SaveResource module

1_preview.rb

# SaveResource предназначен для созданиия записи в БД с nested_attributes (или без них). 
# Особенности:
#  * если у записи уже есть persisted nested records и при обновлении их атрибуты не были переданы, то такие записи будут удалены;
#  * перед сохранением записи в БД, с ней можно выполнить любое действие (например установить дефолтные параметры) с помощью передачи блока в конструктор.

# Примеры вызова:

def create
  update_position = ->(operation) { operation.position = operation.user.positions.first! }
  service = SaveResource::Common.new(Operation, params[:operation], &update_position)

  if service.save
    render json: { operation: service.record.as_json }
  else
    render status: 422, text: "Record #{service.error_record.class} invalid"
  end
end

def update
  service = SaveResource::WithManyNested.new(Kind, params[:kind], :kind_accounts) do |kind|
    kind.parent_accounts.each { |account| kind.kind_accounts.find_or_create_by!(account_id: account.id) }
  end

  if service.save
    render json: { kind: service.record.as_json }
  else
    render status: 422, text: "Record #{service.error_record.class} invalid"
  end
end

base.rb

# frozen_string_literal: true

module SaveResource
  class SaveResourceError < StandardError; end;

  class Base # :nodoc:
    attr_reader :model, :attrs, :record, :block, :error_record

    def initialize(model, attrs, &block)
      @model = model
      @attrs = attrs
      @record = model.find_by(id: attrs[:id])&.lock! || model.new
      @block = block
    end

    def save
      raise NotImplementedError
    end

    private

    def find_or_create
      ActiveRecord::Base.transaction(requires_new: true) do
        record.assign_attributes(attrs)
        record.save(validate: false)

        yield if block_given?
        block&.(record)
        record.save!
      end
    rescue ActiveRecord::RecordInvalid => e
      @error_record = e.record
      false
    end
  end
end

common.rb

# frozen_string_literal: true

module SaveResource
  class Common < Base # :nodoc:
    def save
      find_or_create
    end
  end
end

with_many_nested.rb

# frozen_string_literal: true

module SaveResource
  class WithManyNested < Base # :nodoc:
    attr_reader :association_name, :nested_collection, :persisted_nested_attrs, :new_nested_attrs

    def initialize(model, attrs, association_name, &block)
      super(model, attrs, &block)

      nested_attrs = attrs.delete("#{association_name}_attributes")
      @association_name = association_name
      @nested_collection = record.public_send(association_name)
      @persisted_nested_attrs, @new_nested_attrs = nested_attrs.each_with_object([[], []]) do |attr, acc| 
        (attr[:id] ? acc[0] : acc[1] ) << attr
      end
    end

    def save
      find_or_create do
        update_association_records if persisted_nested_attrs.present?
        create_association_records if new_nested_attrs.present?
      end
    end

    def update_association_records
      persisted_ids = persisted_nested_attrs.map { |attr| attr[:id] }

      nested_collection.where(id: persisted_ids).each do |nested_record|
        attrs = persisted_nested_attrs.find { |attr| attr[:id] == nested_record.id }
        nested_record.update!(attrs)
      end

      delete_unused_association_records(persisted_ids)
    end

    def delete_unused_association_records(ids)
      nested_collection.where.not(id: ids).destroy_all
    end

    def create_association_records
      new_nested_attrs.each { |attrs| nested_collection.create!(attrs) }
    end
  end
end

with_one_nested.rb

# frozen_string_literal: true

module SaveResource
  class WithOneNested < Base # :nodoc:
    attr_reader :nested_attrs, :association_name, :nested_record

    def initialize(model, attrs, association_name, &block)
      super(model, attrs, &block)

      @nested_attrs = attrs.delete("#{association_name}_attributes").with_indifferent_access
      @association_name = association_name
      @nested_record = record.public_send(association_name)
    end

    def save
      find_or_create do
        nested_record.present? ? update_nested_record : create_nested_record
      end
    end

    private

    def update_nested_record
      if nested_attrs[:id] && nested_attrs[:id] != nested_record.id
        raise SaveResourceError, 'Updated record is not match nested attributes'
      end
      nested_record.update!(nested_attrs)
    end

    def create_nested_record
      record.public_send("create_#{association_name}!", nested_attrs)
    end
  end
end