dry-rb - New gem releases

We’re happy to announce not one, but four big releases today - dry-validation 0.10, dry-types 0.9, dry-logic 0.4 and the new dry-struct gem! These releases are focused on bug fixes, performance improvements, internal refactorings, and new features, too.

There are a couple of breaking changes, please refer to the changelogs for detailed information:

dry-validation 0.10.0 - CHANGELOG
dry-types 0.9.0 - CHANGELOG
dry-struct 0.1.0 - CHANGELOG
dry-logic 0.4.0 - CHANGELOG

dry-validation 0.10

This version ships with an improved support for messages, with errors and hints generated separately, as well as a big performance boost. There are also a couple of new features that you should find useful.

Errors & Hints

The Result#messages interface works the same as before, and in addition to that we have Result#errors and Result#hints. Here’s how you can use them:

UserSchema = Dry::Validation.Form do
  required(:login).filled(size?: 3..64)
  required(:age).filled(:int?, gt?: 18)
end

UserSchema.(login: '', age: 17).errors
# {:login=>["must be filled"], :age=>["must be greater than 18"]}

UserSchema.(login: '', age: 17).hints
# {:login=>["length must be within 3 - 64"], :age=>[]}

Support for “OR” messages

It’s probably safe to say dry-validation is the first validation library in Ruby which supports error messages for “OR” rules. Check it out:

PostSchema = Dry::Validation.Form do
  required(:tags).filled { array? | str? }
end

PostSchema.(tags: 123).errors
# {:tags=>["must be an array or must be a string"]}

Support for custom blocks as predicates

You can now define a rule using a block which is executed in the context of your schema. This is useful for complex rules which need external collaborators provided by the schema. These blocks are treated as high-level rules, which means that they will not be executed if the values they depend on are not valid.

UserSchema = Dry::Validation.Form do
  configure do
    option :ids

    def self.messages
      super.merge(
        en: { errors: { valid_id: 'id is not valid' } }
      )
    end
  end

  required(:id).filled(:int?)

  validate(valid_id: :id) do |id|
    ids.include?(id)
  end
end

schema = UserSchema.with(ids: [1, 2, 3])

schema.(id: 4).errors
# {:valid_id=>["id is not valid"]}

Optional extensions

We’ve added an API for loading optional extensions, and we already have one - support for dry-monads. If you add dry-monads to your Gemfile, you can load the extension and validation results will become compatible with Either monad.

Dry::Validation.load_extensions(:monads)

UserSchema = Dry::Validation.Form do
  required(:login).filled(size?: 3..64)
  required(:age).filled(:int?, gt?: 18)
end

result = UserSchema.(login: '', age: 17).to_either
result.fmap { |data| data[:login] }.or { 'oops' }.value
# "oops"

result = UserSchema.(login: 'jane', age: 19).to_either
result.fmap { |data| data[:login] }.or { 'oops' }.value
# "jane"

This means if you happen to use dry-transaction or dry-matcher you can easily use validation results with them, without the need to wrap results in Left or Right as it happens automatically.

dry-types 0.9 and the new dry-struct gem

We’ve extracted Struct and Value extensions to a separate gem called dry-struct, as these APIs started to grow fast and there was demand for more features. Along with the extraction, new features have been added.

:strict_with_defaults constructor

You can configure structs constructor to be :strict_with_defaults which means any unexpected keys in an attributes hash will cause an exception, and missing values will use defaults, assuming you defined them.

require 'dry-struct'

module Types
  include Dry::Types.module
end

class Post < Dry::Struct
  constructor_type(:strict_with_defaults)

  Status = Types::String
    .enum('draft', 'published', 'deleted')
    .default('draft')

  attribute :title, Types::String
  attribute :body, Types::String
  attribute :status, Status
end

Post.new(title: 'hello', body: 'hello, for real', status: nil)
# #<Post title="hello" body="hello, for real" status="draft">

Post.new(title: 'hello', body: 'hello, for real')
# [Post.new] :status is missing in Hash input (Dry::Struct::Error)

:permissive constructor

Previously :strict constructor, which is the default one, would silently ignore unexpected keys, now it will raise an error. If you want to rely on the original behavior, simply configure constructor type to :permissive:

require 'dry-struct'

module Types
  include Dry::Types.module
end

class Post < Dry::Struct
  constructor_type(:permissive)

  Status = Types::String
    .enum('draft', 'published', 'deleted')
    .default('draft')

  attribute :title, Types::String
  attribute :body, Types::String
  attribute :status, Status
end

Post.new(title: 'hello', body: 'hello, for real', status: published', oops: 'ignored')
# #<Post title="hello" body="hello, for real" status="published">

dry-logic 0.4

Last but not least - the new version of dry-logic is not just few times faster, but also provides a new API for defining and composing Rules. This library is used as the rule engine by dry-validation and dry-types, but you can use it easily standalone too:

age_rule = Dry::Logic.Rule { |v| !v.nil? }.then(
  Dry::Logic.Rule { |v| v.is_a?(Integer) }.and(Dry::Logic.Rule { |v| v > 18 }))

age_rule.(nil).success?
# true
age_rule.(19).success?
# true
age_rule.('19').success?
# false

Thank you <3

Thank you to all contributors who helped finding bugs, testing out new features, providing great feedback and sending pull requests! dry-rb has grown significantly over the last few months and it wouldn’t be possible to achieve that without your help.

Special thanks go to John Backus for the dry-struct extraction with new features and improving dry-types at the same time.