```ruby
class AddSlugToTags < ActiveRecord::Migration
  def up
    add_column :tags, :slug, :text, null: false
  end

  def down
    remove_column :tags, :slug
  end
end
```

Remove null constraint on tag slug. SQLite3 did /not/ appreciate that.
user
```ruby
class AddSlugToTags < ActiveRecord::Migration
  def up
    add_column :tags, :slug, :text
  end

  def down
    remove_column :tags, :slug
  end
end
```
assistant