Ruby convert array of active records or objects into array of hashes

Question

I have an object Persons which is an ActiveRecord model with some fields like :name, :age .etc.

Person has a 1:1 relationship with something called Account where every person has an account .

I have some code that does :

   Account.create!(person: current_person)

where current_person is a specified existing Person active record object.

Note : The table Account has a field for person_id and both of them have has_one in the model for each other.

Now I believe we could do something like below for bulk creation :

 Account.create!([{person: person3},{person:: person2} ....])

I have an array of persons but am not sure of the best way to convert to an array of hashes all having the same key.

Basically the reverse of Convert array of hashes to array is what I want to do.

lacostenycoder · Accepted Answer · 2020-04-02 01:17:41Z

3

Why not just loop over your array of objects?

[person1, person2].each{|person| Account.create!(person: person)}

But if for any reason any of the items you loop over fail Account.create! you may be left in a bad state, so you may want to wrap this in an Active Record Transaction.

ActiveRecord::Base.transaction do
  [person1, person2].each{|person| Account.create!(person: person)}
end

answered Apr 2, 2020 at 1:17

lacostenycoder

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3 Comments

Ace McCloud Over a year ago

In my current solution I was looping over , I assumed batching might help run the queries faster which is why I want to use the bulk create API as I think it handles the transaction part you were mentioning for me ??

lacostenycoder Over a year ago

@PrasaanthNeelakandan what data is being written in this loop? How many records to you need to do at a clip? There are other ways to improver performance if that's your goal but that is not what you asked in your question.

Ace McCloud Over a year ago

I want to write about 50 entries of data together , like in batches . The writes just write one single field .

Manoel M. Neto · Accepted Answer · 2020-04-02 05:14:34Z

2

The create method actually persists each hash individually, as shown in the source code, so probably it's not what you are looking for. Either way the following code would do the job:

  Account.create!(persons.map { |person| Hash[:person_id, person.id] })

If you need to create all records in the same database operation and are using rails 6+ you could use the insert_all method.

  Account.insert_all(persons.map { |person| Hash[:person_id, person.id] })

For previous versions of rails you should consider using activerecord-import gem.

  # Combination(1).to_a converts [1, 2, 3] to [[1], [2], [3]]
  Account.import [:person_id], persons.pluck(:id).combination(1).to_a

edited Apr 2, 2020 at 5:14

answered Apr 2, 2020 at 5:02

Manoel M. Neto

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1 Comment

Ace McCloud Over a year ago

Thank you . This seems to be better.

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