A set of tools to tidy up rails seeds.rb files.

Dibber has two compoments:


Seeder is designed to simplify the process of pulling attributes from YAML files, and populating ActiveRecord objects with those attributes.


ProcessLog provides Seeder with a simple before and after reporting tool.


Add this to your Gemfile:

gem 'dibber'

Rails Examples

You have a rails app with a ‘Thing` model, and you want to seed it with some things. `Thing` instances have the attributes `name`, `colour`, `size`. You have a YAML file `db/seeds/things.yml` that looks like this:

  colour: red
  size: large

  colour: blue
  size: small

Add this to your ‘db/seeds.rb’

Seeder = Dibber::Seeder
Seeder.seed Thing
puts Seeder.report

Then run ‘rake db:seed`

Seeder will create two new things.

You’ll then be able to do this:

thing = Thing.find_by(name: 'foo')
thing.colour    ---> 'red'

Pass the name of the class to seed

All of these are equivalent commands

Dibber::Seeder.seed Thing
Dibber::Seeder.seed :thing
Dibber::Seeder.seed 'Thing'

Dynamic content

Seed content can also have dynamic content added via ERB. For example, if you want the colour of the ‘foo` thing to be either ’red’ or ‘yellow’, change ‘db/seeds/things.yml` to

  colour: <%= ['red', 'yellow'].sample %>
  size: large

Then when we run ‘Dibber::Seeder.seed :thing` a new `Thing` will be created with the colour set to either ’red’ or ‘yellow’.

Using blocks with Seeder

If you pass a block to ‘.seed` the block will be called on each object being built as it is created or updated.

So for example, if Thing has attributes ‘size` and `big` the following is possible:

Dibber::Seeder.seed(:thing) do |thing|
  thing.big = thing.attributes['size'] > 10


Seeder.report outputs a report detailing start and end time, and a log of how the number of things has changed

Overwriting existing entries

Seeder#build will not overwrite existing data unless directed to do so.

thing.update_attribute(:colour, 'black')
Seeder.seed :thing
thing.reload.colour  ----> 'black'

Seeder.seed(:thing, overwrite: true)
thing.reload.colour  ----> 'red'

Using alternative class and field name mappings

Seeder.seed calls Seeder#build to build the objects defined in the seed files. You can call the build method directly if your seed file names do not match the class name:

Seeder.new(Thing, 'other_things.yml').build

Outside Rails

Dibber can be used outside of Rails, but in this case you will need to specify the location of the seed files.

Seeder.seeds_path = "some/path/to/seeds"

You can also use this technique in Rails if you want to put your seed files in a folder other than ‘db/seeds’

More examples

Take a look at test/examples/seeds.rb for some more usage examples.

If you clone this app, you can run this example at the project root:

ruby test/examples/seeds.rb

There is also an example of process log usage:

ruby test/examples/process_logs.rb