使用多个关系时的 rom-rb 表单验证

Question

我正在尝试 http://rom-rb.org/，但无法弄清楚如何在存在多个源模型的情况下让存在验证通过。我希望以下脚本能够保存一个新的事件和组织者，但它却说 event_name 不存在。

我错过了什么？

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'rom'
  gem 'rom-sql'
  gem 'rom-rails'
  gem 'activemodel'
  gem 'sqlite3'
  gem 'activesupport'
end

require 'rom'
require 'rom-rails'

`rm -Rf /tmp/romtest.sqlite`
ROM.setup(:sql, 'sqlite:///tmp/romtest.sqlite')

class Events < ROM::Relation[:sql]
end

class Organisers < ROM::Relation[:sql]
end

class CreateEvent < ROM::Commands::Create[:sql]
  relation :events
  register_as :create
  result :one

  associates :organiser, key: [:organiser_id, :id]
end

class CreateOrganiser < ROM::Commands::Create[:sql]
  relation :organisers
  register_as :create
  result :one
end

class CreateEventWithOrganiser < ROM::Model::Form
  commands organisers: :create, events: :create

  input do
    attribute :email
    attribute :event_name
  end

  validations do
    validates :event_name, presence: true
  end

  def commit!
    command = organisers.create.with(
      email: email,
    ) >> events.create.with(
      name: event_name,
    )

    command.transaction do
      command.call
    end
  end
end

ROM.finalize
rom = ROM.env
gateway = rom.gateways.fetch(:default)
migration = gateway.migration do
  change do
    create_table :organisers do
      primary_key :id
      column :email, String, null: false
    end

    create_table :events do
      primary_key :id
      column :name, String, null: false
      column :organiser_id, Integer, null: false
    end
  end
end

migration.apply(gateway.connection, :up)

f = CreateEventWithOrganiser.build(
  email:      'test@example.com',
  event_name: 'Test Event'
)

# Unexpectedly fails
f.save
puts f.errors.full_messages
# => "Event name can't be blank"

Answer 1

这是您的脚本的更新版本：

require 'rom'
require 'rom-rails'

`rm -Rf /tmp/romtest.sqlite`
ROM.setup(:sql, 'sqlite:///tmp/romtest.sqlite')

class Events < ROM::Relation[:sql]
end

class Organisers < ROM::Relation[:sql]
end

class CreateEvent < ROM::Commands::Create[:sql]
  relation :events
  register_as :create
  result :one

  associates :organiser, key: [:organiser_id, :id]
end

class CreateOrganiser < ROM::Commands::Create[:sql]
  relation :organisers
  register_as :create
  result :one
end

class CreateEventWithOrganiser < ROM::Model::Form
  inject_commands_for :organisers, :events

  input do
    attribute :email
    attribute :event_name
  end

  validations do
    validates :event_name, presence: true
  end

  def commit!
    validate!

    return if errors.any?

    command = organisers.create.with(
      email: email
    ) >> events.create.with(
      name: event_name
    )

    command.transaction do
      command.call
    end
  end
end

ROM.finalize
rom = ROM.env
gateway = rom.gateways.fetch(:default)
migration = gateway.migration do
  change do
    create_table :organisers do
      primary_key :id
      column :email, String, null: false
    end

    create_table :events do
      primary_key :id
      column :name, String, null: false
      column :organiser_id, Integer, null: false
    end
  end
end

migration.apply(gateway.connection, :up)

f = CreateEventWithOrganiser.build(
  email:      'test@example.com',
  event_name: 'Test Event'
)

puts f.save.result.inspect
# #<ROM::Commands::Result::Success:0x007fa92b589ea0 @value={:id=>1, :name=>"Test Event", :organiser_id=>1}>

它不能与 commands 一起工作的原因是因为此方法将为您的表单生成命令对象并为每个命令设置提供的验证，只有在您使用单个命令时才能正常工作。否则，相同的验证器将用于每个没有意义的命令。当您使用 inject_commands_for 时，它会在未设置验证器的情况下获取您自己的命令，因此您可以自由地自己处理验证。

我认为我们应该停止在命令上设置验证器，这会使您的原始示例工作，但请注意您需要自己调用 validate!。

希望对您有所帮助。

我还创建了一个要点，展示了如何在没有表单的情况下执行相同的操作：https://gist.github.com/solnic/3b68342482cf1414f719

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