RethinkDB ORM for Crystal Lang

Extending ActiveModel for attribute definitions, callbacks and validations

• RethinkDB ORM for Crystal Lang
  • Callbacks
  • Associations
    • belongs_to
    • has_many
    • has_one
    • Dependency
  • Indexes
  • Changefeeds
  • Validations
    • ensure_unique
  • Timestamps

Configuration

# Below is the list of settings exposed by RethinkORM and their defaults
RethinkORM::Settings.configure do |settings|
  settings.host = ENV["RETHINKDB_HOST"]? || "localhost"
  settings.port = (ENV["RETHINKDB_PORT"]? || 28015).to_i
  settings.db = ENV["RETHINKDB_DB"]? || ENV["RETHINKDB_DATABASE"]? || "test"
  settings.user = ENV["RETHINKDB_USER"]? || "admin"
  settings.password = ENV["RETHINKDB_PASSWORD"]? || ""
  settings.lock_expire = (ENV["RETHINKDB_LOCK_EXPIRE"]? || 30).to_i.seconds
  settings.lock_timeout = (ENV["RETHINKDB_LOCK_TIMEOUT"]? || 5).to_i.seconds
  settings.retry_interval = (ENV["RETHINKDB_TIMEOUT"]? || 2).to_i.seconds

  # Driver level reconnection attempts
  settings.retry_attempts = ENV["RETHINKDB_RETRIES"]?.try(&.to_i) || 10

  # ORM level query retries
  settings.query_retries = ENV["RETHINKDB_QUERY_RETRIES"]?.try &.to_i || 10
end

Callbacks

Register callbacks for save, update, create and destroy by setting the corresponding before/after callback handler.

class ModelWithCallbacks < RethinkORM::Base
  attribute address : String
  attribute age : Int32 = 10

  before_create :set_address
  after_update :set_age
  before_destroy do
    self.name = "joe"
  end

  def set_address
    self.address = "23"
  end

  def set_age
    self.age = 30
  end
end

Associations

Set associations with belongs_to, has_many and has_one.

Access children in parent by accessing the method correpsonding to the pluralised child. Children collection method name is generated by dumb pluralisation (appending an s). Optionally set children collection name in has_many by setting collection_name param.

The has_many association requires the belongs_to association on the child. By default, belongs_to creates a secondary index on the foreign key.

class Parent < RethinkORM::Base
  attribute name : String
  has_many Child, collection_name: "children"
end

class Child < RethinkORM::Base
  attribute age : Int32
  belongs_to Parent
  has_many Pet
end

class Pet < RethinkORM::Base
  attribute name : String
  belongs_to Child
end

parent = Parent.new(name: "Phil")
parent.children.empty? # => true

child = Child.new(age: 99)
child.pets.empty? # => true

belongs_to

Parameter		Default
parent_class	The parent class who this class is dependent on
dependent	Sets destroy behaviour. One of :none, :destroy, :delete	:none
create_index	Create a secondary index on the foreign key	true

has_many

Parameter		Default
child_class	The parent class who this class is dependent on
dependent	Sets destroy behaviour. One of :none, :destroy, :delete	:none
collection_name	Define collection name, otherwise collection named through dumb pluralisation	nil

has_one

Parameter		Default
child_class	The parent class who this class is dependent on
dependent	Sets destroy behaviour. One of :none, :destroy, :delete	:none
collection_name	Define collection name, otherwise collection named through dumb pluralisation	nil

Dependency

dependent param in the association definition macros defines the fate of the association on model destruction.
Default is :none, :destroy and :delete ensure destruction of association dependents.

Indexes

Set secondary indexes with secondary_index

Parameter
attribute	defines the field on which to create an index

Changefeeds

Access the changefeed of a document or table through the changes query.
Defaults to watch for events on a table if no id provided.

Parameter		Default
id	id of document to watch for changes	nil

Returns an iterator that emits NamedTuple(value: T, event: Event)

• Changefeed::Event::Deleted events yield the deleted model
• Changefeed::Event::Created events yield the created model
• Changefeed::Event::Updated events yield the updated model

class Game < RethinkORM::Base
  attribute type : String
  attribute score : Int32, default: 0
end

ballgame = Game.create!(type: "footy")

# Observe changes on a single document
spawn do
  Game.changes(ballgame.id).each do |change|
    game = change.value
    puts "looks like the score is #{game.score}" unless game.nil?
  end
end

# Observe changes on a table
spawn do
  Game.changes.each do |change|
    game = change.value
    puts "#{game.type}: #{game.score}" unless game.nil?
    puts "game event: #{change.event}"
  end
end

Validations

Builds on active-model's validation

ensure_unique

Fails to validate if field with duplicate value present in db. If scope is set, the callback/block signature must be a tuple with types matching that of the scope. The field(s) are set with the result of the transform block upon successful validation

Parameter		Default
field	Model attribute on which to guarantee uniqueness
scope	Attributes passed to the transform, defaults to :field	nil
create_index	Whether or not to generate a secondary index	true
callback : T -> T	Optional function to transform field value	nil
block : T -> T	Optional block to transform field value before querying	nil

Timestamps

Adds creates created_at and updated_at attributes.

• updated_at is set through the before_update callback, and initially set in the before_save callback.
• created_at is set through the before_create callback.

The generated timestamp is UTC.

class Timo < RethinkORM::Base
  # Simply include the module
  include RethinkORM::Timestamps

  attribute name : String
end