Repositories

The cornerstones of Uchi are the repositories. This is where you configure what parts of your models you want to expose and how to do it.

Models

There’s a one-to-one mapping between a repository and a model. So if you have a User model that you want to include in Uchi, you must have a User repository as well.

How to configure the repository for a controller

Each repository is exposed to the user via a controller. The controller name is the pluralized param key of the model, so a USB model is routed to Uchi::UsbsController.

For the vast majority of cases Uchi guesses the repository to use for a given controller by singularizing the controller name, ie Uchi::UsbsController uses Uchi::Repositories::Usb. In case you have special requirements, you can override the private #repository_class method in your controller:

module Uchi
  class UsbsController < Uchi::RepositoryController
    private

    def repository_class
      Uchi::Repositories::USB
    end
  end
end

Default sort order

Lists of records in a repository are by default sorted ascending by the model’s primary key. To customize the default sort order, which is used when a user hasn’t explicitly chosen to sort by a specific field, you can create a default_sort_order method in the repository:

module Uchi
  module Repositories
    class Customer < Repository
      def default_sort_order
        SortOrder.new(:name, :desc)
      end
    end
  end
end

default_sort_order should return a Uchi::SortOrder.

The sort order is only applied if the repository has a field with the same name as the sort column. If #fields doesn’t include a field named :name, the example above leaves the records unsorted. The same applies to the default sort order if there is no field for the primary key.

Avoiding n+1

To avoid n+1 performance issues on your index pages and other lists, you can set up includes for the repository.

module Uchi
  module Repositories
    class User < Repository
      def includes
        [:account]
      end
    end
  end
end

See https://api.rubyonrails.org/classes/ActiveRecord/QueryMethods.html#method-i-includes for details.

Customizing the title of a record

When a model is rendered in the UI, we call the #title method on the repository for that model. By default #title returns the value of the first of the following methods that exists on the model:

1. #title
2. #name
3. #to_s

If none of those return a suitable value for your model, you can override the #title method in your repository to return a better value:

  def title(record)
    return nil unless record

    record.original_title
  end