Allow adding of custom predicates that take arrays (like IN/NOT IN)

lib/ransack/configuration.rb

@@ -19,6 +19,7 @@ module Ransack
       opts[:name] = name
       compounds = opts.delete(:compounds)
       compounds = true if compounds.nil?
+      compounds = false if opts[:wants_array]
       opts[:arel_predicate] = opts[:arel_predicate].to_s
 
       self.predicates[name] = Predicate.new(opts)

lib/ransack/predicate.rb

@@ -41,7 +41,7 @@ module Ransack
       @formatter = opts[:formatter]
       @validator = opts[:validator] || lambda { |v| v.respond_to?(:empty?) ? !v.empty? : !v.nil? }
       @compound = opts[:compound]
-      @wants_array = @compound || ['in', 'not_in'].include?(@arel_predicate)
+      @wants_array = opts[:wants_array] == true || @compound || ['in', 'not_in'].include?(@arel_predicate)
     end
 
     def eql?(other)

spec/ransack/configuration_spec.rb

@@ -45,5 +45,15 @@ module Ransack
       # restore original state so we don't break other tests
       Ransack.options = before
     end
+
+    it 'adds predicates that take arrays, overriding compounds' do
+      Ransack.configure do |config|
+        config.add_predicate :test_array_predicate, :wants_array => true, :compounds => true
+      end
+
+      Ransack.predicates['test_array_predicate'].wants_array.should eq true
+      Ransack.predicates.should_not have_key 'test_array_predicate_any'
+      Ransack.predicates.should_not have_key 'test_array_predicate_all'
+    end
   end
 end

spec/ransack/search_spec.rb

@@ -90,6 +90,20 @@ module Ransack
         conditions.should have(2).items
         conditions.map {|c| c.class}.should eq [Nodes::Condition, Nodes::Condition]
       end
+
+      it 'creates Conditions for custom predicates that take arrays' do
+        Ransack.configure do |config|
+          config.add_predicate 'ary_pred',
+          :wants_array => true
+        end
+
+        search = Search.new(Person, :name_ary_pred => ['Ernie', 'Bert'])
+        condition = search.base[:name_ary_pred]
+        condition.should be_a Nodes::Condition
+        condition.predicate.name.should eq 'ary_pred'
+        condition.attributes.first.name.should eq 'name'
+        condition.value.should eq ['Ernie', 'Bert']
+      end
     end
 
     describe '#result' do