使用自定义 ActiveRecord::Type（二进制）列时，“has_many through”关联不起作用

Question

I've created the following ActiveRecord type and while has_many associations work well, has_many :through don't:

# app/types/uuid_type.rb
class UuidType < ActiveRecord::Type::Binary
  def serialize(value)
    super(cast_to_uuid(value)&.raw)
  end

  def deserialize(value)
    cast_to_uuid(super(value)).to_s
  end

  def cast_value(value)
    cast_to_uuid(value).to_s
  end

  private

  def cast_to_uuid(value)
    return if value.nil?

    case value.size
    when 16 then UUIDTools::UUID.parse_raw(value) # From `uuidtools` gem
    when 36 then UUIDTools::UUID.parse(value)     # From `uuidtools` gem
    end
  end
end

# app/models/token.rb
class Token < ActiveRecord::Base
  attribute :id, UuidType.new, default: SecureRandom.uuid

  has_many :token_users
  has_many :users, through: :token_users
end

(I've also written an entire code to replicate the issue ).

---

The SQL where clause generated for has_many is similar to the following and works perfectly:

WHERE column = x'4e254953bcdb4793a485ac04131565a7'

While the one generated for has_many :through does not work:

WHERE column = '4e254953-bcdb-4793-a485-ac04131565a7'

It doesn't return any error, but also doesn't return any results .

The problem is that the second one ( has_many :through ) doesn't include the x prefix and also doesn't remove the hyphens (If I manually do that, it solves the issue).

I was able to replicate the issue with both MySQL and SQlite and both Rails 5 and 6 .

Why does the has_many :through relationship not produce the same SQL for a binary type? And how can you get it working so that it does?

Answer 1

It turns out that it was a Rails bug.

I've submitted an issue on the official repo and they've fixed it:

👉 https://github.com/rails/rails/pull/36847

Answer 2

我不确定它是否会有所帮助，但转到 config/initializers/type.rb 并添加

ActiveRecord::Type.register(:token_users, UuidType)