Extract clusterfuck method for surgery

2 files changed, 92 insertions, 71 deletions

diff --git a/activerecord/lib/active_record/relation/merger.rb b/activerecord/lib/active_record/relation/merger.rb
new file mode 100644
index 0000000000..2f50b9a492
--- /dev/null
+++ b/activerecord/lib/active_record/relation/merger.rb
@@ -0,0 +1,84 @@
+module ActiveRecord
+  class Relation
+    class Merger
+      attr_reader :relation, :other
+
+      def initialize(relation, other)
+        @relation = relation
+
+        if other.default_scoped? && other.klass != relation.klass
+          @other = other.with_default_scope
+        else
+          @other = other
+        end
+      end
+
+      def merge
+        Relation::ASSOCIATION_METHODS.each do |method|
+          value = other.send(:"#{method}_values")
+
+          unless value.empty?
+            relation.send("#{method}!", value)
+          end
+        end
+
+        (Relation::MULTI_VALUE_METHODS - [:joins, :where, :order, :binds]).each do |method|
+          value = other.send(:"#{method}_values")
+          next if value.empty?
+
+          value += relation.send(:"#{method}_values")
+          relation.send :"#{method}_values=", value
+        end
+
+        relation.joins_values += other.joins_values
+
+        merged_wheres = relation.where_values + other.where_values
+
+        merged_binds = (relation.bind_values + other.bind_values).uniq(&:first)
+
+        unless relation.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
+
+        relation.where_values = merged_wheres
+        relation.bind_values = merged_binds
+
+        (Relation::SINGLE_VALUE_METHODS - [:lock, :create_with, :reordering]).each do |method|
+          value = other.send(:"#{method}_value")
+          relation.send(:"#{method}_value=", value) unless value.nil?
+        end
+
+        relation.lock_value = other.lock_value unless relation.lock_value
+
+        unless other.create_with_value.empty?
+          relation.create_with_value = (relation.create_with_value || {}).merge(other.create_with_value)
+        end
+
+        if other.reordering_value
+          # override any order specified in the original relation
+          relation.reordering_value = true
+          relation.order_values = other.order_values
+        else
+          # merge in order_values from r
+          relation.order_values += other.order_values
+        end
+
+        # Apply scope extension modules
+        relation.send :apply_modules, other.extensions
+
+        relation
+      end
+    end
+  end
+end
diff --git a/activerecord/lib/active_record/relation/spawn_methods.rb b/activerecord/lib/active_record/relation/spawn_methods.rb
index 19ec41e5ca..cdea847fb8 100644
--- a/activerecord/lib/active_record/relation/spawn_methods.rb
+++ b/activerecord/lib/active_record/relation/spawn_methods.rb
@@ -1,81 +1,18 @@
 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
+    def merge(other)
+      if other
+        if other.is_a?(Array)
+          to_a & other
+        else
+          ActiveRecord::Relation::Merger.new(clone, other).merge
         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?
-      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
       else
-        # merge in order_values from r
-        merged_relation.order_values += r.order_values
+        self
       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+.