Add subform_includes to column, and preload_for_form controller method

So associations can be preloaded on edit action, speed up on big forms with long subforms or many nested subforms

Author: scambra

CHANGELOG.rdoc

@@ -1,6 +1,7 @@
 - Integrate LogicalQueryParser, supporting full logical search, or simplified searches with 'all keywords' and 'any keyword' operators
 - Display unauthorized column in form as show action, so show_ui or show override is used if exists
 - Display unauthorized subform with show_ui as show action, to display readonly subform tables
+- Add subform_includes to column, and preload_for_form method to preload associations on edit action, speed up on big forms with long subforms or many nested subforms
 
 = 4.1.1 (not released yet)
 - Load dartsass-sprockets, so it isn't required in the Gemfile

lib/active_scaffold/actions/core.rb

@@ -148,10 +148,8 @@ def parent_controller_name
 
     def setup_parent
       cfg = main_form_controller.active_scaffold_config
-      parent_model = cfg.model
-      parent = parent_model.new
-      copy_attributes(find_if_allowed(params[:parent_id], :read, parent_model), parent) if params[:parent_id]
-      parent.id = params[:parent_id]
+      parent = cfg.model.new
+      copy_data_from_saved_record(params[:parent_id], cfg, parent) if params[:parent_id]
       apply_constraints_to_record(parent) unless params[:parent_id]
       if @column.send_form_on_update_column
         parent = update_record_from_params(parent, cfg.send(params[:parent_id] ? :update : :create).columns, params[:record], true)
@@ -166,6 +164,12 @@ def setup_parent
       parent
     end
 
+    def copy_data_from_saved_record(id, config = active_scaffold_config, record = nil)
+      preload_values = preload_for_form(config.update.columns) if config.actions.include?(:update)
+      saved_record = find_if_allowed(id, :read, config.model.preload(preload_values))
+      copy_attributes(saved_record, record).tap { |new_record| new_record.id = id }
+    end
+
     def find_from_scope(parent, scope)
       parts = scope[1..-2].split('][')
       record = parent
@@ -190,6 +194,9 @@ def find_from_scope(parent, scope)
     def copy_attributes(orig, dst = nil)
       dst ||= orig.class.new
       orig.attributes.each { |attr, value| dst.send :write_attribute, attr, value }
+      orig.class.reflect_on_all_associations.each do |assoc|
+        dst.association(assoc.name).target = orig.association(assoc.name).target if orig.send(:association_cached?, assoc.name)
+      end
       dst
     end
 
@@ -203,6 +210,27 @@ def parent_sti_controller
       @parent_sti_controller
     end
 
+    def preload_for_form(columns, preloaded_models = [])
+      association_columns = []
+      columns.each_column(flatten: true, skip_authorization: true) do |column|
+        association_columns << column if column.association && column.subform_includes
+      end
+
+      association_columns.filter_map do |column|
+        if column.form_ui.nil? && column.subform_includes == true && preloaded_models.exclude?(column.association.klass)
+          config = active_scaffold_config_for(column.association.klass)
+          if config.actions.include?(:subform)
+            preload_values = preload_for_form(config.subform.columns, preloaded_models + [column.association.klass])
+          end
+          preload_values ? {column.name => preload_values} : column.name
+        elsif column.subform_includes != true
+          {column.name => column.subform_includes}
+        else
+          column.name
+        end
+      end
+    end
+
     # override this method if you want to do something after render_field
     def after_render_field(record, column); end
 

lib/active_scaffold/actions/update.rb

@@ -97,7 +97,8 @@ def update_columns_names
     # A simple method to find and prepare a record for editing
     # May be overridden to customize the record (set default values, etc.)
     def do_edit
-      @record = find_if_allowed(params[:id], :update)
+      preload_values = preload_for_form(active_scaffold_config.update.columns)
+      @record = find_if_allowed(params[:id], :update, filtered_query.preload(preload_values))
     end
 
     # A complex method to update a record. The complexity comes from the support for subforms,

lib/active_scaffold/data_structures/action_columns.rb

@@ -86,7 +86,7 @@ def each_column(options = {}, &proc)
             yield item
           end
         else
-          next if skip_column?(item, options)
+          next if !options[:skip_authorization] && skip_column?(item, options)
 
           yield columns[item] || ActiveScaffold::DataStructures::Column.new(item.to_sym, columns.active_record_class)
         end

lib/active_scaffold/data_structures/column.rb

@@ -92,6 +92,11 @@ module ProxyableMethods
         # a collection of associations to pre-load when finding the records on a page
         attr_reader :includes
 
+        # a collection of associations to pre-load when the column is used as a subform,
+        # defaults to true, which means get associations from subform columns in the associated controller
+        # set to any other value to avoid checking the associated controller, false or nil to prevent preloading
+        attr_reader :subform_includes
+
         # a place to store dev's column specific options
         attr_writer :options
 
@@ -286,6 +291,14 @@ def includes=(value)
           end
       end
 
+      def subform_includes=(value)
+        @subform_includes =
+          case value
+          when Array, TrueClass then value
+          else value ? [value] : value # not convert nil to [nil]
+          end
+      end
+
       # a collection of associations to do left join when this column is included on search
       def search_joins
         @search_joins || includes
@@ -515,12 +528,13 @@ def initialize(name, active_record_class, delegated_association = nil) # :nodoc:
       if delegated_association
         self.includes = includes ? [delegated_association.name => includes] : [delegated_association.name]
       end
+      self.subform_includes = true if association
 
       # default all the configurable variables
       self.css_class = ''
       validators_force_require_on = active_record_class.validators_on(name)
-                                      .map { |val| validator_force_required?(val) }
-                                      .compact_blank
+                                                       .map { |val| validator_force_required?(val) }
+                                                       .compact_blank
       self.required = validators_force_require_on.any?(true) ||
                       validators_force_require_on.reject { |opt| opt == true }.flatten.presence
       self.sort = true