Change PredicateBuilder handler methods to instance methods

This will allow us to pass the predicate builder into the constructor of
these handlers. The procs had to be changed to objects, because the
`PredicateBuilder` needs to be marshalable. If we ever decide to make
`register_handler` part of the public API, we should come up with a
better solution which allows procs.

/cc @mrgilman

[Sean Griffin & Melanie Gilman]

activerecord/lib/active_record/relation/predicate_builder.rb

@@ -1,13 +1,23 @@
 module ActiveRecord
   class PredicateBuilder # :nodoc:
-    @handlers = []
-
-    autoload :RelationHandler, 'active_record/relation/predicate_builder/relation_handler'
-    autoload :ArrayHandler, 'active_record/relation/predicate_builder/array_handler'
+    require 'active_record/relation/predicate_builder/array_handler'
+    require 'active_record/relation/predicate_builder/base_handler'
+    require 'active_record/relation/predicate_builder/basic_object_handler'
+    require 'active_record/relation/predicate_builder/class_handler'
+    require 'active_record/relation/predicate_builder/range_handler'
+    require 'active_record/relation/predicate_builder/relation_handler'
 
     def initialize(klass, table)
       @klass = klass
       @table = table
+      @handlers = []
+
+      register_handler(BasicObject, BasicObjectHandler.new)
+      register_handler(Class, ClassHandler.new)
+      register_handler(Base, BaseHandler.new)
+      register_handler(Range, RangeHandler.new)
+      register_handler(Relation, RelationHandler.new)
+      register_handler(Array, ArrayHandler.new)
     end
 
     def resolve_column_aliases(hash)
@@ -35,13 +45,13 @@ module ActiveRecord
       # PriceEstimate.where(estimate_of: treasure)
       if klass && reflection = klass._reflect_on_association(column)
         if reflection.polymorphic? && base_class = polymorphic_base_class_from_value(value)
-          queries << self.class.build(table[reflection.foreign_type], base_class.name)
+          queries << build(table[reflection.foreign_type], base_class.name)
         end
 
         column = reflection.foreign_key
       end
 
-      queries << self.class.build(table[column], value)
+      queries << build(table[column], value)
       queries
     end
 
@@ -79,33 +89,10 @@ module ActiveRecord
     #       )
     #     end
     #     ActiveRecord::PredicateBuilder.register_handler(MyCustomDateRange, handler)
-    def self.register_handler(klass, handler)
+    def register_handler(klass, handler)
       @handlers.unshift([klass, handler])
     end
 
-    register_handler(BasicObject, ->(attribute, value) { attribute.eq(value) })
-    register_handler(Class, ->(attribute, value) { deprecate_class_handler; attribute.eq(value.name) })
-    register_handler(Base, ->(attribute, value) { attribute.eq(value.id) })
-    register_handler(Range, ->(attribute, value) { attribute.between(value) })
-    register_handler(Relation, RelationHandler.new)
-    register_handler(Array, ArrayHandler.new)
-
-    def self.build(attribute, value)
-      handler_for(value).call(attribute, value)
-    end
-
-    def self.handler_for(object)
-      @handlers.detect { |klass, _| klass === object }.last
-    end
-    private_class_method :handler_for
-
-    def self.deprecate_class_handler
-      ActiveSupport::Deprecation.warn(<<-MSG.squish)
-        Passing a class as a value in an Active Record query is deprecated and
-        will be removed. Pass a string instead.
-      MSG
-    end
-
     protected
 
     attr_reader :klass, :table
@@ -141,5 +128,13 @@ module ActiveRecord
 
       attributes
     end
+
+    def build(attribute, value)
+      handler_for(value).call(attribute, value)
+    end
+
+    def handler_for(object)
+      @handlers.detect { |klass, _| klass === object }.last
+    end
   end
 end

activerecord/lib/active_record/relation/predicate_builder/base_handler.rb

@@ -0,0 +1,9 @@
+module ActiveRecord
+  class PredicateBuilder
+    class BaseHandler # :nodoc:
+      def call(attribute, value)
+        attribute.eq(value.id)
+      end
+    end
+  end
+end

activerecord/lib/active_record/relation/predicate_builder/basic_object_handler.rb

@@ -0,0 +1,9 @@
+module ActiveRecord
+  class PredicateBuilder
+    class BasicObjectHandler # :nodoc:
+      def call(attribute, value)
+        attribute.eq(value)
+      end
+    end
+  end
+end

activerecord/lib/active_record/relation/predicate_builder/class_handler.rb

@@ -0,0 +1,19 @@
+module ActiveRecord
+  class PredicateBuilder
+    class ClassHandler # :nodoc:
+      def call(attribute, value)
+        print_deprecation_warning
+        attribute.eq(value.name)
+      end
+
+      private
+
+      def print_deprecation_warning
+        ActiveSupport::Deprecation.warn(<<-MSG.squish)
+          Passing a class as a value in an Active Record query is deprecated and
+          will be removed. Pass a string instead.
+        MSG
+      end
+    end
+  end
+end

activerecord/lib/active_record/relation/predicate_builder/range_handler.rb

@@ -0,0 +1,9 @@
+module ActiveRecord
+  class PredicateBuilder
+    class RangeHandler # :nodoc:
+      def call(attribute, value)
+        attribute.between(value)
+      end
+    end
+  end
+end

activerecord/test/cases/relation/predicate_builder_test.rb

@@ -4,11 +4,13 @@ require 'models/topic'
 module ActiveRecord
   class PredicateBuilderTest < ActiveRecord::TestCase
     def test_registering_new_handlers
-      PredicateBuilder.register_handler(Regexp, proc do |column, value|
+      Topic.predicate_builder.register_handler(Regexp, proc do |column, value|
         Arel::Nodes::InfixOperation.new('~', column, Arel.sql(value.source))
       end)
 
       assert_match %r{["`]topics["`].["`]title["`] ~ rails}i, Topic.where(title: /rails/).to_sql
+    ensure
+      Topic.reset_column_information
     end
   end
 end