Class: Blueprinter::AssociationExtractor

Inherits:
Extractor
  • Object
show all
Defined in:
lib/api_blocks/blueprinter/association_extractor.rb

Overview

Monkey-patch Blueprinter::AssociationExtractor to use ‘batch-loader` gem in order to avoid n+1 queries when serializing associations.

This does not support associations defined using a ‘proc` as `options`

Instance Method Summary collapse

Instance Method Details

#extract(association_name, object, local_options, options = {}) ⇒ Object 



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# File 'lib/api_blocks/blueprinter/association_extractor.rb', line 12

def extract(association_name, object, local_options, options = {})
  if !options.fetch(:batch, true)
    return original_extract(association_name, object, local_options, options)
  end

  association = object.association(association_name)

  if association.is_a?(ActiveRecord::Associations::HasManyThroughAssociation)
    return original_extract(association_name, object, local_options, options)
  end

  if options[:blueprint].is_a?(Proc)
    raise "Cannot load blueprints with a `proc` blueprint option with batch-loader"
  end

  join_key = association.reflection.join_keys
  association_id = object.send(join_key.foreign_key)
  association_klass = association.reflection.class_name

  default_value = case association
                  when ActiveRecord::Associations::HasManyAssociation
                    []
                  end

  view = options[:view] || :default
  scope = if options[:block].present?
    options[:block].call(object, local_options)
  else
    {}
  end

  BatchLoader.for(association_id).batch(
    default_value: default_value,
    key: [association_name, association_klass, view, options[:blueprint], scope],
  ) do |ids, loader, args|
    model = association_klass.safe_constantize
    scope = args[:key].last

    case association
    when ActiveRecord::Associations::HasManyAssociation
      model.where(join_key.key => ids).merge(scope).each do |record|
        loader.call(record.send(join_key.key)) do |memo|
          memo << render_blueprint(record, local_options, options)
        end
      end
    when ActiveRecord::Associations::HasOneAssociation
      model.where(join_key.key => ids).merge(scope).each do |record|
        loader.call(
          record.send(join_key.key),
          render_blueprint(record, local_options, options)
        )
      end
    when ActiveRecord::Associations::BelongsToAssociation
      model.where(join_key.key => ids).merge(scope).each do |record|
        loader.call(
          record.id,
          render_blueprint(record, local_options, options)
        )
      end
    else
      raise "unsupported association kind #{association.class.name}"
    end
  end
end

#original_extract ⇒ Object 



10
 
# File 'lib/api_blocks/blueprinter/association_extractor.rb', line 10

alias_method :original_extract, :extract