stop using with_exclusive_scope, ensuring other scopes stay in effect

README.markdown

@@ -62,4 +62,3 @@ Pitfalls
 
 * `validates_uniqueness_of` does not ignore items marked with a "deleted_at" flag
 * various eager-loading and associations-related issues (see ["Killing is_paranoid"](http://blog.semanticart.com/killing_is_paranoid/))
-* `find/count_with_destroyed` uses `with_exclusive_scope` and thus doesn't play nicely with named scopes

lib/is_paranoid.rb

@@ -15,35 +15,32 @@ module SafetyNet
     #  end
     def is_paranoid
       class_eval do
-        # This is the real magic.  All calls made to this model will append
-        # the conditions deleted_at => nil.  Exceptions require using
-        # exclusive_scope (see self.delete_all, self.count_with_destroyed,
-        # and self.find_with_destroyed )
+        # This is the real magic.  All calls made to this model will
+        # append the conditions deleted_at => nil.  Exceptions require
+        # using with_destroyed_scope (see self.delete_all,
+        # self.count_with_destroyed, and self.find_with_destroyed )
         default_scope :conditions => {:deleted_at => nil}
 
         # Actually delete the model, bypassing the safety net.  Because
         # this method is called internally by Model.delete(id) and on the
         # delete method in each instance, we don't need to specify those
         # methods separately
-        ## FIXME: this is dangerous. find a better solution
-        # def self.delete_all conditions = nil
-        #   self.with_exclusive_scope do
-        #     super conditions
-        #   end
-        # end
+        def self.delete_all conditions = nil
+          self.with_destroyed_scope { super conditions }
+        end
 
         # Return a count that includes the soft-deleted models.
         def self.count_with_destroyed *args
-          self.with_exclusive_scope { count(*args) }
+          self.with_destroyed_scope { count(*args) }
         end
 
         # Return instances of all models matching the query regardless
         # of whether or not they have been soft-deleted.
         def self.find_with_destroyed *args
-          self.with_exclusive_scope { find(*args) }
+          self.with_destroyed_scope { find(*args) }
         end
 
-        # Perofm a find only on destroyed instances
+        # Perform a find only on destroyed instances.
         def self.find_only_destroyed *args
           self.with_only_destroyed_scope { find(*args) }
         end
@@ -77,8 +74,37 @@ def destroy_without_callbacks
         end
 
         def self.with_only_destroyed_scope(&block)
-          with_exclusive_scope do
-            with_scope({:find => { :conditions => ["deleted_at IS NOT NULL"] }}, &block)
+          with_destroyed_scope do
+            table = connection.quote_table_name(table_name)
+            attr = connection.quote_column_name(:deleted_at)
+            with_scope(:find => { :conditions => "#{table}.#{attr} IS NOT NULL" }, &block)
+          end
+        end
+
+        def self.with_destroyed_scope
+          find = current_scoped_methods[:find]
+
+          if find[:conditions]
+            original = find[:conditions].dup
+
+            begin
+              case find[:conditions]
+              when Hash:
+                if find[:conditions][:deleted_at].nil?
+                  find[:conditions].delete(:deleted_at)
+                end
+              when String:
+                conditions = sanitize_conditions(:deleted_at => nil)
+                find[:conditions].gsub!(conditions, '1=1')
+              end
+
+              result = yield
+            ensure
+              find[:conditions] = original
+              return result if result
+            end
+          else
+            yield
           end
         end
       end

spec/is_paranoid_spec.rb

@@ -7,6 +7,9 @@ class Person < ActiveRecord::Base
 class Android < ActiveRecord::Base
   validates_uniqueness_of :name
   is_paranoid
+  named_scope :ordered, :order => 'name DESC'
+  named_scope :r2d2, :conditions => { :name => 'R2D2' }
+  named_scope :c3p0, :conditions => { :name => 'C3P0' }
 end
 
 describe Android do
@@ -88,4 +91,14 @@ class Android < ActiveRecord::Base
     @r2d2.destroy
     Android.find_only_destroyed(:all).should == [@r2d2]
   end
+
+  it "should honor named scopes" do
+    @r2d2.destroy
+    @c3p0.destroy
+    Android.r2d2.find_only_destroyed(:all).should == [@r2d2]
+    Android.c3p0.ordered.find_only_destroyed(:all).should == [@c3p0]
+    Android.ordered.find_only_destroyed(:all).should == [@r2d2,@c3p0]
+    Android.r2d2.c3p0.find_only_destroyed(:all).should == []
+    Android.find_only_destroyed(:all).should == [@r2d2,@c3p0]
+  end
 end