May 05, 2010 00:31
Posted by Jeremy Durham
New gem - Seed
I pushed a new repository to Github and a new gem to Gemcutter. It’s called Seed.
Seed is (another) gem designed to deal with seeding databases.
The main advantage of using Seed is that when creating a seed, or retrieving a seed, an error is throw if you attempt to overwrite a seed or retrieve a non-existent seed. The goal is to make you care about your seed data, and ensure that you’re not overwriting existing seeds or trying to make an association between a seed and a non-existent seed.
How does it work?
Role.seed(:system_administrator, :role => 'system_administrator')
User.seed(:jdurham, :login => 'jdurham', :roles => [Role.seed(:system_administrator])
if you like blocks, we’ve also got those covered:
Role.seed(:system_administrator) do |role|
role.role = 'system_administrator'endUser.seed(:jdurham) do |user|
user.login = 'jdurham'user.roles = [Role.seed(:system_administrator)]
endThis will create a Role seed, named “system_administrator”, which we will reused in other seeds. That way, when looking at another seed, it’s very obvious what associated data it has.
Overplanting not allowed
Later on, if I decide I want to create a new seed and I do:
Role.seed(:system_administrator, :role => 'admin')
This will raise an exception, because there will be an ambiguity issue. I’m trying to create another seed named system_administrator.
Trying to get a seed that never existed
User.seed(:normal_user, :roles => [Role.seed(:user)])
This will raise an exception because it doesn’t make sense to try to associate a user with a seed that doesn’t exist.
Great, I’ve got seed data. Now, how do I load it?
Seed comes with a rake task that extends the built-in rake db:seed functionality. In your Rakefile add:
require 'seed/task'Now, create a db/seeds directory and add a file; for example, development.rb to that directory. Once you do, you’ll automatically have a rake task that can be invoked as follows:
rake db:seed:development
Hopefully you find Seed useful. We’ve been using it in production for a little while and it’s been working well.
5 Comments
May 5, 2010
An appropriate time of year to announce your seed gem. Looking good, but I am curious how foreign key references work when there is a validation enforced in the model?
May 7, 2010
The specs have a few examples of create seeds with validations and associations, so I would refer to those.
Under the covers, seed uses .create! to generate the seed, so anything you can do with .create you can do with seed.
The one edge case to this is protected attributes. In order to set attributes that are protected (attr_protected or not listed as attr_accessible) is to use the block syntax. There are also specs to explain this behavior.
August 16, 2010
Havent read the code yet. Does Seed support loading seed data from txt or yaml files?
August 19, 2010
@ruby developr: The seed data is loaded from .rb files, similar to the built in seeds support in Rails 2.3.×. This gem is more of an extension that adds “seed groups” and some validation to prevent overwriting data and orphaned data.
May 4, 2011
I put together a gem seedbank https://github.com/james2m/seedbank to parse db/seeds/* and create seed tasks for each. So I could have common seeds which get supplemented by seeds for each environment.
This seems like a good complement as I find the most effort now goes into the “if it’s already seeded don’t overwrite it of if it’s seeded but needs updating” problems. I hadn’t attempted to resolve these as I didn’t want to pollute the ActiveRecord::Base, but I like your approach of only doing so in the rake task when seeding is being run.
I often find the call for minor tweaks to seeds and would like to be able to update those seeds with just one rake task. Is your policy to never update in place?
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