Table of Contents


This gem provides all 6 GraphQL types: enums, inputs, interfaces, objects, scalars, and unions, and they all inherit from the same base Type class. This base class helps to maintain common information about its children’s classes.

Here is all the information you can get from them:

Base type

The base_type returns the top-most class of the type, ignoring the Type class.


The kind returns a symbol that indicates the kind of the type, which is one of the first 6 of this list in snake case.

Kind Enum

Same as above, but returning the string value instead.


  • The abstract? checks if the type is marked as abstract.
  • The hidden? checks if the type is marked as hidden.
  • The input_type? checks if the type can be used as an input;
  • The output_type? checks if the type can be used as an output;
  • The leaf_type? checks if the type is a leaf (enum or scalar);
  • The operational? checks if it is a fake type like _Query.


Unavailable This feature is yet to be published.

The hidden setting allow you to use types and directives that will never be exposed to a request. It enables you to use the GraphQL structure to meta-configure itself, like with authorization.

# app/graphql/enums/roles.rb
self.hidden = true

Beware even if a type is marked as hidden, it will still be published to the Type Map, which may cause unexpected overrides. To avoid that, use an isolated namespace.


Unavailable This feature is yet to be published.

Metadata is a simple Hash added to types that may contain any additional information you want to associate with them. See the example below for how to write and read values.

# Writing
metadata :counter, 1

# Reading


All types and fields have an equivalency operator =~. This operator helps to identify if the left side can be used as the right side. The equivalency takes into consideration several different factors, and each type has its own extension of this operator. For example:

  • An object is equivalent to an interface, if it implements that interface;
  • An object is equivalent to a union, if it is a member of that union;
  • The float scalar is equivalent to the time scalar because the latter inherits from the former.

Inline Creation

Schemas allow types to be created “inline”, meaning they won’t have a file of their own. When types are created this way, their constant is added to a NestedTypes module from where the creation started.

Types created inline can almost be fully configured using named arguments. But, you can always pass a block and add things as if inside their classes.

This requires further implementations and documentation as well.

Although this is not recommended, it can be handy in cases where you just need to simply define an union or an enum.

# app/graphql/app_schema.rb
union 'Person', of_types: %w[User Admin]

enum 'Role', values: %i[admin support]

Read mode about inline types.