Feature: Multi ORM Planning

Here are some of the ideas that need to be fleshed out for Active Admin to support multiple ORMs.

Resource Registration

When a resource is registered, it should instantiate the correct adapter for the given backend. So if an ActiveRecord subclass is registered, it should instantiate an ActiveAdmin::ResourceAdapter::ActiveRecord. (Note class naming is up for discussion still)

The type could also be explicitly passed in.

For example:

ActiveAdmin.register User, :type => :mongoid

Abstract Adapter

Adapters will have to suppor the following:

• Retrieving a collection for the index page. Most of the features required for this are in ActiveAdmin::ResourceController::Collection
  • Sorting
  • Scoping (support for the scope AA dsl method)
  • Scope to (support for the scope_to AA DSL method)
  • Pagination
  • Search / Filtering
• Instantiate and return a new resource
• Create a new resource from params
• Find a specific resource
  • This could include a scope_to or belongs_to AA relationship
• Edit a resource

Libraries can register a new AbstractAdapter subclass and should also be able to specify some logic for when it get's used.

For example:

class MyCustomAdapter < ActiveAdmin::ResourceAdpater::Abstract; end

ActiveAdmin::ResourceAdpater.register :my_custom, MyCustomAdapater do |resource_class|
  # This block get's run if the user does not explicitly pass
  # in the :type option. Return true from it if your adapter should be used
  resource_class.ancestors.include?(ActiveRecord::Base)
end

Abstract Adapter Feature Support

Active Admin supports many features which may not be supported by all ORMs. Initially, the sidebar filtering comes to mind. ORMs should have a way of letting the system know if certain features are enabled on them.

For example:

class SimpleAdapter < ActiveAdmin::ResourceAdapater::Abstract
  def supports_filters?
    false
  end
end

ActiveAdmin.register SomeObj, :type => :simple_adapter do
  filter :name #=> raises an exception since this feature is not support
end