Class: ActiveRecord::Associations::JoinDependency
- Defined in:
- lib/brick.rb
Overview
For AR >= 4.2
Instance Method Summary collapse
-
#apply_column_aliases(relation) ⇒ Object
An intelligent .eager_load() and .includes() that creates t0_r0 style aliases only for the columns used in .select().
Instance Method Details
#apply_column_aliases(relation) ⇒ Object
An intelligent .eager_load() and .includes() that creates t0_r0 style aliases only for the columns used in .select(). To enable this behaviour, include the flag :_brick_eager_load as the first entry in your .select(). More information: discuss.rubyonrails.org/t/includes-and-select-for-joined-data/81640
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# File 'lib/brick.rb', line 1893 def apply_column_aliases(relation) if !(@join_root_alias = relation.select_values.empty?) && relation.select_values.first.to_s == '_brick_eager_load' relation.select_values.shift used_cols = {} # Find and expand out all column names being used in select(...) new_select_values = relation.select_values.map(&:to_s).each_with_object([]) do |col, s| if col.include?(' ') # Some expression? (No chance for a simple column reference) s << col # Just pass it through else col = if (col_parts = col.split('.')).length == 1 [col] else [col_parts[0..-2].join('.'), col_parts.last] end used_cols[col] = nil end end if new_select_values.present? relation.select_values = new_select_values else relation.select_values.clear end @aliases ||= Aliases.new(join_root.each_with_index.map do |join_part, i| join_alias = join_part.table&.table_alias || join_part.table_name keys = [join_part.base_klass.primary_key] # Always include the primary key # # %%% Optional to include all foreign keys: # keys.concat(join_part.base_klass.reflect_on_all_associations.select { |a| a.belongs_to? }.map(&:foreign_key)) # Add foreign keys out to referenced tables that we belongs_to join_part.children.each { |child| keys << child.reflection.foreign_key if child.reflection.belongs_to? } # Add the foreign key that got us here -- "the train we rode in on" -- if we arrived from # a has_many or has_one: if join_part.is_a?(ActiveRecord::Associations::JoinDependency::JoinAssociation) && !join_part.reflection.belongs_to? keys << join_part.reflection.foreign_key end keys = keys.compact # In case we're using composite_primary_keys j = 0 columns = join_part.column_names.each_with_object([]) do |column_name, s| # Include columns chosen in select(...) as well as the PK and any relevant FKs if used_cols.keys.find { |c| (c.length == 1 || c.first == join_alias) && c.last == column_name } || keys.find { |c| c == column_name } s << Aliases::Column.new(column_name, "t#{i}_r#{j}") end j += 1 end Aliases::Table.new(join_part, columns) end) end relation._select!(-> { aliases.columns }) end |