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[![Gem Version](https://badge.fury.io/rb/alba.svg)](https://badge.fury.io/rb/alba)
[![CI](https://github.com/okuramasafumi/alba/actions/workflows/main.yml/badge.svg)](https://github.com/okuramasafumi/alba/actions/workflows/main.yml)
[![codecov](https://codecov.io/gh/okuramasafumi/alba/branch/master/graph/badge.svg?token=3D3HEZ5OXT)](https://codecov.io/gh/okuramasafumi/alba)
[![Maintainability](https://api.codeclimate.com/v1/badges/fdab4cc0de0b9addcfe8/maintainability)](https://codeclimate.com/github/okuramasafumi/alba/maintainability)
[![Inline docs](http://inch-ci.org/github/okuramasafumi/alba.svg?branch=main)](http://inch-ci.org/github/okuramasafumi/alba)
![GitHub code size in bytes](https://img.shields.io/github/languages/code-size/okuramasafumi/alba)
![GitHub](https://img.shields.io/github/license/okuramasafumi/alba)
# Alba
Alba is the fastest JSON serializer for Ruby, JRuby, and TruffleRuby.
## Discussions
Alba uses [GitHub Discussions](https://github.com/okuramasafumi/alba/discussions) to openly discuss the project.
If you've already used Alba, please consider posting your thoughts and feelings on [Feedback](https://github.com/okuramasafumi/alba/discussions/categories/feedback). The fact that you enjoy using Alba gives me energy to keep developing Alba!
If you have feature requests or interesting ideas, join us with [Ideas](https://github.com/okuramasafumi/alba/discussions/categories/ideas). Let's make Alba even better, together!
## Why Alba?
Because it's fast, flexible and well-maintained!
### Fast
Alba is faster than most of the alternatives. We have a [benchmark](https://github.com/okuramasafumi/alba/tree/master/benchmark).
### Flexible
Alba provides a small set of DSL to define your serialization logic. It also provides methods you can override to alter and filter serialized hash so that you have full control over the result.
### Maintained
Alba is well-maintained and adds features quickly. [Coverage Status](https://coveralls.io/github/okuramasafumi/alba?branch=master) and [CodeClimate Maintainability](https://codeclimate.com/github/okuramasafumi/alba/maintainability) show the code base is quite healthy.
## Installation
Add this line to your application's Gemfile:
```ruby
gem 'alba'
```
And then execute:
$ bundle install
Or install it yourself as:
$ gem install alba
## Supported Ruby versions
Alba supports CRuby 2.5 and higher and latest JRuby and TruffleRuby.
## Documentation
You can find the documentation on [RubyDoc](https://rubydoc.info/github/okuramasafumi/alba).
## Features
* Conditional attributes and associations
* Selectable backend
* Key transformation
* Root key inference
* Error handling
* Nil handling
* Resource name inflection based on association name
* Circular associations control
* [Experimental] Types for validation and conversion
* No runtime dependencies
## Anti features
* Sorting keys
* Class level support of parameters
* Supporting all existing JSON encoder/decoder
* Cache
* [JSON:API](https://jsonapi.org) support
* And many others
## Usage
### Configuration
Alba's configuration is fairly simple.
#### Backend configuration
Backend is the actual part serializing an object into JSON. Alba supports these backends.
* Oj, the fastest. Gem installation required.
* active_support, mostly for Rails. Gem installation required.
* default or json, with no external dependencies.
You can set a backend like this:
```ruby
Alba.backend = :oj
```
#### Encoder configuration
You can also set JSON encoder directly with a Proc.
```ruby
Alba.encoder = ->(object) { JSON.generate(object) }
```
You can consider setting a backend with Symbol as a shortcut to set encoder.
#### Inference configuration
You can enable inference feature using `enable_inference!` method.
```ruby
Alba.enable_inference!
```
You must install `ActiveSupport` to enable inference.
#### Error handling configuration
You can configure error handling with `on_error` method.
```ruby
Alba.on_error :ignore
```
For the details, see [Error handling section](#error-handling)
### Simple serialization with root key
```ruby
class User
attr_accessor :id, :name, :email, :created_at, :updated_at
def initialize(id, name, email)
@id = id
@name = name
@email = email
@created_at = Time.now
@updated_at = Time.now
end
end
class UserResource
include Alba::Resource
root_key :user
attributes :id, :name
attribute :name_with_email do |resource|
"#{resource.name}: #{resource.email}"
end
end
user = User.new(1, 'Masafumi OKURA', 'masafumi@example.com')
UserResource.new(user).serialize
# => "{\"id\":1,\"name\":\"Masafumi OKURA\",\"name_with_email\":\"Masafumi OKURA: masafumi@example.com\"}"
```
### Serialization with associations
```ruby
class User
attr_reader :id, :created_at, :updated_at
attr_accessor :articles
def initialize(id)
@id = id
@created_at = Time.now
@updated_at = Time.now
@articles = []
end
end
class Article
attr_accessor :user_id, :title, :body
def initialize(user_id, title, body)
@user_id = user_id
@title = title
@body = body
end
end
class ArticleResource
include Alba::Resource
attributes :title
end
class UserResource
include Alba::Resource
attributes :id
many :articles, resource: ArticleResource
end
user = User.new(1)
article1 = Article.new(1, 'Hello World!', 'Hello World!!!')
user.articles << article1
article2 = Article.new(2, 'Super nice', 'Really nice!')
user.articles << article2
UserResource.new(user).serialize
# => '{"id":1,"articles":[{"title":"Hello World!"},{"title":"Super nice"}]}'
```
You can define associations inline if you don't need a class for association.
```ruby
class ArticleResource
include Alba::Resource
attributes :title
end
class UserResource
include Alba::Resource
attributes :id
many :articles, resource: ArticleResource
end
# This class works the same as `UserResource`
class AnotherUserResource
include Alba::Resource
attributes :id
many :articles do
attributes :title
end
end
```
### Inline definition with `Alba.serialize`
`Alba.serialize` method is a shortcut to define everything inline.
```ruby
Alba.serialize(user, root_key: :foo) do
attributes :id
many :articles do
attributes :title, :body
end
end
# => '{"foo":{"id":1,"articles":[{"title":"Hello World!","body":"Hello World!!!"},{"title":"Super nice","body":"Really nice!"}]}}'
```
`Alba.serialize` can be used when you don't know what kind of object you serialize. For example:
```ruby
Alba.serialize(something)
# => Same as `FooResource.new(something).serialize` when `something` is an instance of `Foo`.
```
Although this might be useful sometimes, it's generally recommended to define a class for Resource.
### Inheritance and Ignorance
You can `exclude` or `ignore` certain attributes using `ignoring`.
```ruby
class Foo
attr_accessor :id, :name, :body
def initialize(id, name, body)
@id = id
@name = name
@body = body
end
end
class GenericFooResource
include Alba::Resource
attributes :id, :name, :body
end
class RestrictedFooResource < GenericFooResource
ignoring :id, :body
end
RestrictedFooResource.new(foo).serialize
# => '{"name":"my foo"}'
```
### Key transformation
If you want to use `transform_keys` DSL and you already have `active_support` installed, key transformation will work out of the box, using `ActiveSupport::Inflector`. If `active_support` is not around, you have 2 possibilities:
* install it
* use a [custom inflector](#custom-inflector)
With `transform_keys` DSL, you can transform attribute keys.
```ruby
class User
attr_reader :id, :first_name, :last_name
def initialize(id, first_name, last_name)
@id = id
@first_name = first_name
@last_name = last_name
end
end
class UserResource
include Alba::Resource
attributes :id, :first_name, :last_name
transform_keys :lower_camel
end
user = User.new(1, 'Masafumi', 'Okura')
UserResourceCamel.new(user).serialize
# => '{"id":1,"firstName":"Masafumi","lastName":"Okura"}'
```
You can also transform root key when:
* `Alba.enable_inference!` is called
* `root_key!` is called in Resource class
* `root` option of `transform_keys` is set to true or `Alba.enable_root_key_transformation!` is called.
```ruby
Alba.enable_inference!
class BankAccount
attr_reader :account_number
def initialize(account_number)
@account_number = account_number
end
end
class BankAccountResource
include Alba::Resource
root_key!
attributes :account_number
transform_keys :dash, root: true
end
bank_account = BankAccount.new(123_456_789)
BankAccountResource.new(bank_account).serialize
# => '{"bank-account":{"account-number":123456789}}'
```
This behavior to transform root key will become default at version 2.
Supported transformation types are :camel, :lower_camel and :dash.
#### Custom inflector
A custom inflector can be plugged in as follows...
```ruby
Alba.inflector = MyCustomInflector
```
...and has to implement following interface (the parameter `key` is of type `String`):
```ruby
module InflectorInterface
def camelize(key)
raise "Not implemented"
end
def camelize_lower(key)
raise "Not implemented"
end
def dasherize(key)
raise "Not implemented"
end
end
```
For example you could use `Dry::Inflector`, which implements exactly the above interface. If you are developing a `Hanami`-Application `Dry::Inflector` is around. In this case the following would be sufficient:
```ruby
Alba.inflector = Dry::Inflector.new
```
### Filtering attributes
You can filter attributes by overriding `Alba::Resource#converter` method, but it's a bit tricky.
```ruby
class User
attr_accessor :id, :name, :email, :created_at, :updated_at
def initialize(id, name, email)
@id = id
@name = name
@email = email
end
end
class UserResource
include Alba::Resource
attributes :id, :name, :email
private
# Here using `Proc#>>` method to compose a proc from `super`
def converter
super >> proc { |hash| hash.compact }
end
end
user = User.new(1, nil, nil)
UserResource.new(user).serialize # => '{"id":1}'
```
The key part is the use of `Proc#>>` since `Alba::Resource#converter` returns a `Proc` which contains the basic logic and it's impossible to change its behavior by just overriding the method.
It's not recommended to swap the whole conversion logic. It's recommended to always call `super` when you override `converter`.
### Conditional attributes
Filtering attributes with overriding `convert` works well for simple cases. However, It's cumbersome when we want to filter various attributes based on different conditions for keys.
In these cases, conditional attributes works well. We can pass `if` option to `attributes`, `attribute`, `one` and `many`. Below is an example for the same effect as [filtering attributes section](#filtering-attributes).
```ruby
class User
attr_accessor :id, :name, :email, :created_at, :updated_at
def initialize(id, name, email)
@id = id
@name = name
@email = email
end
end
class UserResource
include Alba::Resource
attributes :id, :name, :email, if: proc { |user, attribute| !attribute.nil? }
end
user = User.new(1, nil, nil)
UserResource.new(user).serialize # => '{"id":1}'
```
### Default
Alba doesn't support default value for attributes, but it's easy to set a default value.
```ruby
class FooResource
attribute :bar do |foo|
foo.bar || 'default bar'
end
end
```
We believe this is clearer than using some (not implemented yet) DSL such as `default` because there are some conditions where default values should be applied (`nil`, `blank?`, `empty?` etc.)
### Inference
After `Alba.enable_inference!` called, Alba tries to infer root key and association resource name.
```ruby
Alba.enable_inference!
class User
attr_reader :id
attr_accessor :articles
def initialize(id)
@id = id
@articles = []
end
end
class Article
attr_accessor :id, :title
def initialize(id, title)
@id = id
@title = title
end
end
class ArticleResource
include Alba::Resource
attributes :title
end
class UserResource
include Alba::Resource
key!
attributes :id
many :articles
end
user = User.new(1)
user.articles << Article.new(1, 'The title')
UserResource.new(user).serialize # => '{"user":{"id":1,"articles":[{"title":"The title"}]}}'
UserResource.new([user]).serialize # => '{"users":[{"id":1,"articles":[{"title":"The title"}]}]}'
```
This resource automatically sets its root key to either "users" or "user", depending on the given object is collection or not.
Also, you don't have to specify which resource class to use with `many`. Alba infers it from association name.
Note that to enable this feature you must install `ActiveSupport` gem.
### Error handling
You can set error handler globally or per resource using `on_error`.
```ruby
class User
attr_accessor :id, :name
def initialize(id, name, email)
@id = id
@name = name
@email = email
end
def email
raise RuntimeError, 'Error!'
end
end
class UserResource
include Alba::Resource
attributes :id, :name, :email
on_error :ignore
end
user = User.new(1, 'Test', 'email@example.com')
UserResource.new(user).serialize # => '{"id":1,"name":"Test"}'
```
This way you can exclude an entry when fetching an attribute gives an exception.
There are four possible arguments `on_error` method accepts.
* `:raise` re-raises an error. This is the default behavior.
* `:ignore` ignores the entry with the error.
* `:nullify` sets the attribute with the error to `nil`.
* Block gives you more control over what to be returned.
The block receives five arguments, `error`, `object`, `key`, `attribute` and `resource class` and must return a two-element array. Below is an example.
```ruby
# Global error handling
Alba.on_error do |error, object, key, attribute, resource_class|
if resource_class == MyResource
['error_fallback', object.error_fallback]
else
[key, error.message]
end
end
```
### Nil handling
Sometimes we want to convert `nil` to different values such as empty string. Alba provides a flexible way to handle `nil`.
```ruby
class User
attr_reader :id, :name, :age
def initialize(id, name = nil, age = nil)
@id = id
@name = name
@age = age
end
end
class UserResource
include Alba::Resource
on_nil { '' }
root_key :user, :users
attributes :id, :name, :age
end
UserResource.new(User.new(1)).serialize
# => '{"user":{"id":1,"name":"","age":""}}'
```
You can get various information via block parameters.
```ruby
class UserResource
include Alba::Resource
on_nil do |object, key|
if key == age
20
else
"User#{object.id}"
end
end
root_key :user, :users
attributes :id, :name, :age
end
UserResource.new(User.new(1)).serialize
# => '{"user":{"id":1,"name":"User1","age":20}}'
```
You can also set global nil handler.
```ruby
Alba.on_nil { 'default name' }
class Foo
attr_reader :name
def initialize(name)
@name = name
end
end
class FooResource
include Alba::Resource
key :foo
attributes :name
end
FooResource.new(Foo.new).serialize
# => '{"foo":{"name":"default name"}}'
class FooResource2
include Alba::Resource
key :foo
on_nil { '' } # This is applied instead of global handler
attributes :name
end
FooResource2.new(Foo.new).serialize
# => '{"foo":{"name":""}}'
```
### Metadata
You can set a metadata with `meta` DSL or `meta` option.
```ruby
class UserResource
include Alba::Resource
root_key :user, :users
attributes :id, :name
meta do
if object.is_a?(Enumerable)
{size: object.size}
else
{foo: :bar}
end
end
end
user = User.new(1, 'Masafumi OKURA', 'masafumi@example.com')
UserResource.new([user]).serialize
# => '{"users":[{"id":1,"name":"Masafumi OKURA"}],"meta":{"size":1}}'
# You can merge metadata with `meta` option
UserResource.new([user]).serialize(meta: {foo: :bar})
# => '{"users":[{"id":1,"name":"Masafumi OKURA"}],"meta":{"size":1,"foo":"bar"}}'
# You can set metadata with `meta` option alone
class UserResourceWithoutMeta
include Alba::Resource
root_key :user, :users
attributes :id, :name
end
UserResource.new([user]).serialize(meta: {foo: :bar})
# => '{"users":[{"id":1,"name":"Masafumi OKURA"}],"meta":{"foo":"bar"}}'
```
You can use `object` method to access the underlying object and `params` to access the params in `meta` block.
Note that setting root key is required when setting a metadata.
### Circular associations control
**Note that this feature works correctly since version 1.3. In previous versions it doesn't work as expected.**
You can control circular associations with `within` option. `within` option is a nested Hash such as `{book: {authors: books}}`. In this example, Alba serializes a book's authors' books. This means you can reference `BookResource` from `AuthorResource` and vice versa. This is really powerful when you have a complex data structure and serialize certain parts of it.
For more details, please refer to [test code](https://github.com/okuramasafumi/alba/blob/master/test/usecases/circular_association_test.rb)
### Experimental support of types
You can validate and convert input with types.
```ruby
class User
attr_reader :id, :name, :age, :bio, :admin, :created_at
def initialize(id, name, age, bio = '', admin = false) # rubocop:disable Style/OptionalBooleanParameter
@id = id
@name = name
@age = age
@admin = admin
@bio = bio
@created_at = Time.new(2020, 10, 10)
end
end
class UserResource
include Alba::Resource
attributes :name, id: [String, true], age: [Integer, true], bio: String, admin: [:Boolean, true], created_at: [String, ->(object) { object.strftime('%F') }]
end
user = User.new(1, 'Masafumi OKURA', '32', 'Ruby dev')
UserResource.new(user).serialize
# => '{"name":"Masafumi OKURA","id":"1","age":32,"bio":"Ruby dev","admin":false,"created_at":"2020-10-10"}'
```
Notice that `id` and `created_at` are converted to String and `age` is converted to Integer.
If type is not correct and auto conversion is disabled (default), `TypeError` occurs.
```ruby
user = User.new(1, 'Masafumi OKURA', '32', nil) # bio is nil and auto conversion is disabled for bio
UserResource.new(user).serialize
# => TypeError, 'Attribute bio is expected to be String but actually nil.'
```
Note that this feature is experimental and interfaces are subject to change.
### Caching
Currently, Alba doesn't support caching, primarily due to the behavior of `ActiveRecord::Relation`'s cache. See [the issue](https://github.com/rails/rails/issues/41784).
## Rails
When you use Alba in Rails, you can create an initializer file with the line below for compatibility with Rails JSON encoder.
```ruby
Alba.backend = :active_support
# or
Alba.backend = :oj_rails
```
## Why named "Alba"?
The name "Alba" comes from "albatross", a kind of birds. In Japanese, this bird is called "Aho-dori", which means "stupid bird". I find it funny because in fact albatrosses fly really fast. I hope Alba looks stupid but in fact it does its job quick.
## Pioneers
There are great pioneers in Ruby's ecosystem which does basically the same thing as Alba does. To name a few:
* [ActiveModelSerializers](https://github.com/rails-api/active_model_serializers) a.k.a AMS, the most famous implementation of JSON serializer for Ruby
* [Blueprinter](https://github.com/procore/blueprinter) shares some concepts with Alba
## Development
After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake test` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
## Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/okuramasafumi/alba. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [code of conduct](https://github.com/okuramasafumi/alba/blob/master/CODE_OF_CONDUCT.md).
## License
The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).
## Code of Conduct
Everyone interacting in the Alba project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/okuramasafumi/alba/blob/master/CODE_OF_CONDUCT.md).