Class: ROM::Relation

Inherits:
Object
  • Object
show all
Extended by:
AutoCurry, Initializer, Notifications::Listener, Plugins::ClassMethods, ClassInterface, SettingProxy
Includes:
Dry::Core::Memoizable, Pipeline, Commands, Materializable
Defined in:
lib/rom/relation.rb,
lib/rom/relation/name.rb,
lib/rom/relation/wrap.rb,
lib/rom/relation/graph.rb,
lib/rom/compat/relation.rb,
lib/rom/relation/loaded.rb,
lib/rom/relation/curried.rb,
lib/rom/relation/combined.rb,
lib/rom/relation/commands.rb,
lib/rom/relation/composite.rb,
lib/rom/relation/materializable.rb,
lib/rom/relation/class_interface.rb

Overview

Base relation class

Relation is a proxy for the dataset object provided by the gateway. It can forward methods to the dataset, which is why the “native” interface of the underlying gateway is available in the relation

Individual adapters sets up their relation classes and provide different APIs depending on their persistence backend.

Direct Known Subclasses

Memory::Relation

Defined Under Namespace

Modules: ClassInterface, Commands, Materializable Classes: Combined, Composite, Curried, Graph, Loaded, Name, Wrap

Constant Summary collapse

NOOP_OUTPUT_SCHEMA =

Default no-op output schema which is called in `Relation#each`

-> tuple { tuple }.freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Plugins::ClassMethods

plugins, use

Methods included from Initializer

extended

Methods included from ClassInterface

curried, forward

Methods included from Notifications::Listener

subscribe

Methods included from AutoCurry

auto_curried_methods, auto_curry, auto_curry_busy?, auto_curry_guard, extended

Methods included from Pipeline::Operator

#>>

Methods included from Materializable

#first, #one, #one!

Methods included from Commands

#command

Instance Attribute Details

#associations ⇒ Setup::registry (readonly)

Returns Relation associations.

Returns:

  • (Setup::registry) —

    Relation associations



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# File 'lib/rom/relation.rb', line 128

option :associations, default: -> { registry.associations.scoped(config.component.id) }

#auto_map ⇒ TrueClass, FalseClass (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns Whether or not a relation and its compositions should be auto-mapped.

Returns:

  • (TrueClass, FalseClass) —

    Whether or not a relation and its compositions should be auto-mapped



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# File 'lib/rom/relation.rb', line 145

option :auto_map, default: -> { config.auto_map }

#auto_struct ⇒ TrueClass, FalseClass (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns Whether or not tuples should be auto-mapped to structs.

Returns:

  • (TrueClass, FalseClass) —

    Whether or not tuples should be auto-mapped to structs



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# File 'lib/rom/relation.rb', line 150

option :auto_struct, default: -> { config.auto_struct }

#commands ⇒ Commandregistry (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns Command registry.

Returns:

  • (Commandregistry) —

    Command registry



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# File 'lib/rom/relation.rb', line 176

option :commands, default: -> do
  registry.commands.scoped(config.component.id, opts: {adapter: adapter})
end

#config ⇒ Dry::Configurable::Config (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns:

  • (Dry::Configurable::Config) 


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# File 'lib/rom/relation.rb', line 93

option :config, default: -> { self.class.config }

#dataset ⇒ Object (readonly)

Returns dataset used by the relation provided by relation's gateway.

Returns:

  • (Object) —

    dataset used by the relation provided by relation's gateway



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# File 'lib/rom/relation.rb', line 124

option :dataset, default: -> { datasets.infer(config.component.id) }

#datasets ⇒ registry (readonly)

Returns Relation associations.

Returns:



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# File 'lib/rom/relation.rb', line 119

option :datasets, default: -> { registry.datasets.scoped(config.component.id, config: config) }

#inflector ⇒ Dry::Inflector (readonly)

Returns The default inflector.

Returns:

  • (Dry::Inflector) —

    The default inflector



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# File 'lib/rom/relation.rb', line 107

option :inflector, default: -> { config.component.inflector }

#input_schema ⇒ Object#[] (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns tuple processing function, uses schema or defaults to Hash[].

Returns:

  • (Object#[]) —

    tuple processing function, uses schema or defaults to Hash[]



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# File 'lib/rom/relation.rb', line 133

option :input_schema, default: -> { schema.to_input_hash }

#mappers ⇒ registry (readonly)

Returns an optional mapper registry (empty by default).

Returns:

  • (registry) —

    an optional mapper registry (empty by default)



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# File 'lib/rom/relation.rb', line 159

option :mappers,
-> mappers {
  if mappers.is_a?(Hash)
    registry.mappers
      .scoped(config.component.id, opts: {adapter: config.component.adapter})
      .import(mappers)
  else
    mappers
  end
},
default: -> {
  registry.mappers.scoped(config.component.id, opts: {adapter: adapter})
}

#meta ⇒ Hash (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns Meta data stored in a hash.

Returns:

  • (Hash) —

    Meta data stored in a hash



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# File 'lib/rom/relation.rb', line 183

option :meta, reader: true, default: -> { EMPTY_HASH }

#name ⇒ Name (readonly)

Returns The relation name.

Returns:

  • (Name) —

    The relation name



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# File 'lib/rom/relation.rb', line 98

option :name, default: -> { Name[config.component.id, config.component.dataset] }

#output_schema ⇒ Object#[] (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns tuple processing function, uses schema or defaults to NOOP_OUTPUT_SCHEMA.

Returns:

  • (Object#[]) —

    tuple processing function, uses schema or defaults to NOOP_OUTPUT_SCHEMA



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# File 'lib/rom/relation.rb', line 138

option :output_schema, default: lambda {
  schema.any?(&:read?) ? schema.to_output_hash : NOOP_OUTPUT_SCHEMA
}

#registry ⇒ registry (readonly)

Returns Registry::Root with runtime dependency resolving.

Returns:

  • (registry) —

    Registry::Root with runtime dependency resolving



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# File 'lib/rom/relation.rb', line 102

option :registry, default: -> { self.class.registry(config: config) }

#schema ⇒ Setup::registry (readonly)

Returns The canonical schema.

Returns:

  • (Setup::registry) —

    The canonical schema



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# File 'lib/rom/relation.rb', line 115

option :schema, default: -> { schemas.infer(config.component.id) }

#schemas ⇒ Setup::registry (readonly)

Returns Relation schemas.

Returns:

  • (Setup::registry) —

    Relation schemas



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# File 'lib/rom/relation.rb', line 111

option :schemas, default: -> { registry.schemas.scoped(config.component.id, config: config) }

#struct_namespace(ns) ⇒ Relation (readonly)

Return a new relation configured with the provided struct namespace

Parameters:

  • ns (Module) —

    Custom namespace module for auto-structs

Returns:



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# File 'lib/rom/relation.rb', line 155

option :struct_namespace, reader: false, default: -> { config.struct_namespace }

Class Method Details

.inherited(klass) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/rom/relation.rb', line 59

def self.inherited(klass)
  super

  adapter = config.component.adapter

  klass.configure do |config|
    # Relations that inherit from an adapter subclass are not considered abstract anymore
    # You can override it later inside your class' config of course
    if adapter
      config.component.abstract = false

      # Use klass' name to set defaults
      #
      # ie `Relations::Users` assumes :users id and a corresponding dataset (table in case of SQL)
      #
      # TODO: make this behavior configurable?
      #
      if klass.name
        config.component.id = config.component.inflector.component_id(klass.name).to_sym
        config.component.dataset = config.component.id
      else
        config.component.id = :anonymous
      end
    end
  end
end

.new(dataset = nil, **opts) ⇒ Object 



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# File 'lib/rom/relation.rb', line 186

def self.new(dataset = nil, **opts)
  if dataset
    super(**opts, dataset: dataset)
  else
    super(**opts)
  end
end

.setting_mapping ⇒ Object 



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# File 'lib/rom/compat/relation.rb', line 11

def setting_mapping
  @setting_mapping ||= {
    auto_map: [],
    auto_struct: [],
    struct_namespace: [],
    wrap_class: [],
    adapter: [:component, :adapter],
    gateway: [:component, :gateway],
    schema_class: [:schema, :constant],
    schema_dsl: [:schema, :dsl_class],
    schema_attr_class: [:schema, :attr_class],
    schema_inferrer: [:schema, :inferrer]
  }.freeze
end

.view_methods ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

This is used by the deprecated command => relation view delegation syntax



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# File 'lib/rom/compat/relation.rb', line 31

def self.view_methods
  ancestor_methods = ancestors.reject { |klass| klass == self }
    .map(&:instance_methods).flatten(1)

  instance_methods - ancestor_methods + auto_curried_methods.to_a
end

Instance Method Details

#[](name) ⇒ Attribute

Return schema attribute

Examples:

accessing canonical attribute

users[:id]
# => #<ROM::SQL::Attribute[Integer] primary_key=true name=:id source=ROM::Relation::Name(users)>

accessing joined attribute

tasks_with_users = tasks.join(users).select_append(tasks[:title])
tasks_with_users[:title, :tasks]
# => #<ROM::SQL::Attribute[String] primary_key=false name=:title source=ROM::Relation::Name(tasks)>

Returns:



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# File 'lib/rom/relation.rb', line 208

def [](name)
  schema[name]
end

#adapter ⇒ Symbol

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns The wrapped relation's adapter identifier ie :sql or :http.

Returns:

  • (Symbol) —

    The wrapped relation's adapter identifier ie :sql or :http



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# File 'lib/rom/relation.rb', line 556

def adapter
  config.component.adapter
end

#as(aliaz) ⇒ Relation

Return a new relation with an aliased name

Examples:

users.as(:people)

Parameters:

  • aliaz (Symbol) —

    Aliased name

Returns:



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# File 'lib/rom/relation.rb', line 549

def as(aliaz)
  with(name: name.as(aliaz))
end

#attr_ast ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/rom/relation.rb', line 468

def attr_ast
  schema.map(&:to_read_ast)
end

#auto_map? ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns:

  • (Boolean) 


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# File 'lib/rom/relation.rb', line 481

def auto_map?
  (auto_map || auto_struct) && !meta[:combine_type]
end

#auto_struct? ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns:

  • (Boolean) 


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# File 'lib/rom/relation.rb', line 486

def auto_struct?
  auto_struct && !meta[:combine_type]
end

#call ⇒ Relation::Loaded

Loads a relation

Returns:



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# File 'lib/rom/relation.rb', line 355

def call
  Loaded.new(self)
end

#combine(*associations) ⇒ Relation #combine(*associations, **nested_associations) ⇒ Relation #combine(associations) ⇒ Relation

Combine with other relations using configured associations

Overloads:

  • #combine(*associations) ⇒ Relation

    Examples:

    users.combine(:tasks, :posts)

    Parameters:

    • *associations (Array<Symbol>) —

      A list of association names

  • #combine(*associations, **nested_associations) ⇒ Relation

    Examples:

    users.combine(:tasks, posts: :authors)

    Parameters:

    • *associations (Array<Symbol>) —

      A list of association names

    • *nested_associations (Hash) —

      A hash with nested association names

  • #combine(associations) ⇒ Relation

    Examples:

    users.combine(posts: [:authors, reviews: [:tags, comments: :author])

    Parameters:

    • *associations (Hash) —

      A hash with nested association names

Returns:



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# File 'lib/rom/relation.rb', line 255

def combine(*args)
  combine_with(*nodes(*args))
end

#combine_with(*others) ⇒ Relation::Graph

Composes with other relations

Parameters:

  • others (Array<Relation>) —

    The other relation(s) to compose with

Returns:



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# File 'lib/rom/relation.rb', line 266

def combine_with(*others)
  Combined.new(self, others)
end

#curried? ⇒ false

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns if this relation is curried

Returns:

  • (false) 


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# File 'lib/rom/relation.rb', line 373

def curried?
  false
end

#each {|Hash| ... } ⇒ Enumerator

Yields relation tuples

Every tuple is processed through Relation#output_schema, it's a no-op by default

Yields:

  • (Hash)

Returns:

  • (Enumerator) —

    if block is not provided



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# File 'lib/rom/relation.rb', line 221

def each(&block)
  return to_enum unless block_given?

  if auto_map?
    mapper.(dataset.map { |tuple| output_schema[tuple] }).each(&block)
  else
    dataset.each { |tuple| yield(output_schema[tuple]) }
  end
end

#eager_load(assoc) ⇒ Relation

Return a graph node prepared by the given association

Parameters:

  • assoc (Association) —

    An association object

Returns:



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# File 'lib/rom/relation.rb', line 304

def eager_load(assoc)
  relation = assoc.prepare(self)

  if assoc.override?
    relation.(assoc)
  else
    relation.preload_assoc(assoc)
  end
end

#foreign_key(name) ⇒ Symbol

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Return a foreign key name for the provided relation name

Parameters:

  • name (Name) —

    The relation name object

Returns:

  • (Symbol) 


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# File 'lib/rom/relation.rb', line 576

def foreign_key(name)
  attr = schema.foreign_key(name.dataset)

  if attr
    attr.name
  else
    :"#{inflector.singularize(name.dataset)}_id"
  end
end

#gateway ⇒ Symbol

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Return name of the source gateway of this relation

Returns:

  • (Symbol) 


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# File 'lib/rom/relation.rb', line 565

def gateway
  config.component.gateway
end

#graph? ⇒ false

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns if this relation is a graph

Returns:

  • (false) 


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# File 'lib/rom/relation.rb', line 382

def graph?
  false
end

#map_to(klass, **opts) ⇒ Relation

Return a new relation that will map its tuples to instances of the provided class

Examples:

users.map_to(MyUserModel)

Parameters:

  • klass (Class) —

    Your custom model class

Returns:



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# File 'lib/rom/relation.rb', line 535

def map_to(klass, **opts)
  with(opts.merge(auto_map: false, auto_struct: true, meta: {model: klass}))
end

#map_with(*mappers) ⇒ Relation::Composite #map_with(*mappers, auto_map: true) ⇒ Relation::Composite

Maps relation with custom mappers available via registry

When `auto_map` is enabled, your mappers will be applied after performing default auto-mapping. This means that you can compose complex relations and have them auto-mapped, and use much simpler custom mappers to adjust resulting data according to your requirements.

Overloads:

  • #map_with(*mappers) ⇒ Relation::Composite

    Map tuples using registered mappers

    Examples:

    users.map_with(:my_mapper, :my_other_mapper)

    Parameters:

    • mappers (Array<Symbol>) —

      A list of mapper identifiers

  • #map_with(*mappers, auto_map: true) ⇒ Relation::Composite

    Map tuples using custom registered mappers and enforce auto-mapping

    Examples:

    users.map_with(:my_mapper, :my_other_mapper, auto_map: true)

    Parameters:

    • mappers (Array<Symbol>) —

      A list of mapper identifiers

Returns:



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# File 'lib/rom/relation.rb', line 521

def map_with(*names, **opts)
  super(*names).with(opts)
end

#mapper ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/rom/relation.rb', line 491

def mapper
  mappers[to_ast]
end

#meta_ast ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/rom/relation.rb', line 473

def meta_ast
  meta = self.meta.merge(dataset: name.dataset, alias: name.aliaz,
                         struct_namespace: options[:struct_namespace])
  meta[:model] = false unless auto_struct? || meta[:model]
  meta
end

#new(dataset, **new_opts) ⇒ Object

Return a new relation with provided dataset and additional options

Use this method whenever you need to use dataset API to get a new dataset and you want to return a relation back. Typically relation API should be enough though. If you find yourself using this method, it might be worth to consider reporting an issue that some dataset functionality is not available through relation API.

Examples:

with a new dataset

users.new(users.dataset.some_method)

with a new dataset and options

users.new(users.dataset.some_method, other: 'options')

Parameters:

  • dataset (Object)
  • new_opts (Hash) —

    Additional options



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# File 'lib/rom/relation.rb', line 422

def new(dataset, **new_opts)
  opts =
    if new_opts.empty?
      options
    elsif new_opts.key?(:schema)
      options.merge(new_opts).reject { |k, _| k == :input_schema || k == :output_schema }
    else
      options.merge(new_opts)
    end

  self.class.new(**opts, dataset: dataset)
end

#node(name) ⇒ Relation

Create a graph node for a given association identifier

Parameters:

Returns:



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# File 'lib/rom/relation.rb', line 291

def node(name)
  assoc = associations[name]
  other = assoc.node
  other.eager_load(assoc)
end

#nodes(*args) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/rom/relation.rb', line 271

def nodes(*args)
  args.reduce([]) do |acc, arg|
    case arg
    when Symbol
      acc << node(arg)
    when Hash
      acc.concat(arg.map { |name, opts| node(name).combine(opts) })
    when Array
      acc.concat(arg.map { |opts| nodes(opts) }.reduce(:concat))
    end
  end
end

#preload_assoc(assoc, other) ⇒ Relation::Curried

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Preload other relation via association

This is used internally when relations are composed

Returns:



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# File 'lib/rom/relation.rb', line 321

def preload_assoc(assoc, other)
  assoc.preload(self, other)
end

#schema? ⇒ TrueClass, FalseClass

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns true if a relation has schema defined

Returns:

  • (TrueClass, FalseClass) 


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# File 'lib/rom/relation.rb', line 400

def schema?
  !schema.empty?
end

#to_a ⇒ Array<Hash>

Materializes a relation into an array

Returns:

  • (Array<Hash>) 


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# File 'lib/rom/relation.rb', line 364

def to_a
  to_enum.to_a
end

#to_ast ⇒ Array

Returns AST for the wrapped relation

Returns:

  • (Array) 


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# File 'lib/rom/relation.rb', line 463

def to_ast
  [:relation, [name.relation, attr_ast, meta_ast]]
end

#with(opts) ⇒ Relation

Returns a new instance with the same dataset but new options

Examples:

users.with(output_schema: -> tuple { .. })

Parameters:

  • opts (Hash) —

    New options

Returns:



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# File 'lib/rom/relation.rb', line 447

def with(opts)
  new_options =
    if opts.key?(:meta)
      opts.merge(meta: meta.merge(opts[:meta]))
    else
      opts
    end

  new(dataset, **options, **new_options)
end

#wrap(*names) ⇒ Wrap

Wrap other relations using association names

Examples:

tasks.wrap(:owner)

Parameters:

  • names (Array<Symbol>) —

    A list with association identifiers

Returns:



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# File 'lib/rom/relation.rb', line 335

def wrap(*names)
  wrap_around(*names.map { |n| associations[n].wrap })
end

#wrap? ⇒ false

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Return if this is a wrap relation

Returns:

  • (false) 


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# File 'lib/rom/relation.rb', line 391

def wrap?
  false
end

#wrap_around(*others) ⇒ Relation::Wrap

Wrap around other relations

Parameters:

  • others (Array<Relation>) —

    Other relations

Returns:



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# File 'lib/rom/relation.rb', line 346

def wrap_around(*others)
  wrap_class.new(self, others)
end