I want to add some category for my Rails post app.
I want them as fixed value so user can choose from the drop down menu the specific category. My migration file looks like this:
class CreateCategories < ActiveRecord::Migration[5.1]
def change
create_table :categories do |t|
t.string :name
t.timestamps
end
end
end
What do I have to do to add some fixed value in my categories model?
You could set constant like NAMES = %w(category1 category2) inside Category model, add inclusion validation and get values for your dropdown like this: Category::NAMES. In this case don't forget to add database index. Obviously you will query posts related to some category.
There is another option though provided by ActiveRecord::Enum. It lets you declare category field right inside Post without Category model at all. If you don't need to manage categories outside the codebase (some admin panel), I would recommend this:
class Post < ActiveRecord::Base
enum category: [:category1, :category2]
end
If you want to add some predefined categories, then this is called "seed data": Migrations and Seed data.
To add initial data after a database is created, Rails has a built-in 'seeds' feature that makes the process quick and easy. This is especially useful when reloading the database frequently in development and test environments. It's easy to get started with this feature: just fill up
db/seeds.rbwith some Ruby code, and runrails db:seed:
Category.create(name: 'category 1')
Category.create(name: 'category 2')
