1 files changed, 17 insertions, 76 deletions

diff --git a/activerecord/lib/active_record/relation/spawn_methods.rb b/activerecord/lib/active_record/relation/spawn_methods.rb
index 19ec41e5ca..a365b5723b 100644
--- a/activerecord/lib/active_record/relation/spawn_methods.rb
+++ b/activerecord/lib/active_record/relation/spawn_methods.rb
@@ -1,81 +1,24 @@
 require 'active_support/core_ext/object/blank'
+require 'active_record/relation/merger'
 
 module ActiveRecord
   module SpawnMethods
-    def merge(r)
-      return self unless r
-      return to_a & r if r.is_a?(Array)
-
-      merged_relation = clone
-
-      r = r.with_default_scope if r.default_scoped? && r.klass != klass
-
-      Relation::ASSOCIATION_METHODS.each do |method|
-        value = r.send(:"#{method}_values")
-
-        unless value.empty?
-          if method == :includes
-            merged_relation = merged_relation.includes(value)
-          else
-            merged_relation.send(:"#{method}_values=", value)
-          end
-        end
-      end
-
-      (Relation::MULTI_VALUE_METHODS - [:joins, :where, :order, :binds]).each do |method|
-        value = r.send(:"#{method}_values")
-        next if value.empty?
-
-        value += merged_relation.send(:"#{method}_values")
-        merged_relation.send :"#{method}_values=", value
-      end
-
-      merged_relation.joins_values += r.joins_values
-
-      merged_wheres = @where_values + r.where_values
-
-      merged_binds = (@bind_values + r.bind_values).uniq(&:first)
-
-      unless @where_values.empty?
-        # Remove duplicates, last one wins.
-        seen = Hash.new { |h,table| h[table] = {} }
-        merged_wheres = merged_wheres.reverse.reject { |w|
-          nuke = false
-          if w.respond_to?(:operator) && w.operator == :==
-            name              = w.left.name
-            table             = w.left.relation.name
-            nuke              = seen[table][name]
-            seen[table][name] = true
-          end
-          nuke
-        }.reverse
-      end
-
-      merged_relation.where_values = merged_wheres
-      merged_relation.bind_values = merged_binds
-
-      (Relation::SINGLE_VALUE_METHODS - [:lock, :create_with, :reordering]).each do |method|
-        value = r.send(:"#{method}_value")
-        merged_relation.send(:"#{method}_value=", value) unless value.nil?
+    def merge(other)
+      if other.is_a?(Array)
+        to_a & other
+      elsif other
+        clone.merge!(other)
+      else
+        self
       end
+    end
 
-      merged_relation.lock_value = r.lock_value unless merged_relation.lock_value
-
-      merged_relation = merged_relation.create_with(r.create_with_value) unless r.create_with_value.empty?
-
-      if (r.reordering_value)
-        # override any order specified in the original relation
-        merged_relation.reordering_value = true
-        merged_relation.order_values = r.order_values
+    def merge!(other)
+      if other.is_a?(Hash)
+        Relation::HashMerger.new(self, other).merge
       else
-        # merge in order_values from r
-        merged_relation.order_values += r.order_values
+        Relation::Merger.new(self, other).merge
       end
-
-      # Apply scope extension modules
-      merged_relation.send :apply_modules, r.extensions
-
-      merged_relation
     end
 
     # Removes from the query the condition(s) specified in +skips+.
@@ -89,7 +32,7 @@ module ActiveRecord
       result = self.class.new(@klass, table)
       result.default_scoped = default_scoped
 
-      ((Relation::ASSOCIATION_METHODS + Relation::MULTI_VALUE_METHODS) - skips).each do |method|
+      (Relation::MULTI_VALUE_METHODS - skips).each do |method|
         result.send(:"#{method}_values=", send(:"#{method}_values"))
       end
 
@@ -97,8 +40,7 @@ module ActiveRecord
         result.send(:"#{method}_value=", send(:"#{method}_value"))
       end
 
-      # Apply scope extension modules
-      result.send(:apply_modules, extensions)
+      result.extend(*extending_values) if extending_values.any?
 
       result
     end
@@ -114,7 +56,7 @@ module ActiveRecord
       result = self.class.new(@klass, table)
       result.default_scoped = default_scoped
 
-      ((Relation::ASSOCIATION_METHODS + Relation::MULTI_VALUE_METHODS) & onlies).each do |method|
+      (Relation::MULTI_VALUE_METHODS & onlies).each do |method|
         result.send(:"#{method}_values=", send(:"#{method}_values"))
       end
 
@@ -122,8 +64,7 @@ module ActiveRecord
         result.send(:"#{method}_value=", send(:"#{method}_value"))
       end
 
-      # Apply scope extension modules
-      result.send(:apply_modules, extensions)
+      result.extend(*extending_values) if extending_values.any?
 
       result
     end