base
  associate_values(
    :single,
    :married,
    :divorced
  )
end
```

This will create some nice stuff:

- Each enumeration's value will turn into a constant:

  ```ruby
  RelationshipStatus::SINGLE
  #=> 'single'

  RelationshipStatus::MARRIED
  #=> 'married'
  ```

- You can retrieve a list with all the enumeration codes:

  ```ruby
  RelationshipStatus.list
  #=> ['divorced', 'married', 'single']
  ```

- You can retrieve a JSON with all the enumeration codes:

  ```ruby
  RelationshipStatus.to_json
  #=> "[{\"value\":\"divorced\",\"label\":\"Divorced\"},{\"value\":\"married\", ...
  ```

- You can get an array of options, ready to use with the `select`, `select_tag`,
  etc. family of Rails helpers.

  ```ruby
  RelationshipStatus.to_a
  #=> [['Divorced', 'divorced'], ['Married', 'married'], ['Single', 'single']]
  ```

- You can retrieve a list with values for a group of enumeration constants.

  ```ruby
  RelationshipStatus.values_for %w(MARRIED SINGLE)
  #=> ['married', 'single']
  ```

- You can retrieve the value for a specific enumeration constant:

  ```ruby
  RelationshipStatus.value_for('MARRIED')
  #=> 'married'
  ```

- You can retrieve the symbol used to declare a specific enumeration value:

  ```ruby
  RelationshipStatus.key_for(RelationshipStatus::MARRIED)
  #=> :married
  ```

- You can iterate over the list of the enumeration's values:

  ```ruby
  RelationshipStatus.each_value { |value| ... }
  ```

- You can iterate over the list of the enumeration's translations:

  ```ruby
  RelationshipStatus.each_translation { |translation| ... }
  ```

- You can also retrieve all the translations of the enumeration:

  ```ruby
  RelationshipStatus.translations
  ```

- You can ask for the enumeration's length:

  ```ruby
  RelationshipStatus.length
  #=> 3
  ```

### Sorting enumerations

When calling methods like `to_a`, `to_json` and `list`, the returned values will
be sorted by default in the same order passed to `associate_values` call.

However, if you want to overwrite the default sort mode, you can use the
`sort_by` class method:

```ruby
class RelationshipStatus < EnumerateIt::Base
  associate_values :single, :married

  sort_by :translation
end
```

The `sort_by` method accepts one of the following values:

| Value          | Behavior                                                                                     |
| :------------- | :------------------------------------------------------------------------------------------- |
| `:none`        | The default behavior, will return values in order that was passed to `associate_values` call |
| `:name`        | Will sort the returned values based on the name of each enumeration option                   |
| `:translation` | will sort the returned values based on their translations                                    |
| `:value`       | See [Handling a legacy database](#handling-a-legacy-database) section for more details       |

## Using enumerations

The cool part is that you can use these enumerations with any class:

```ruby
# ActiveRecord instance
class Person < ApplicationRecord
  has_enumeration_for :relationship_status
end
```

```ruby
# Non-ActiveRecord instance
class Person
  extend EnumerateIt
  attr_accessor :relationship_status

  has_enumeration_for :relationship_status
end
```

> **Note:** **EnumerateIt** will try to load an enumeration class based on the
> camelized attribute name. If you have a different name, you can specify it by
> using the `with` option:
>
> `has_enumeration_for :relationship_status, with: RelationshipStatus`

This will create:

- A "humanized" version of the hash's key to humanize the attribute's value:

  ```ruby
  p = Person.new
  p.relationship_status = RelationshipStatus::DIVORCED
  p.relationship_status_humanize
  #=> 'Divorced'
  ```

- A translation for your options, if you include a locale to represent it (see
  more in the [I18n section](#i18n)).

  ```ruby
  p = Person.new
  p.relationship_status = RelationshipStatus::DIVORCED
  p.relationship_status_humanize
  #=> 'Divorciado'
  ```

- The associated enumerations, which can be retrieved with the `enumerations`
  class method:

  ```ruby
  Person.enumerations
  #=> { relationship_status: RelationshipStatus }
  ```

- A helper method for each enumeration option, if you pass the `create_helpers`
  option as `true`:

  ```ruby
  class Person < ApplicationRecord
    has_enumeration_for :relationship_status, with: RelationshipStatus, create_helpers: true
  end

  p = Person.new
  p.relationship_status = RelationshipStatus::MARRIED

  p.married?
  #=> true

  p.divorced?
  #=> false
  ```

  It's also possible to "namespace" the created helper methods, passing a hash
  to the `create_helpers` option. This can be useful when two or more of the
  enumerations used share the same constants:

  ```ruby
  class Person < ApplicationRecord
    has_enumeration_for :relationship_status,
      with: RelationshipStatus, create_helpers: { prefix: true }
  end

  p = Person.new
  p.relationship_status = RelationshipStatus::MARRIED

  p.relationship_status_married?
  #=> true

  p.relationship_status_divorced?
  #=> false
  ```

  You can define polymorphic behavior for the enumeration values, so you can
  define a class for each of them:

  ```ruby
  class RelationshipStatus < EnumerateIt::Base
    associate_values :married, :single

    class Married
      def saturday_night
        'At home with the kids'
      end
    end

    class Single
      def saturday_night
        'Party hard!'
      end
    end
  end

  class Person < ApplicationRecord
    has_enumeration_for :relationship_status,
      with: RelationshipStatus, create_helpers: { polymorphic: true }
  end

  p = Person.new
  p.relationship_status = RelationshipStatus::MARRIED
  p.relationship_status_object.saturday_night
  #=> 'At home with the kids'

  p.relationship_status = RelationshipStatus::SINGLE
  p.relationship_status_object.saturday_night
  #=> 'Party hard!'
  ```

  You can also change the suffix `_object`, using the `suffix` option:

  ```ruby
  class Person < ApplicationRecord
    has_enumeration_for :relationship_status,
      with: RelationshipStatus, create_helpers: { polymorphic: { suffix: '_mode' } }
  end

  p.relationship_status_mode.saturday_night
  ```

  The `create_helpers` also creates some mutator helper methods, that can be
  used to change the attribute's value.

  ```ruby
  p = Person.new
  p.married!

  p.married?
  #=> true
  ```

- A scope method for each enumeration option if you pass the `create_scopes`
  option as `true`:

  ```ruby
  class Person < ApplicationRecord
    has_enumeration_for :relationship_status, with: RelationshipStatus, create_scopes: true
  end

  Person.married.to_sql
  #=> SELECT "users".* FROM "users" WHERE "users"."relationship_status" = "married"
  ```

  The `:create_scopes` also accepts `prefix` option.

  ```ruby
  class Person < ApplicationRecord
    has_enumeration_for :relationship_status,
      with: RelationshipStatus, create_scopes: { prefix: true }
  end

  Person.relationship_status_married.to_sql
  ```

- An inclusion validation (if your class can manage validations and responds to
  `validates_inclusion_of`):

  ```ruby
  class Person < ApplicationRecord
    has_enumeration_for :relationship_status, with: RelationshipStatus
  end

  p = Person.new(relationship_status: 'invalid')
  p.valid?
  #=> false
  p.errors[:relationship_status]
  #=> 'is not included in the list'
  ```

- A presence validation (if your class can manage validations and responds to
  `validates_presence_of` and you pass the `required` options as `true`):

  ```ruby
  class Person < ApplicationRecord
    has_enumeration_for :relationship_status, required: true
  end

  p = Person.new relationship_status: nil
  p.valid?
  #=> false
  p.errors[:relationship_status]
  #=> "can't be blank"
  ```

  If you pass the `skip_validation` option as `true`, it will not create any
  validations:

  ```ruby
  class Person < ApplicationRecord
    has_enumeration_for :relationship_status, with: RelationshipStatus, skip_validation: true
  end

  p = Person.new(relationship_status: 'invalid')
  p.valid?
  #=> true
  ```

Remember that you can add validations to any kind of class and not only
`ActiveRecord` ones.

## FAQ

#### Why define enumerations outside the class that uses them?

- It's clearer.
- You can add behaviour to the enumeration class.
- You can reuse the enumeration inside other classes.

#### Can I use `enumerate_it` gem without Rails?

You sure can! 😄

#### What versions of Ruby and Rails are supported?

- **Ruby**: `3.0+`
- **Rails** `6.0+`

All versions are tested via
[GitHub Actions](https://github.com/lucascaton/enumerate_it/blob/HEAD/.github/workflows/ci.yml).

#### Can I set a value to always be at the end of a sorted list?

Yes,
[see more details here](https://github.com/lucascaton/enumerate_it/issues/60).

## I18n

I18n lookup is provided on both `_humanized` and `Enumeration#to_a` methods,
given the hash key is a Symbol. The I18n strings are located on
`enumerations.<enumeration_name>.<key>`:

```yaml
# Your locale file
pt-BR:
  enumerations:
    relationship_status:
      married: Casado
```

```ruby
class RelationshipStatus < EnumerateIt::Base
  associate_values(
    :married,
    :single
  )
end

p = Person.new
p.relationship_status = RelationshipStatus::MARRIED
p.relationship_status_humanize # Existent key
#=> 'Casado'

p.relationship_status = RelationshipStatus::SINGLE
p.relationship_status_humanize # Non-existent key
#=> 'Single'
```

You can also translate specific values:

```ruby
status = RelationshipStatus::MARRIED
RelationshipStatus.t(status)
#=> 'Casado'
```

### Translate a name-spaced enumeration

In order to translate an enumeration in a specific namespace (say
`Design::Color`), you can add the following:

```yaml
pt-BR:
  enumerations:
    "design/color":
      blue: Azul
      red: Vermelho
```

## Handling a legacy database

**EnumerateIt** can help you build a Rails application around a legacy database
which was filled with those small and unchangeable tables used to create foreign
key constraints everywhere, like the following example:

```sql
Table "public.relationship_status"

  Column     |     Type      | Modifiers
-------------+---------------+-----------
 code        | character(1)  | not null
 description | character(11) |

Indexes:
  "relationship_status_pkey" PRIMARY KEY, btree (code)

SELECT * FROM relationship_status;

code |  description
---- +--------------
1    | Single
2    | Married
3    | Divorced
```

You might also have something like a `users` table with a `relationship_status`
column and a foreign key pointing to the `relationship_status` table.

While this is a good thing from the database normalization perspective, managing
these values in tests is very hard. Doing database joins just to get the
description of some value is absurd. And, more than this, referencing them in
the code using
[magic numbers](<https://en.wikipedia.org/wiki/Magic_number_(programming)>) was
terrible and meaningless: what does it mean when we say that someone or
something is `2`?

To solve this, you can pass a **hash** to your enumeration values:

```ruby
class RelationshipStatus < EnumerateIt::Base
  associate_values(
    single:   1,
    married:  2,
    divorced: 3
  )
end
```

```ruby
RelationshipStatus::MARRIED
#=> 2
```

You can also sort it by its **value** using `sort_by :value`.

## Changelog

Changes follows the [Semantic Versioning](https://semver.org/) specification and
you can see them on the [releases page](../../releases).

## Note on Patches/Pull Requests

- Fork the project.
- Make your feature addition or bug fix.
- Add tests for it. This is important so we don't break it in a future version
  unintentionally.
- [Optional] Run the tests against a specific Gemfile:
  `$ bundle exec appraisal rails_7.0 rake spec`.
- Run the tests against all supported versions: `$ bundle exec rake` (or
  `$ bundle exec wwtd`)
- Commit, but please do not mess with `Rakefile`, version, or history.
- Send a Pull Request. Bonus points for topic branches.

## Copyright

Copyright (c) 2010-2024 Cássio Marques and Lucas Caton. See `LICENSE` file for
details.