Can FactoryBot generate factories after your models have been created?

When including the factory_bot_rails gem in your dev and test blocks in Gemfile, rails will generate factories automatically when your models are generated.

Is there a way to generate factories after your models have been generated?

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Note: FactoryBot was previously named FactoryGirl

First thing, look at the source project to find out how it was implemented:

https://github.com/thoughtbot/factory_bot_rails/blob/master/lib/generators/factory_bot/model/model_generator.rb

After that, try to guess how it works:

rails g factory_bot:model Car name speed:integer

The result is:

create  test/factories/cars.rb

And the content:

# Read about factories at https://github.com/thoughtbot/factory_girl

FactoryBot.define do
   factory :car do
     name "MyString"
     speed 1
   end
end

Remember, when you use rails g, you can always undo it, with rails d

rails d factory_bot:model Car name speed:integer

Note: FactoryBot was previously named FactoryGirl

The --fixture-replacement option will let you tell rails what to generate for building test data. You can set this as a default in your config/application.rb file, like so:

config.generators do |g|
  g.fixture_replacement :factory_bot, suffix_factory: 'factory'
end

Source: https://github.com/thoughtbot/factory_bot_rails/blob/master/features/fixture_replacement_config.feature#L21

I have a gem for exactly this https://github.com/markburns/to_factory

This works for me using rails g factory_bot:model User either running the command or just puts'ing the command out. You do still have to fill in the value.

@run_command        = true
@force              = true
@columns_to_ignore  = %w[id created_at update_at]
@tables_to_ignore = %w[schema_migrations ar_internal_metadata]
tables = ActiveRecord::Base.connection.tables.reject{|t| (@tables_to_ignore || []).include?(t)}

tables.each do |table|
  klass = table.singularize.camelcase.constantize
    command = "rails g factory_bot:model #{klass.to_s} #{klass.columns.reject do |c|
      (@columns_to_ignore || []).include?(c.name)
    end.map do |d|
      "#{d.name}:#{d.sql_type == 'jsonb' ? 'json' : d.type}"
  end.join(' ')}"
  command << ' --force' if @force
  puts command
  puts %x{#{command}} if @run_command
  puts (1..200).to_a.map{}.join('-')
end

This is not an answer, but since I cannot comment yet: I think you can use this to solve part of your problem. You can use a gem called schema_to_scaffold to generate a factory_girl:model command string. It outputs:

rails generate factory_girl:model users fname:string lname:string bdate:date email:string encrypted_password:string

from your schema.rb or your renamed schema.rb.

Check here or here

Configure Factory Bot as the fixture replacement so you do not have to create factories manually.

In config/application.rb:

config.generators do |g|
  g.test_framework :rspec, fixture: true
  g.fixture_replacement :factory_bot, dir: 'spec/factories'
end

For more: https://github.com/thoughtbot/factory_bot_rails/blob/master/features/fixture_replacement_config.feature

Not exactly related.

I also built a gem to build factory from existing data.

Hopefully, it can help you speed up the process a bit......

puts FactoryBotFactory.build(User.new, file_path: 'spec/factories/user.rb')
puts FactoryBotFactory.build(User.last, file_path: 'spec/factories/user.rb')

# example output from User.new
FactoryBot.define do
  factory :user, class: User do
    id { nil }
    name { nil }
    created_at { nil }
    updated_at { nil }
    display_name { nil }
    image_url { nil }
    is_active { true }
  end
end

You can also configure customize converter if you need to built fake data.

Some good answers here, but another option is to use stepford. For some projects that use schemas that have foreign key constraints, the deep_* methods, etc. might help, and it is a simple way to generate factories via command-line.