diff --git a/modules/openapi-generator/src/main/resources/ruby-client/partial_model_enum_class.mustache b/modules/openapi-generator/src/main/resources/ruby-client/partial_model_enum_class.mustache
index 4b8b5a0ffda..d2ddbff1977 100644
--- a/modules/openapi-generator/src/main/resources/ruby-client/partial_model_enum_class.mustache
+++ b/modules/openapi-generator/src/main/resources/ruby-client/partial_model_enum_class.mustache
@@ -2,6 +2,10 @@
     {{{name}}} = {{{value}}}.freeze{{/enumVars}}
 
 {{/allowableValues}}
+    def self.all_vars
+      @all_vars ||= [{{#allowableValues}}{{#enumVars}}{{{name}}}{{^-last}}, {{/-last}}{{/enumVars}}{{/allowableValues}}].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -13,8 +17,7 @@
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = {{classname}}.constants.select { |c| {{classname}}::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #{{{classname}}}" if constantValues.empty?
-      value
+      return value if {{classname}}.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #{{{classname}}}"
     end
   end
\ No newline at end of file
diff --git a/modules/openapi-generator/src/main/resources/ruby-client/partial_oneof_module_doc.mustache b/modules/openapi-generator/src/main/resources/ruby-client/partial_oneof_module_doc.mustache
index 64a6c32dc85..f86cefe92be 100644
--- a/modules/openapi-generator/src/main/resources/ruby-client/partial_oneof_module_doc.mustache
+++ b/modules/openapi-generator/src/main/resources/ruby-client/partial_oneof_module_doc.mustache
@@ -60,6 +60,7 @@ require '{{{gemName}}}'
 # }
 {{/-last}}
 {{/mappedModels}}
+```
 {{/discriminator}}
 
 ### build
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/enum_class.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/enum_class.rb
index cfb86babdbe..4b869b1b5dc 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/enum_class.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/enum_class.rb
@@ -19,6 +19,10 @@ module Petstore
     EFG = "-efg".freeze
     XYZ = "(xyz)".freeze
 
+    def self.all_vars
+      @all_vars ||= [ABC, EFG, XYZ].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = EnumClass.constants.select { |c| EnumClass::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #EnumClass" if constantValues.empty?
-      value
+      return value if EnumClass.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #EnumClass"
     end
   end
 end
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum.rb
index eebac71dd56..a2607e1d6c8 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum.rb
@@ -19,6 +19,10 @@ module Petstore
     APPROVED = "approved".freeze
     DELIVERED = "delivered".freeze
 
+    def self.all_vars
+      @all_vars ||= [PLACED, APPROVED, DELIVERED].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = OuterEnum.constants.select { |c| OuterEnum::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #OuterEnum" if constantValues.empty?
-      value
+      return value if OuterEnum.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #OuterEnum"
     end
   end
 end
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum_default_value.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum_default_value.rb
index 9962be8508e..25b93ca5840 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum_default_value.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum_default_value.rb
@@ -19,6 +19,10 @@ module Petstore
     APPROVED = "approved".freeze
     DELIVERED = "delivered".freeze
 
+    def self.all_vars
+      @all_vars ||= [PLACED, APPROVED, DELIVERED].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = OuterEnumDefaultValue.constants.select { |c| OuterEnumDefaultValue::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #OuterEnumDefaultValue" if constantValues.empty?
-      value
+      return value if OuterEnumDefaultValue.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #OuterEnumDefaultValue"
     end
   end
 end
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum_integer.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum_integer.rb
index e88e6690e13..0385366de48 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum_integer.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum_integer.rb
@@ -19,6 +19,10 @@ module Petstore
     N1 = 1.freeze
     N2 = 2.freeze
 
+    def self.all_vars
+      @all_vars ||= [N0, N1, N2].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = OuterEnumInteger.constants.select { |c| OuterEnumInteger::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #OuterEnumInteger" if constantValues.empty?
-      value
+      return value if OuterEnumInteger.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #OuterEnumInteger"
     end
   end
 end
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum_integer_default_value.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum_integer_default_value.rb
index 0f871b3f54e..e205433c9ff 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum_integer_default_value.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_enum_integer_default_value.rb
@@ -19,6 +19,10 @@ module Petstore
     N1 = 1.freeze
     N2 = 2.freeze
 
+    def self.all_vars
+      @all_vars ||= [N0, N1, N2].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = OuterEnumIntegerDefaultValue.constants.select { |c| OuterEnumIntegerDefaultValue::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #OuterEnumIntegerDefaultValue" if constantValues.empty?
-      value
+      return value if OuterEnumIntegerDefaultValue.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #OuterEnumIntegerDefaultValue"
     end
   end
 end
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/single_ref_type.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/single_ref_type.rb
index ef4d14083d1..8b0b29af57f 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/single_ref_type.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/single_ref_type.rb
@@ -18,6 +18,10 @@ module Petstore
     ADMIN = "admin".freeze
     USER = "user".freeze
 
+    def self.all_vars
+      @all_vars ||= [ADMIN, USER].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -29,9 +33,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = SingleRefType.constants.select { |c| SingleRefType::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #SingleRefType" if constantValues.empty?
-      value
+      return value if SingleRefType.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #SingleRefType"
     end
   end
 end
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/enum_class.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/enum_class.rb
index cfb86babdbe..4b869b1b5dc 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/enum_class.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/enum_class.rb
@@ -19,6 +19,10 @@ module Petstore
     EFG = "-efg".freeze
     XYZ = "(xyz)".freeze
 
+    def self.all_vars
+      @all_vars ||= [ABC, EFG, XYZ].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = EnumClass.constants.select { |c| EnumClass::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #EnumClass" if constantValues.empty?
-      value
+      return value if EnumClass.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #EnumClass"
     end
   end
 end
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum.rb
index eebac71dd56..a2607e1d6c8 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum.rb
@@ -19,6 +19,10 @@ module Petstore
     APPROVED = "approved".freeze
     DELIVERED = "delivered".freeze
 
+    def self.all_vars
+      @all_vars ||= [PLACED, APPROVED, DELIVERED].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = OuterEnum.constants.select { |c| OuterEnum::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #OuterEnum" if constantValues.empty?
-      value
+      return value if OuterEnum.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #OuterEnum"
     end
   end
 end
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum_default_value.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum_default_value.rb
index 9962be8508e..25b93ca5840 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum_default_value.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum_default_value.rb
@@ -19,6 +19,10 @@ module Petstore
     APPROVED = "approved".freeze
     DELIVERED = "delivered".freeze
 
+    def self.all_vars
+      @all_vars ||= [PLACED, APPROVED, DELIVERED].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = OuterEnumDefaultValue.constants.select { |c| OuterEnumDefaultValue::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #OuterEnumDefaultValue" if constantValues.empty?
-      value
+      return value if OuterEnumDefaultValue.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #OuterEnumDefaultValue"
     end
   end
 end
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum_integer.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum_integer.rb
index e88e6690e13..0385366de48 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum_integer.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum_integer.rb
@@ -19,6 +19,10 @@ module Petstore
     N1 = 1.freeze
     N2 = 2.freeze
 
+    def self.all_vars
+      @all_vars ||= [N0, N1, N2].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = OuterEnumInteger.constants.select { |c| OuterEnumInteger::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #OuterEnumInteger" if constantValues.empty?
-      value
+      return value if OuterEnumInteger.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #OuterEnumInteger"
     end
   end
 end
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum_integer_default_value.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum_integer_default_value.rb
index 0f871b3f54e..e205433c9ff 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum_integer_default_value.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_enum_integer_default_value.rb
@@ -19,6 +19,10 @@ module Petstore
     N1 = 1.freeze
     N2 = 2.freeze
 
+    def self.all_vars
+      @all_vars ||= [N0, N1, N2].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = OuterEnumIntegerDefaultValue.constants.select { |c| OuterEnumIntegerDefaultValue::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #OuterEnumIntegerDefaultValue" if constantValues.empty?
-      value
+      return value if OuterEnumIntegerDefaultValue.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #OuterEnumIntegerDefaultValue"
     end
   end
 end
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/single_ref_type.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/single_ref_type.rb
index ef4d14083d1..8b0b29af57f 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/single_ref_type.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/single_ref_type.rb
@@ -18,6 +18,10 @@ module Petstore
     ADMIN = "admin".freeze
     USER = "user".freeze
 
+    def self.all_vars
+      @all_vars ||= [ADMIN, USER].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -29,9 +33,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = SingleRefType.constants.select { |c| SingleRefType::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #SingleRefType" if constantValues.empty?
-      value
+      return value if SingleRefType.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #SingleRefType"
     end
   end
 end
diff --git a/samples/client/petstore/ruby/lib/petstore/models/enum_class.rb b/samples/client/petstore/ruby/lib/petstore/models/enum_class.rb
index cfb86babdbe..4b869b1b5dc 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/enum_class.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/enum_class.rb
@@ -19,6 +19,10 @@ module Petstore
     EFG = "-efg".freeze
     XYZ = "(xyz)".freeze
 
+    def self.all_vars
+      @all_vars ||= [ABC, EFG, XYZ].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = EnumClass.constants.select { |c| EnumClass::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #EnumClass" if constantValues.empty?
-      value
+      return value if EnumClass.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #EnumClass"
     end
   end
 end
diff --git a/samples/client/petstore/ruby/lib/petstore/models/outer_enum.rb b/samples/client/petstore/ruby/lib/petstore/models/outer_enum.rb
index eebac71dd56..a2607e1d6c8 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/outer_enum.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/outer_enum.rb
@@ -19,6 +19,10 @@ module Petstore
     APPROVED = "approved".freeze
     DELIVERED = "delivered".freeze
 
+    def self.all_vars
+      @all_vars ||= [PLACED, APPROVED, DELIVERED].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = OuterEnum.constants.select { |c| OuterEnum::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #OuterEnum" if constantValues.empty?
-      value
+      return value if OuterEnum.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #OuterEnum"
     end
   end
 end
diff --git a/samples/client/petstore/ruby/lib/petstore/models/outer_enum_default_value.rb b/samples/client/petstore/ruby/lib/petstore/models/outer_enum_default_value.rb
index 9962be8508e..25b93ca5840 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/outer_enum_default_value.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/outer_enum_default_value.rb
@@ -19,6 +19,10 @@ module Petstore
     APPROVED = "approved".freeze
     DELIVERED = "delivered".freeze
 
+    def self.all_vars
+      @all_vars ||= [PLACED, APPROVED, DELIVERED].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = OuterEnumDefaultValue.constants.select { |c| OuterEnumDefaultValue::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #OuterEnumDefaultValue" if constantValues.empty?
-      value
+      return value if OuterEnumDefaultValue.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #OuterEnumDefaultValue"
     end
   end
 end
diff --git a/samples/client/petstore/ruby/lib/petstore/models/outer_enum_integer.rb b/samples/client/petstore/ruby/lib/petstore/models/outer_enum_integer.rb
index e88e6690e13..0385366de48 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/outer_enum_integer.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/outer_enum_integer.rb
@@ -19,6 +19,10 @@ module Petstore
     N1 = 1.freeze
     N2 = 2.freeze
 
+    def self.all_vars
+      @all_vars ||= [N0, N1, N2].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = OuterEnumInteger.constants.select { |c| OuterEnumInteger::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #OuterEnumInteger" if constantValues.empty?
-      value
+      return value if OuterEnumInteger.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #OuterEnumInteger"
     end
   end
 end
diff --git a/samples/client/petstore/ruby/lib/petstore/models/outer_enum_integer_default_value.rb b/samples/client/petstore/ruby/lib/petstore/models/outer_enum_integer_default_value.rb
index 0f871b3f54e..e205433c9ff 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/outer_enum_integer_default_value.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/outer_enum_integer_default_value.rb
@@ -19,6 +19,10 @@ module Petstore
     N1 = 1.freeze
     N2 = 2.freeze
 
+    def self.all_vars
+      @all_vars ||= [N0, N1, N2].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -30,9 +34,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = OuterEnumIntegerDefaultValue.constants.select { |c| OuterEnumIntegerDefaultValue::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #OuterEnumIntegerDefaultValue" if constantValues.empty?
-      value
+      return value if OuterEnumIntegerDefaultValue.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #OuterEnumIntegerDefaultValue"
     end
   end
 end
diff --git a/samples/client/petstore/ruby/lib/petstore/models/single_ref_type.rb b/samples/client/petstore/ruby/lib/petstore/models/single_ref_type.rb
index ef4d14083d1..8b0b29af57f 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/single_ref_type.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/single_ref_type.rb
@@ -18,6 +18,10 @@ module Petstore
     ADMIN = "admin".freeze
     USER = "user".freeze
 
+    def self.all_vars
+      @all_vars ||= [ADMIN, USER].freeze
+    end
+
     # Builds the enum from string
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
@@ -29,9 +33,8 @@ module Petstore
     # @param [String] The enum value in the form of the string
     # @return [String] The enum value
     def build_from_hash(value)
-      constantValues = SingleRefType.constants.select { |c| SingleRefType::const_get(c) == value }
-      raise "Invalid ENUM value #{value} for class #SingleRefType" if constantValues.empty?
-      value
+      return value if SingleRefType.all_vars.include?(value)
+      raise "Invalid ENUM value #{value} for class #SingleRefType"
     end
   end
 end