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Populate an Active Record database with mass insertion.


Rails 3 support is currently being worked on. Stay tuned.

In Rails 2, install the gem.

gem install populator

And then load it in a rake task or elsewhere.

require "populator"


This gem adds a “populate” method to all Active Record models. Pass the number of records you want to create along with a block. In the block you can set the column values for each record.

Person.populate(3000) do |person|
  person.first_name = "John"
  person.last_name = "Smith"

This will do a mass insert into the database so it is very fast. The person object contains the “id” so you can set up associations.

Person.populate(3000) do |person|
  person.first_name = "John"
  person.last_name = "Smith"
  Project.populate(30) do |project|
    project.person_id = person.id

That will create 30 projects for each person.

Passing a range or array of values will randomly select one.

Person.populate(1000..5000) do |person|
  person.gender = ['male', 'female']
  person.annual_income = 10000..200000

This will create 1000 to 5000 men or women with the annual income between 10,000 and 200,000.

You can pass a :per_query option to limit how many records are saved per query. This defaults to 1000.

Person.populate(2000, :per_query => 100)

If you need to generate fake data, there are a few methods to do this.

Populator.words(3) # generates 3 random words separated by spaces
Populator.words(10..20) # generates between 10 and 20 random words
Populator.sentences(5) # generates 5 sentences
Populator.paragraphs(3) # generates 3 paragraphs

For fancier data generation, try the Faker gem.


For performance reasons, this gem does not use actual instances of the model. This means validations and callbacks are bypassed. It is up to you to ensure you’re adding valid data.


Problems or questions? Add an issue on GitHub or fork the project and send a pull request.

See spec/README for instructions on running specs.

Special Thanks

Special thanks to Zach Dennis for his ar-extensions gem which some of this code is based on. Also many thanks to the contributors. See the CHANGELOG for the full list.