MapperSelectors

The MapperSelectors extension type is in charge of mapping the required fields from the API (after having been expanded by the FieldExpansion extension, to tables, associations and columns in the Datastore.

This extension adds the set_selectors method to the controllers, which will be used by the query building (i.e., mapper)extensions to know what fields to select, and join to retrieve the smallest subset of data necessary to satisfy the output fields of the request.

To manually use this extension, include it in a controller with include Praxis::Extensions::MapperSelectors. and define before callbacks on relevant actions that call set_selectors. For example:

before actions: [:index, :show] do |controller|
  controller.set_selectors
end

This exact thing,however, is automatically done for you when you include the MapperPlugin