Refactor DocumentPresenter#fields to use generic logic applicable for…

… different types of field displays

app/presenters/blacklight/document_presenter.rb

@@ -79,10 +79,8 @@ def display_type(base_name = nil, default: nil)
 
       fields += ['format'] if fields.empty? # backwards compatibility with the old default value for display_type_field
 
-      display_type = fields.lazy.map { |field| field_presenter(field_config(field)) }.detect(&:any?)&.values
-      display_type ||= Array(default) if default
-
-      display_type || []
+      display_type = fields.lazy.map { |field| field_presenter(display_fields[field] || Configuration::NullDisplayField.new(field)) }.detect(&:any?)&.values
+      display_type || Array(default)
     end
 
     ##
@@ -127,8 +125,23 @@ def show_view_config
 
     private
 
+    # @return [Hash<String,Configuration::Field>]
+    def fields
+      @fields ||= Array(display_type).inject(display_fields) do |fields, display_type|
+        fields.merge(display_fields(configuration.for_display_type(display_type)))
+      end
+    end
+
+    def display_fields(config = configuration)
+      config[view_config.document_fields_key || :index_fields]
+    end
+
+    def field_config(field)
+      fields.fetch(field) { Configuration::NullDisplayField.new(field) }
+    end
+
     def field_presenter(field_config, options = {})
-      field_config.presenter.new(view_context, document, field_config, options.merge(field_presenter_options))
+      field_config.presenter.new(view_context, document, field_config, field_presenter_options.merge(options))
     end
 
     def field_presenter_options

app/presenters/blacklight/index_presenter.rb

@@ -5,16 +5,5 @@ class IndexPresenter < DocumentPresenter
     def view_config
       configuration.view_config(view_context.document_index_view_type)
     end
-
-    private
-
-    # @return [Hash<String,Configuration::Field>] all the fields for this index view
-    def fields
-      configuration.index_fields_for(display_type)
-    end
-
-    def field_config(field)
-      configuration.index_fields.fetch(field) { Configuration::NullDisplayField.new(field) }
-    end
   end
 end

app/presenters/blacklight/show_presenter.rb

@@ -4,15 +4,6 @@ module Blacklight
   class ShowPresenter < DocumentPresenter
     private
 
-    # @return [Hash<String,Configuration::Field>]
-    def fields
-      configuration.show_fields_for(display_type)
-    end
-
-    def field_config(field)
-      configuration.show_fields.fetch(field) { Configuration::NullDisplayField.new(field) }
-    end
-
     def field_presenter_options
       { context: 'show' }
     end

lib/blacklight/configuration.rb

@@ -120,6 +120,8 @@ def default_values
       title_field: nil,
       # solr field to use to render format-specific partials
       display_type_field: nil,
+      # the "field access" key to use to look up the document display fields
+      document_fields_key: :index_fields,
       # partials to render for each document(see #render_document_partials)
       partials: [],
       document_actions: NestedOpenStructWithHashAccess.new(ToolConfig),
@@ -144,6 +146,8 @@ def default_values
       document_presenter_class: nil,
       document_component: Blacklight::DocumentComponent,
       display_type_field: nil,
+      # the "field access" key to use to look up the document display fields
+      document_fields_key: :show_fields,
       # Default route parameters for 'show' requests.
       # Set this to a hash with additional arguments to merge into the route,
       # or set `controller: :current` to route to the current controller.
@@ -520,6 +524,7 @@ def for_display_type display_type, &_block
     ##
     # Return a list of fields for the index display that should be used for the
     # provided document.  This respects any configuration made using for_display_type
+    # @deprecated
     def index_fields_for(display_types)
       Array(display_types).inject(index_fields) do |fields, display_type|
         fields.merge(for_display_type(display_type).index_fields)
@@ -529,6 +534,7 @@ def index_fields_for(display_types)
     ##
     # Return a list of fields for the show page that should be used for the
     # provided document.  This respects any configuration made using for_display_type
+    # @deprecated
     def show_fields_for(display_types)
       Array(display_types).inject(show_fields) do |fields, display_type|
         fields.merge(for_display_type(display_type).show_fields)