CODEWITHSUNDEEP
ruby-on-railsactiverecordtransactions
svoop
svoop

Reputation: 3454

"transaction do" without explicit receiver

According to the docs, in Rails models, transactions are made on either classes descending from ActiveRecord::Base or any instance of such a class. Some blog posts on the subject list the following alternatives:

However, I'm missing another variation on this list: How about just transaction do within model.rb?

class User < ApplicationRecord
  def foo
    transaction do
      # do stuff
    end
  end
end

Am I right to assume, that the self. is not really necessary since in the scope of a model instance method, self is always the model instance by default?

Upvotes: 0

Views: 366

Answers (1)

max
max

Reputation: 102230

In Ruby the implicit recipient in an instance method is always the instance:

class Thing
  def foo
    inspect
  end
end

irb(main):026:0> Thing.new.foo
=> "#<Thing:0x007fde95955828>"

Am I right to assume, that the self. is not really necessary since in the scope of a model instance method, self is always the model instance by default?

There is always an implicit recipient (self) in ruby. What it is depends on the context. In class methods its the class. Its "main" (the global object) if you are not in a class or module.

class Foo
  inspect
end
# => "Foo"

def foo
  inspect
end
# => "main"

You only have to explicitly use self where there is a need to disambiguate (like for example self.class). But there are many situations where it can help the readability of your code.

All of the options above are pretty much functionally equivalent:

  • ActiveRecord::Base.transaction connects to the DB for that environment from database.yml or ENV["DATABASE_URL"].
  • User.transaction or class.transaction can be used if you want to have different connections per model class or just don't like typing. All it really does is connection.transaction(options, &block).
  • The instance level self.transaction or @user.transaction just proxies to the class method. All it really does is self.class.transaction(options,&block);

Upvotes: 0

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