Delay building arel relation as long as possible for improved introspection

activerecord/lib/active_record/associations.rb

@@ -2148,22 +2148,23 @@ module ActiveRecord
             end
 
             def relation
+              aliased = Arel::Table.new(table_name, :as => @aliased_table_name)
+
               if reflection.macro == :has_and_belongs_to_many
-                [Arel::Table.new(table_alias_for(options[:join_table], aliased_join_table_name)), Arel::Table.new(table_name_and_alias)]
+                [Arel::Table.new(options[:join_table], :as => aliased_join_table_name), aliased]
               elsif reflection.options[:through]
-                [Arel::Table.new(table_alias_for(through_reflection.klass.table_name, aliased_join_table_name)), Arel::Table.new(table_name_and_alias)]
+                [Arel::Table.new(through_reflection.klass.table_name, :as => aliased_join_table_name), aliased]
               else
-                Arel::Table.new(table_name_and_alias)
+                aliased
               end
             end
 
             def join_relation(joining_relation, join = nil)
               if (relations = relation).is_a?(Array)
-                joining_relation.
-                  joins(relations.first, Arel::OuterJoin).on(association_join.first).
-                  joins(relations.last, Arel::OuterJoin).on(association_join.last)
+                joining_relation.joins(Relation::JoinOperation.new(relations.first, Arel::OuterJoin, association_join.first)).
+                  joins(Relation::JoinOperation.new(relations.last, Arel::OuterJoin, association_join.last))
               else
-                joining_relation.joins(relations, Arel::OuterJoin).on(association_join)
+                joining_relation.joins(Relation::JoinOperation.new(relations, Arel::OuterJoin, association_join))
               end
             end
 

activerecord/lib/active_record/base.rb

@@ -1663,7 +1663,7 @@ module ActiveRecord #:nodoc:
 
         def build_association_joins(joins)
           join_dependency = ActiveRecord::Associations::ClassMethods::JoinDependency.new(self, joins, nil)
-          relation = active_relation.relation
+          relation = active_relation.table
           join_dependency.join_associations.map { |association|
             if (association_relation = association.relation).is_a?(Array)
               [Arel::InnerJoin.new(relation, association_relation.first, association.association_join.first).joins(relation),
@@ -2039,7 +2039,7 @@ module ActiveRecord #:nodoc:
         def sanitize_sql_hash_for_conditions(attrs, default_table_name = self.table_name)
           attrs = expand_hash_conditions_for_aggregates(attrs)
 
-          table = Arel::Table.new(default_table_name, active_relation_engine)
+          table = Arel::Table.new(self.table_name, :engine => active_relation_engine, :as => default_table_name)
           builder = PredicateBuilder.new(active_relation_engine)
           builder.build_from_hash(attrs, table).map(&:to_sql).join(' AND ')
         end

activerecord/lib/active_record/relation.rb

@@ -1,19 +1,19 @@
 module ActiveRecord
   class Relation
-    include QueryMethods, FinderMethods, CalculationMethods, SpawnMethods
+    JoinOperation = Struct.new(:relation, :join_class, :on)
+    ASSOCIATION_METHODS = [:includes, :eager_load, :preload]
+    MULTI_VALUE_METHODS = [:select, :group, :order, :joins, :where, :having]
+    SINGLE_VALUE_METHODS = [:limit, :offset, :lock, :readonly, :create_with, :from]
+
+    include FinderMethods, CalculationMethods, SpawnMethods, QueryMethods
 
     delegate :length, :collect, :map, :each, :all?, :to => :to_a
 
-    attr_reader :relation, :klass
-    attr_writer :readonly, :table
-    attr_accessor :preload_associations, :eager_load_associations, :includes_associations, :create_with_attributes
+    attr_reader :table, :klass
 
-    def initialize(klass, relation)
-      @klass, @relation = klass, relation
-      @preload_associations = []
-      @eager_load_associations = []
-      @includes_associations = []
-      @loaded, @readonly = false
+    def initialize(klass, table)
+      @klass, @table = klass, table
+      (ASSOCIATION_METHODS + MULTI_VALUE_METHODS).each {|v| instance_variable_set(:"@#{v}_values", [])}
     end
 
     def new(*args, &block)
@@ -29,7 +29,7 @@ module ActiveRecord
     end
 
     def respond_to?(method, include_private = false)
-      return true if @relation.respond_to?(method, include_private) || Array.method_defined?(method)
+      return true if arel.respond_to?(method, include_private) || Array.method_defined?(method)
 
       if match = DynamicFinderMatch.match(method)
         return true if @klass.send(:all_attributes_exists?, match.attribute_names)
@@ -43,33 +43,35 @@ module ActiveRecord
     def to_a
       return @records if loaded?
 
-      find_with_associations = @eager_load_associations.any? || references_eager_loaded_tables?
+      find_with_associations = @eager_load_values.any? || (@includes_values.any? && references_eager_loaded_tables?)
 
       @records = if find_with_associations
         begin
           @klass.send(:find_with_associations, {
-            :select => @relation.send(:select_clauses).join(', '),
-            :joins => @relation.joins(relation),
-            :group => @relation.send(:group_clauses).join(', '),
+            :select => arel.send(:select_clauses).join(', '),
+            :joins => arel.joins(arel),
+            :group => arel.send(:group_clauses).join(', '),
             :order => order_clause,
             :conditions => where_clause,
-            :limit => @relation.taken,
-            :offset => @relation.skipped,
-            :from => (@relation.send(:from_clauses) if @relation.send(:sources).present?)
+            :limit => arel.taken,
+            :offset => arel.skipped,
+            :from => (arel.send(:from_clauses) if arel.send(:sources).present?)
             },
-            ActiveRecord::Associations::ClassMethods::JoinDependency.new(@klass, @eager_load_associations + @includes_associations, nil))
+            ActiveRecord::Associations::ClassMethods::JoinDependency.new(@klass, @eager_load_values + @includes_values, nil))
         rescue ThrowResult
           []
         end
       else
-        @klass.find_by_sql(@relation.to_sql)
+        @klass.find_by_sql(arel.to_sql)
       end
 
-      preload = @preload_associations
-      preload +=  @includes_associations unless find_with_associations
+      preload = @preload_values
+      preload +=  @includes_values unless find_with_associations
       preload.each {|associations| @klass.send(:preload_associations, @records, associations) } 
 
-      @records.each { |record| record.readonly! } if @readonly
+      # @readonly_value is true only if set explicity. @implicit_readonly is true if there are JOINS and no explicit SELECT.
+      readonly = @readonly_value.nil? ? @implicit_readonly : @readonly_value
+      @records.each { |record| record.readonly! } if readonly
 
       @loaded = true
       @records
@@ -97,7 +99,7 @@ module ActiveRecord
       if block_given?
         to_a.many? { |*block_args| yield(*block_args) }
       else
-        @relation.send(:taken).present? ? to_a.many? : size > 1
+        arel.send(:taken).present? ? to_a.many? : size > 1
       end
     end
 
@@ -107,7 +109,7 @@ module ActiveRecord
     end
 
     def delete_all
-      @relation.delete.tap { reset }
+      arel.delete.tap { reset }
     end
 
     def delete(id_or_array)
@@ -124,28 +126,24 @@ module ActiveRecord
     end
 
     def reset
-      @first = @last = @to_sql = @order_clause = @scope_for_create = nil
+      @first = @last = @to_sql = @order_clause = @scope_for_create = @arel = nil
       @records = []
       self
     end
 
-    def table
-      @table ||= Arel::Table.new(@klass.table_name, :engine => @klass.active_relation_engine)
-    end
-
     def primary_key
       @primary_key ||= table[@klass.primary_key]
     end
 
     def to_sql
-      @to_sql ||= @relation.to_sql
+      @to_sql ||= arel.to_sql
     end
 
     protected
 
     def method_missing(method, *args, &block)
-      if @relation.respond_to?(method)
-        @relation.send(method, *args, &block)
+      if arel.respond_to?(method)
+        arel.send(method, *args, &block)
       elsif Array.method_defined?(method)
         to_a.send(method, *args, &block)
       elsif match = DynamicFinderMatch.match(method)
@@ -168,7 +166,7 @@ module ActiveRecord
 
     def scope_for_create
       @scope_for_create ||= begin
-        @create_with_attributes || wheres.inject({}) do |hash, where|
+        @create_with_value || wheres.inject({}) do |hash, where|
           hash[where.operand1.name] = where.operand2.value if where.is_a?(Arel::Predicates::Equality)
           hash
         end
@@ -176,15 +174,15 @@ module ActiveRecord
     end
 
     def where_clause(join_string = " AND ")
-      @relation.send(:where_clauses).join(join_string)
+      arel.send(:where_clauses).join(join_string)
     end
 
     def order_clause
-      @order_clause ||= @relation.send(:order_clauses).join(', ')
+      @order_clause ||= arel.send(:order_clauses).join(', ')
     end
 
     def references_eager_loaded_tables?
-      joined_tables = (tables_in_string(@relation.joins(relation)) + [table.name, table.table_alias]).compact.uniq
+      joined_tables = (tables_in_string(arel.joins(arel)) + [table.name, table.table_alias]).compact.uniq
       (tables_in_string(to_sql) - joined_tables).any?
     end
 

activerecord/lib/active_record/relation/calculation_methods.rb

@@ -25,7 +25,7 @@ module ActiveRecord
       operation = operation.to_s.downcase
 
       if operation == "count"
-        joins = @relation.joins(relation)
+        joins = arel.joins(arel)
         if joins.present? && joins =~ /LEFT OUTER/i
           distinct = true
           column_name = @klass.primary_key if column_name == :all
@@ -40,7 +40,7 @@ module ActiveRecord
       distinct = options[:distinct] || distinct
       column_name = :all if column_name.blank? && operation == "count"
 
-      if @relation.send(:groupings).any?
+      if arel.send(:groupings).any?
         return execute_grouped_calculation(operation, column_name)
       else
         return execute_simple_calculation(operation, column_name, distinct)
@@ -63,7 +63,7 @@ module ActiveRecord
     end
 
     def execute_grouped_calculation(operation, column_name) #:nodoc:
-      group_attr      = @relation.send(:groupings).first.value
+      group_attr      = arel.send(:groupings).first.value
       association     = @klass.reflect_on_association(group_attr.to_sym)
       associated      = association && association.macro == :belongs_to # only count belongs_to associations
       group_field     = associated ? association.primary_key_name : group_attr
@@ -165,12 +165,8 @@ module ActiveRecord
       column ? column.type_cast(value) : value
     end
 
-    def get_projection_name_from_chained_relations(relation = @relation)
-      if relation.respond_to?(:projections) && relation.projections.present?
-        relation.send(:select_clauses).join(', ')
-      elsif relation.respond_to?(:relation)
-        get_projection_name_from_chained_relations(relation.relation)
-      end
+    def get_projection_name_from_chained_relations
+      @select_values.join(", ") if @select_values.present?
     end
 
   end

activerecord/lib/active_record/relation/finder_methods.rb

@@ -93,15 +93,15 @@ module ActiveRecord
       result = where(primary_key.in(ids)).all
 
       expected_size =
-        if @relation.taken && ids.size > @relation.taken
-          @relation.taken
+        if arel.taken && ids.size > arel.taken
+          arel.taken
         else
           ids.size
         end
 
       # 11 ids with limit 3, offset 9 should give 2 results.
-      if @relation.skipped && (ids.size - @relation.skipped < expected_size)
-        expected_size = ids.size - @relation.skipped
+      if arel.skipped && (ids.size - arel.skipped < expected_size)
+        expected_size = ids.size - arel.skipped
       end
 
       if result.size == expected_size

activerecord/lib/active_record/relation/query_methods.rb

@@ -1,68 +1,42 @@
 module ActiveRecord
   module QueryMethods
+    extend ActiveSupport::Concern
 
-    def preload(*associations)
-      spawn.tap {|r| r.preload_associations += Array.wrap(associations) }
-    end
+    included do
+      (ActiveRecord::Relation::ASSOCIATION_METHODS + ActiveRecord::Relation::MULTI_VALUE_METHODS).each do |query_method|
+        attr_accessor :"#{query_method}_values"
 
-    def includes(*associations)
-      spawn.tap {|r| r.includes_associations += Array.wrap(associations) }
-    end
-
-    def eager_load(*associations)
-      spawn.tap {|r| r.eager_load_associations += Array.wrap(associations) }
-    end
-
-    def readonly(status = true)
-      spawn.tap {|r| r.readonly = status }
-    end
-
-    def create_with(attributes = {})
-      spawn.tap {|r| r.create_with_attributes = attributes }
-    end
-
-    def select(selects)
-      if selects.present?
-        relation = spawn(@relation.project(selects))
-        relation.readonly = @relation.joins(relation).present? ? false : @readonly
-        relation
-      else
-        spawn
-      end
-    end
-
-    def from(from)
-      from.present? ? spawn(@relation.from(from)) : spawn
-    end
-
-    def having(*args)
-      return spawn if args.blank?
-
-      if [String, Hash, Array].include?(args.first.class)
-        havings = @klass.send(:merge_conditions, args.size > 1 ? Array.wrap(args) : args.first)
-      else
-        havings = args.first
+        class_eval <<-CEVAL
+          def #{query_method}(*args)
+            spawn.tap do |new_relation|
+              new_relation.#{query_method}_values ||= []
+              value = args.size > 1 ? [args] : Array.wrap(args)
+              new_relation.#{query_method}_values += value
+            end
+          end
+        CEVAL
       end
 
-      spawn(@relation.having(havings))
-    end
+      ActiveRecord::Relation::SINGLE_VALUE_METHODS.each do |query_method|
+        attr_accessor :"#{query_method}_value"
 
-    def group(groups)
-      groups.present? ? spawn(@relation.group(groups)) : spawn
-    end
-
-    def order(orders)
-      orders.present? ? spawn(@relation.order(orders)) : spawn
+        class_eval <<-CEVAL
+          def #{query_method}(value = true)
+            spawn.tap do |new_relation|
+              new_relation.#{query_method}_value = value
+            end
+          end
+        CEVAL
+      end
     end
 
     def lock(locks = true)
+      relation = spawn
       case locks
-      when String
-        spawn(@relation.lock(locks))
-      when TrueClass, NilClass
-        spawn(@relation.lock)
+      when String, TrueClass, NilClass
+        spawn.tap {|new_relation| new_relation.lock_value = locks || true }
       else
-        spawn
+        spawn.tap {|new_relation| new_relation.lock_value = false }
       end
     end
 
@@ -70,7 +44,7 @@ module ActiveRecord
       relation = spawn
       relation.instance_variable_set(:@orders, nil)
 
-      order_clause = @relation.send(:order_clauses).join(', ')
+      order_clause = arel.send(:order_clauses).join(', ')
       if order_clause.present?
         relation.order(reverse_sql_order(order_clause))
       else
@@ -78,39 +52,74 @@ module ActiveRecord
       end
     end
 
-    def limit(limits)
-      limits.present? ? spawn(@relation.take(limits)) : spawn
+    def arel
+      @arel ||= build_arel
     end
 
-    def offset(offsets)
-      offsets.present? ? spawn(@relation.skip(offsets)) : spawn
-    end
+    def build_arel
+      arel = table
 
-    def on(join)
-      spawn(@relation.on(join))
-    end
+      @joins_values.each do |j|
+        next if j.blank?
 
-    def joins(join, join_type = nil)
-      return spawn if join.blank?
+        @implicit_readonly = true
 
-      join_relation = case join
-      when String
-        @relation.join(join)
-      when Hash, Array, Symbol
-        if @klass.send(:array_of_strings?, join)
-          @relation.join(join.join(' '))
+        case j
+        when Relation::JoinOperation
+          arel = arel.join(j.relation, j.join_class).on(j.on)
+        when Hash, Array, Symbol
+          if @klass.send(:array_of_strings?, j)
+            arel = arel.join(j.join(' '))
+          else
+            arel = arel.join(@klass.send(:build_association_joins, j))
+          end
         else
-          @relation.join(@klass.send(:build_association_joins, join))
+          arel = arel.join(j)
         end
-      else
-        @relation.join(join, join_type)
       end
 
-      spawn(join_relation).tap { |r| r.readonly = true }
+      @where_values.each do |where|
+        if conditions = build_where(where)
+          arel = conditions.is_a?(String) ? arel.where(conditions) : arel.where(*conditions)
+        end
+      end
+
+      @having_values.each do |where|
+        if conditions = build_where(where)
+          arel = conditions.is_a?(String) ? arel.having(conditions) : arel.having(*conditions)
+        end
+      end
+
+      arel = arel.take(@limit_value) if @limit_value.present?
+      arel = arel.skip(@offset_value) if @offset_value.present?
+
+      @group_values.each do |g|
+        arel = arel.group(g) if g.present?
+      end
+
+      @order_values.each do |o|
+        arel = arel.order(o) if o.present?
+      end
+
+      @select_values.each do |s|
+        @implicit_readonly = false
+        arel = arel.project(s) if s.present?
+      end
+
+      arel = arel.from(@from_value) if @from_value.present?
+
+      case @lock_value
+      when TrueClass
+        arel = arel.lock
+      when String
+        arel = arel.lock(@lock_value)
+      end
+
+      arel
     end
 
-    def where(*args)
-      return spawn if args.blank?
+    def build_where(*args)
+      return if args.blank?
 
       builder = PredicateBuilder.new(Arel::Sql::Engine.new(@klass))
 
@@ -124,7 +133,7 @@ module ActiveRecord
         args.first
       end
 
-      conditions.is_a?(String) ? spawn(@relation.where(conditions)) : spawn(@relation.where(*conditions))
+      conditions
     end
 
     private

activerecord/lib/active_record/relation/spawn_methods.rb

@@ -1,49 +1,51 @@
 module ActiveRecord
   module SpawnMethods
-    def spawn(relation = @relation)
-      relation = Relation.new(@klass, relation)
-      relation.readonly = @readonly
-      relation.preload_associations = @preload_associations
-      relation.eager_load_associations = @eager_load_associations
-      relation.includes_associations = @includes_associations
-      relation.create_with_attributes = @create_with_attributes
-      relation.table = table
+    def spawn(arel_table = self.table)
+      relation = Relation.new(@klass, arel_table)
+
+      (Relation::ASSOCIATION_METHODS + Relation::MULTI_VALUE_METHODS).each do |query_method|
+        relation.send(:"#{query_method}_values=", send(:"#{query_method}_values"))
+      end
+
+      Relation::SINGLE_VALUE_METHODS.each do |query_method|
+        relation.send(:"#{query_method}_value=", send(:"#{query_method}_value"))
+      end
+
       relation
     end
 
     def merge(r)
       raise ArgumentError, "Cannot merge a #{r.klass.name} relation with #{@klass.name} relation" if r.klass != @klass
 
-      merged_relation = spawn(table).eager_load(r.eager_load_associations).preload(r.preload_associations).includes(r.includes_associations)
-      merged_relation.readonly = r.readonly
+      merged_relation = spawn.eager_load(r.eager_load_values).preload(r.preload_values).includes(r.includes_values)
 
-      [self.relation, r.relation].each do |arel|
-        merged_relation = merged_relation.
-          joins(arel.joins(arel)).
-          group(arel.groupings).
-          limit(arel.taken).
-          offset(arel.skipped).
-          select(arel.send(:select_clauses)).
-          from(arel.sources).
-          having(arel.havings).
-          lock(arel.locked)
-      end
+      merged_relation.readonly_value = r.readonly_value unless merged_relation.readonly_value
+      merged_relation.limit_value = r.limit_value unless merged_relation.limit_value
+      merged_relation.lock_value = r.lock_value unless merged_relation.lock_value
 
-      relation_order = r.send(:order_clause)
-      merged_order = relation_order.present? ? relation_order : order_clause
-      merged_relation = merged_relation.order(merged_order)
+      merged_relation = merged_relation.
+        joins(r.joins_values).
+        group(r.group_values).
+        offset(r.offset_value).
+        select(r.select_values).
+        from(r.from_value).
+        having(r.having_values)
 
-      merged_relation.create_with_attributes = @create_with_attributes
+      relation_order = r.order_values
+      merged_order = relation_order.present? ? relation_order : order_values
+      merged_relation.order_values = merged_order
 
-      if @create_with_attributes && r.create_with_attributes
-        merged_relation.create_with_attributes = @create_with_attributes.merge(r.create_with_attributes)
+      merged_relation.create_with_value = @create_with_value
+
+      if @create_with_value && r.create_with_value
+        merged_relation.create_with_value = @create_with_value.merge(r.create_with_value)
       else
-        merged_relation.create_with_attributes = r.create_with_attributes || @create_with_attributes
+        merged_relation.create_with_value = r.create_with_value || @create_with_value
       end
 
-      merged_wheres = @relation.wheres
+      merged_wheres = @where_values
 
-      r.wheres.each do |w|
+      r.where_values.each do |w|
         if w.is_a?(Arel::Predicates::Equality)
           merged_wheres = merged_wheres.reject {|p| p.is_a?(Arel::Predicates::Equality) && p.operand1.name == w.operand1.name }
         end
@@ -51,32 +53,23 @@ module ActiveRecord
         merged_wheres << w
       end
 
-      merged_relation.where(*merged_wheres)
+      merged_relation.where_values = merged_wheres
+
+      merged_relation
     end
 
     alias :& :merge
 
     def except(*skips)
       result = Relation.new(@klass, table)
-      result.table = table
 
-      [:eager_load, :preload, :includes].each do |load_method|
-        result = result.send(load_method, send(:"#{load_method}_associations"))
+      (Relation::ASSOCIATION_METHODS + Relation::MULTI_VALUE_METHODS).each do |method|
+        result.send(:"#{method}_values=", send(:"#{method}_values")) unless skips.include?(method)
       end
 
-      result.readonly = self.readonly unless skips.include?(:readonly)
-      result.create_with_attributes = @create_with_attributes unless skips.include?(:create_with)
-
-      result = result.joins(@relation.joins(@relation)) unless skips.include?(:joins)
-      result = result.group(@relation.groupings) unless skips.include?(:group)
-      result = result.limit(@relation.taken) unless skips.include?(:limit)
-      result = result.offset(@relation.skipped) unless skips.include?(:offset)
-      result = result.select(@relation.send(:select_clauses)) unless skips.include?(:select)
-      result = result.from(@relation.sources) unless skips.include?(:from)
-      result = result.order(order_clause) unless skips.include?(:order)
-      result = result.where(*@relation.wheres) unless skips.include?(:where)
-      result = result.having(*@relation.havings) unless skips.include?(:having)
-      result = result.lock(@relation.locked) unless skips.include?(:lock)
+      Relation::SINGLE_VALUE_METHODS.each do |method|
+        result.send(:"#{method}_value=", send(:"#{method}_value")) unless skips.include?(method)
+      end
 
       result
     end