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I am working on an application that is already deployed to some test and staging systems and various developers workstations. I need to add some additional reference data but i'm not sure how to add it.
Most of the advice says use seed.rb, however my understanding is that this is only run once, when the application is initially deployed. Since we don't want to rebuild the test and staging databases just so that we can add 1 row of reference data, is there another way to add the data?
I'm thinking of using a db migration, is this the correct approach?
Thanks
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If you've ever run rails g migration AddFooToBar and rake db:migrate , you should feel comfortable. Create a migration with rails g seed_migration NameOfMigration . That will create a new file under db/data . Write your changes in the up and down methods, exactly like you would do for a regular migration.
Rails seed files are a useful way of populating a database with the initial data needed for a Rails project. The Rails db/seeds. rb file contains plain Ruby code and can be run with the Rails-default rails db:seed task.
Structure your seed.rb file to allow ongoing creation and updating of data. You are not limited to running a seed file only once and if you think it's only used for initial deployment you will miss out on the flexibility it can offer in setting reference data.
A seed file is just ruby so you can do things like:
user = User.find_or_initialize_by(email: '[email protected]')
user.name = 'Bob'
user.password = 'secret'
user.role = 'manager'
user.save!
This will create new data if it doesn't exist or update the data if it finds some.
If you structure your seed file correctly you can also create and update dependent objects.
I recommend using the bang save to ensure that exceptions are raised in the event that an object cannot be saved. This is the easiest method of debugging the seed.
I use the seedbank gem to provide more structure to my seed data, including setting data per environment, dependent seeds and more.
I don't recommend using migrations for seed data. There is a lack of flexibility (how do you target seed data to just one environment for instance) and no real way to build up a reusable set of data that can be run at any time to refresh a particular environment. You would also have a set of migrations which have no reference to your schema and you would have to create new migrations every time you wanted to generate new or vary current data.
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