How to convert array of ActiveRecord models to CSV?

Question

I got an array of ActiveRecord models that I wish to convert to a CSV. I tried researching gems like FasterCSV, but they just seem to work with strings and arrays, not Activ

Answer 1

This might be off the original question but solve the problem. If you plan to make all or some of your Active Record models be able to convert to csv, you can use ActiveRecord concern. An example is shown below

module Csvable
  extend ActiveSupport::Concern 

  class_methods do
    def to_csv(*attributes)
      CSV.generate(headers: true) do |csv| 
        csv << attributes 

        all.each do |record| 
          csv << attributes.map { |attr| record.send(attr) }
        end 
      end
    end
  end
end

The attribute provided will be used as the header for the CSV and it is expected that this attribute corresponds to methods name in the included class. Then you can include it in any ActiveRecord class of your choice, in this case, the User class

class User 
  include Csvable 

end

Usage

User.where(id: [1, 2, 4]).to_csv(:id, :name, :age)

Note: This only works for ActiveRecord relation and not for arrays

Answer 2

with julia_builder you can configure a csv export pretty easily.

class UserCsv < Julia::Builder
  # specify column's header and value
  column 'Birthday', :dob
  # header equals 'Birthday' and the value will be on `user.dbo`

  # when header and value are the same, no need to duplicate it.
  column :name
  # header equals 'name', value will be `user.name`

  # when you need to do some extra work on the value you can pass a proc.
  column 'Full name', -> { "#{ name.capitalize } #{ last_name.capitalize }" }

  # or you can pass a block
  column 'Type' do |user|
    user.class.name
  end
end

and then

users = User.all
UserCsv.build(users)