Avoid overwriting association conditions with default scope

When joining ransackable associations in Rails 3, preserve both:

* association default_scope
* association conditions

Combining the stashed JoinAssociation with a separate string join for
the "AND" conditions looks like a hack, but there is no cleaner way to
extract the default_scope conditions with correct table aliases and
merge them back into the association since ActiveRecord rebuilds its own
join parts when generating the query.

lib/ransack/adapters/active_record/3.0/context.rb

@@ -182,23 +182,19 @@ def build_or_find_association(name, parent = @base, klass = nil)
               :build, Polyamorous::Join.new(name, @join_type, klass), parent
               )
             found_association = @join_dependency.join_associations.last
-            apply_default_conditions(found_association)
+
+            default_conditions = found_association.active_record.scoped.arel.constraints
+            if default_conditions.any?
+              and_default_conditions = "AND #{default_conditions.reduce(&:and).to_sql}"
+            end
+
             # Leverage the stashed association functionality in AR
-            @object = @object.joins(found_association)
+            @object = @object.joins(found_association).joins(and_default_conditions)
           end
 
           found_association
         end
 
-        def apply_default_conditions(join_association)
-          reflection = join_association.reflection
-          default_scope = join_association.active_record.scoped
-          default_conditions = default_scope.arel.where_clauses
-          if default_conditions.any?
-            reflection.options[:conditions] = default_conditions
-          end
-        end
-
       end
     end
   end

lib/ransack/adapters/active_record/3.1/context.rb

@@ -90,8 +90,8 @@ def join_associations
         #
         def join_sources
           base = Arel::SelectManager.new(@object.engine, @object.table)
-          joins = @object.joins_values
-          joins.each do |assoc|
+          @object.joins_values.each do |assoc|
+            next unless assoc.is_a?(JoinDependency::JoinAssociation)
             assoc.join_to(base)
           end
           base.join_sources
@@ -151,7 +151,7 @@ def build_join_dependency(relation)
               Constants::STRING_JOIN
             when Hash, Symbol, Array
               Constants::ASSOCIATION_JOIN
-            when ::ActiveRecord::Associations::JoinDependency::JoinAssociation
+            when JoinDependency::JoinAssociation
               Constants::STASHED_JOIN
             when Arel::Nodes::Join
               Constants::JOIN_NODE
@@ -196,23 +196,19 @@ def build_or_find_association(name, parent = @base, klass = nil)
               :build, Polyamorous::Join.new(name, @join_type, klass), parent
               )
             found_association = @join_dependency.join_associations.last
-            apply_default_conditions(found_association)
+
+            default_conditions = found_association.active_record.scoped.arel.constraints
+            if default_conditions.any?
+              and_default_conditions = "AND #{default_conditions.reduce(&:and).to_sql}"
+            end
+
             # Leverage the stashed association functionality in AR
-            @object = @object.joins(found_association)
+            @object = @object.joins(found_association).joins(and_default_conditions)
           end
 
           found_association
         end
 
-        def apply_default_conditions(join_association)
-          reflection = join_association.reflection
-          default_scope = join_association.active_record.scoped
-          default_conditions = default_scope.arel.where_clauses
-          if default_conditions.any?
-            reflection.options[:conditions] = default_conditions
-          end
-        end
-
       end
     end
   end

spec/ransack/search_spec.rb

@@ -93,9 +93,10 @@ module Ransack
         expect(condition.value).to eq 'Ernie'
       end
 
-      it 'preserves default scope conditions for associations' do
-        search = Search.new(Person, articles_title_eq: 'Test')
+      it 'preserves default scope and conditions for associations' do
+        search = Search.new(Person, published_articles_title_eq: 'Test')
         expect(search.result.to_sql).to include 'default_scope'
+        expect(search.result.to_sql).to include 'published'
       end
 
       it 'discards empty conditions' do

spec/support/schema.rb

@@ -33,6 +33,7 @@ class Person < ActiveRecord::Base
   belongs_to :parent, :class_name => 'Person', :foreign_key => :parent_id
   has_many   :children, :class_name => 'Person', :foreign_key => :parent_id
   has_many   :articles
+  has_many   :published_articles, :class_name => 'Article', :conditions => {published: true}
   has_many   :comments
   has_many   :authored_article_comments, :through => :articles,
              :source => :comments, :foreign_key => :person_id
@@ -171,6 +172,7 @@ def self.create
         t.string   :title
         t.text     :subject_header
         t.text     :body
+        t.boolean  :published, default: true
       end
 
       create_table :comments, :force => true do |t|