Using the Neo4jrb gem, is it possible to use one transaction across multiple blocks

Question

Using the neo4jrb/neo4j gem (8.x), I know it is possible to run multiple queries inside a single transaction like so

person = Person.find_by(id: person_id)

Neo4j::ActiveBase.run_transaction do |tx|
  person.update(name: 'New name')
  person.update(number: 1)
end

But it possible to open a transaction, and then use that same transaction across multiple blocks. Something like:

person = Person.find_by(id: person_id)

transaction = Neo4j::ActiveBase.new_transaction

transaction.run do |tx|
  person.update(name: 'New name')
end

transaction.run do |tx|
  person.update(number: 1)
end

transaction.close

The reason why this functionality is desirable is because I'm using Neo4jrb inside of a Trailblazer-Operation . The trailblazer operation is broken up into discrete steps which are themselves written as separate methods. I want several of the steps wrapped in a transaction, but, without monkey patching the operation, I don't have the ability to execute some steps inside one transaction block.

Thanks!

Answer 1

So it turns out that my problem has multiple solutions.

While it wasn't immediately apparent to me that this was the case, after a new transaction is created in Neo4jrb, any subsequent queries in that same session are automatically associated with the transaction as long as it remains open.

person = Person.find_by(id: person_id)

transaction = Neo4j::ActiveBase.new_transaction

one = person.update(name: 'New name')

two = person.update(number: 1)

transaction.close

In the above example, both one and two are committed as part of transaction . So this solves my problem.

Another solution to my problem, is that trailblazer-operation has a specific method for wrapping steps in a db transaction block, as documented on Trailblazer's website .

step Wrap ->(*, &block) { Sequel.transaction do block.call end } {
  step Model( Song, :new )
  step Contract::Build( constant: MyContract )
  step Contract::Validate( )
  step Contract::Persist( method: :sync )
}

In the above example, all of the step methods inside step Wrap are called within the scope of the Sequel.transaction block.