1 files changed, 45 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/relation/predicate_builder.rb b/activerecord/lib/active_record/relation/predicate_builder.rb
new file mode 100644
index 0000000000..6b7d941350
--- /dev/null
+++ b/activerecord/lib/active_record/relation/predicate_builder.rb
@@ -0,0 +1,45 @@
+module ActiveRecord
+  class PredicateBuilder
+
+    def initialize(engine)
+      @engine = engine
+    end
+
+    def build_from_hash(attributes, default_table)
+      predicates = attributes.map do |column, value|
+        table = default_table
+
+        if value.is_a?(Hash)
+          table = Arel::Table.new(column, :engine => @engine)
+          build_from_hash(value, table)
+        else
+          column = column.to_s
+
+          if column.include?('.')
+            table_name, column = column.split('.', 2)
+            table = Arel::Table.new(table_name, :engine => @engine)
+          end
+
+          attribute = table[column] || Arel::Attribute.new(table, column.to_sym)
+
+          case value
+          when Array, ActiveRecord::Associations::AssociationCollection, ActiveRecord::NamedScope::Scope
+            attribute.in(value)
+          when Range
+            # TODO : Arel should handle ranges with excluded end.
+            if value.exclude_end?
+              [attribute.gteq(value.begin), attribute.lt(value.end)]
+            else
+              attribute.in(value)
+            end
+          else
+            attribute.eq(value)
+          end
+        end
+      end
+
+      predicates.flatten
+    end
+
+  end
+end