feat: add TypeSystem directives support with introspection

This adds full TypeSystem directive support as requested in issue absinthe-graphql#1003:

- Add `applied_directives` field to all Type structs (Object, Scalar,
  Field, Interface, Union, Enum, InputObject, Argument, Enum.Value)
- Preserve applied directives through the build phase from Blueprint
  to final Type structs
- Add `__AppliedDirective` and `__DirectiveArgument` introspection types
- Add `appliedDirectives` field to `__Type`, `__Field`, `__InputValue`,
  and `__EnumValue` introspection types
- TypeSystem directives can be applied to all spec-defined locations:
  SCHEMA, SCALAR, OBJECT, FIELD_DEFINITION, ARGUMENT_DEFINITION,
  INTERFACE, UNION, ENUM, ENUM_VALUE, INPUT_OBJECT, INPUT_FIELD_DEFINITION

The directive `expand` callback continues to work for transforming
type definitions at compile time, and applied directives are now
visible through introspection queries.

Closes absinthe-graphql#1003

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: jwaldrip

lib/absinthe/blueprint/schema/enum_type_definition.ex

@@ -36,6 +36,7 @@ defmodule Absinthe.Blueprint.Schema.EnumTypeDefinition do
       values: values_by(type_def, :identifier),
       values_by_internal_value: values_by(type_def, :value),
       values_by_name: values_by(type_def, :name),
+      applied_directives: Blueprint.Schema.ObjectTypeDefinition.build_applied_directives(type_def.directives),
       definition: type_def.module,
       description: type_def.description
     }
@@ -52,7 +53,8 @@ defmodule Absinthe.Blueprint.Schema.EnumTypeDefinition do
             __reference__: value_def.__reference__,
             __private__: value_def.__private__,
             description: value_def.description,
-            deprecation: value_def.deprecation
+            deprecation: value_def.deprecation,
+            applied_directives: Blueprint.Schema.ObjectTypeDefinition.build_applied_directives(value_def.directives)
           }
 
           {Map.fetch!(value_def, key), value}

lib/absinthe/blueprint/schema/input_object_type_definition.ex

@@ -37,6 +37,7 @@ defmodule Absinthe.Blueprint.Schema.InputObjectTypeDefinition do
       name: type_def.name,
       fields: build_fields(type_def, schema),
       description: type_def.description,
+      applied_directives: Blueprint.Schema.ObjectTypeDefinition.build_applied_directives(type_def.directives),
       definition: type_def.module
     }
   end
@@ -49,6 +50,7 @@ defmodule Absinthe.Blueprint.Schema.InputObjectTypeDefinition do
         description: field_def.description,
         name: field_def.name,
         type: Blueprint.TypeReference.to_type(field_def.type, schema),
+        applied_directives: Blueprint.Schema.ObjectTypeDefinition.build_applied_directives(field_def.directives),
         definition: type_def.module,
         __reference__: field_def.__reference__,
         __private__: field_def.__private__,

lib/absinthe/blueprint/schema/interface_type_definition.ex

@@ -44,6 +44,7 @@ defmodule Absinthe.Blueprint.Schema.InterfaceTypeDefinition do
       fields: Blueprint.Schema.ObjectTypeDefinition.build_fields(type_def, schema),
       identifier: type_def.identifier,
       resolve_type: type_def.resolve_type,
+      applied_directives: Blueprint.Schema.ObjectTypeDefinition.build_applied_directives(type_def.directives),
       definition: type_def.module,
       interfaces: type_def.interfaces
     }

lib/absinthe/blueprint/schema/object_type_definition.ex

@@ -48,6 +48,7 @@ defmodule Absinthe.Blueprint.Schema.ObjectTypeDefinition do
       description: type_def.description,
       fields: build_fields(type_def, schema),
       interfaces: type_def.interfaces,
+      applied_directives: build_applied_directives(type_def.directives),
       definition: type_def.module,
       is_type_of: type_def.is_type_of,
       __private__: type_def.__private__
@@ -67,6 +68,7 @@ defmodule Absinthe.Blueprint.Schema.ObjectTypeDefinition do
         name: field_def.name,
         type: Blueprint.TypeReference.to_type(field_def.type, schema),
         args: build_args(field_def, schema),
+        applied_directives: build_applied_directives(field_def.directives),
         definition: field_def.module,
         __reference__: field_def.__reference__,
         __private__: field_def.__private__
@@ -85,6 +87,7 @@ defmodule Absinthe.Blueprint.Schema.ObjectTypeDefinition do
         type: Blueprint.TypeReference.to_type(arg_def.type, schema),
         default_value: arg_def.default_value,
         deprecation: arg_def.deprecation,
+        applied_directives: build_applied_directives(arg_def.directives),
         __reference__: arg_def.__reference__,
         __private__: arg_def.__private__
       }
@@ -93,6 +96,43 @@ defmodule Absinthe.Blueprint.Schema.ObjectTypeDefinition do
     end)
   end
 
+  @doc """
+  Converts Blueprint.Directive structs to a simple format for introspection.
+  """
+  def build_applied_directives(directives) when is_list(directives) do
+    Enum.map(directives, fn directive ->
+      %{
+        name: directive.name,
+        args: Enum.map(directive.arguments, fn arg ->
+          %{
+            name: arg.name,
+            value: serialize_argument_value(arg.input_value)
+          }
+        end)
+      }
+    end)
+  end
+
+  def build_applied_directives(_), do: []
+
+  defp serialize_argument_value(%Absinthe.Blueprint.Input.String{value: value}), do: inspect(value)
+  defp serialize_argument_value(%Absinthe.Blueprint.Input.Integer{value: value}), do: to_string(value)
+  defp serialize_argument_value(%Absinthe.Blueprint.Input.Float{value: value}), do: to_string(value)
+  defp serialize_argument_value(%Absinthe.Blueprint.Input.Boolean{value: value}), do: to_string(value)
+  defp serialize_argument_value(%Absinthe.Blueprint.Input.Null{}), do: "null"
+  defp serialize_argument_value(%Absinthe.Blueprint.Input.Enum{value: value}), do: value
+  defp serialize_argument_value(%Absinthe.Blueprint.Input.List{items: items}) do
+    "[" <> Enum.map_join(items, ", ", &serialize_argument_value/1) <> "]"
+  end
+  defp serialize_argument_value(%Absinthe.Blueprint.Input.Object{fields: fields}) do
+    "{" <> Enum.map_join(fields, ", ", fn field ->
+      "#{field.name}: #{serialize_argument_value(field.input_value)}"
+    end) <> "}"
+  end
+  defp serialize_argument_value(%Absinthe.Blueprint.Input.RawValue{content: content}), do: serialize_argument_value(content)
+  defp serialize_argument_value(%Absinthe.Blueprint.Input.Value{raw: raw}), do: serialize_argument_value(raw)
+  defp serialize_argument_value(value), do: inspect(value)
+
   defimpl Inspect do
     defdelegate inspect(term, options),
       to: Absinthe.Schema.Notation.SDL.Render

lib/absinthe/blueprint/schema/scalar_type_definition.ex

@@ -36,6 +36,7 @@ defmodule Absinthe.Blueprint.Schema.ScalarTypeDefinition do
       identifier: type_def.identifier,
       name: type_def.name,
       description: type_def.description,
+      applied_directives: Absinthe.Blueprint.Schema.ObjectTypeDefinition.build_applied_directives(type_def.directives),
       definition: type_def.module,
       serialize: type_def.serialize,
       parse: type_def.parse,

lib/absinthe/blueprint/schema/union_type_definition.ex

@@ -39,6 +39,7 @@ defmodule Absinthe.Blueprint.Schema.UnionTypeDefinition do
       identifier: type_def.identifier,
       types: type_def.types |> atomize_types(schema),
       fields: build_fields(type_def, schema),
+      applied_directives: Blueprint.Schema.ObjectTypeDefinition.build_applied_directives(type_def.directives),
       definition: type_def.module,
       resolve_type: type_def.resolve_type
     }
@@ -63,6 +64,7 @@ defmodule Absinthe.Blueprint.Schema.UnionTypeDefinition do
         name: field_def.name,
         type: Blueprint.TypeReference.to_type(field_def.type, schema),
         args: build_args(field_def, schema),
+        applied_directives: Blueprint.Schema.ObjectTypeDefinition.build_applied_directives(field_def.directives),
         definition: field_def.module,
         __reference__: field_def.__reference__,
         __private__: field_def.__private__
@@ -81,6 +83,7 @@ defmodule Absinthe.Blueprint.Schema.UnionTypeDefinition do
         type: Blueprint.TypeReference.to_type(arg_def.type, schema),
         default_value: arg_def.default_value,
         deprecation: arg_def.deprecation,
+        applied_directives: Blueprint.Schema.ObjectTypeDefinition.build_applied_directives(arg_def.directives),
         __reference__: arg_def.__reference__,
         __private__: arg_def.__private__
       }

lib/absinthe/type/argument.ex

@@ -35,6 +35,7 @@ defmodule Absinthe.Type.Argument do
             type: nil,
             deprecation: nil,
             default_value: nil,
+            applied_directives: [],
             definition: nil,
             __reference__: nil,
             __private__: []

lib/absinthe/type/built_ins/introspection.ex

@@ -94,6 +94,36 @@ defmodule Absinthe.Type.BuiltIns.Introspection do
   enum :__directive_location,
     values: Absinthe.Introspection.DirectiveLocation.values()
 
+  @desc "Represents a directive applied to a type, field, argument, or other schema element"
+  object :__applied_directive, name: "__AppliedDirective" do
+    field :name,
+      type: non_null(:string),
+      resolve: fn _, %{source: source} ->
+        {:ok, source.name}
+      end
+
+    field :args,
+      type: non_null(list_of(non_null(:__directive_argument))),
+      resolve: fn _, %{source: source} ->
+        {:ok, Map.get(source, :args, [])}
+      end
+  end
+
+  @desc "Represents an argument of an applied directive"
+  object :__directive_argument, name: "__DirectiveArgument" do
+    field :name,
+      type: non_null(:string),
+      resolve: fn _, %{source: source} ->
+        {:ok, source.name}
+      end
+
+    field :value,
+      type: non_null(:string),
+      resolve: fn _, %{source: source} ->
+        {:ok, source.value}
+      end
+  end
+
   object :__type do
     description "Represents scalars, interfaces, object types, unions, enums in the system"
 
@@ -214,6 +244,12 @@ defmodule Absinthe.Type.BuiltIns.Introspection do
         _, _ ->
           {:ok, nil}
       end
+
+    field :applied_directives,
+      type: non_null(list_of(non_null(:__applied_directive))),
+      resolve: fn _, %{source: source} ->
+        {:ok, Map.get(source, :applied_directives, [])}
+      end
   end
 
   object :__field do
@@ -277,6 +313,12 @@ defmodule Absinthe.Type.BuiltIns.Introspection do
         _, %{source: %{deprecation: dep}} ->
           {:ok, dep.reason}
       end
+
+    field :applied_directives,
+      type: non_null(list_of(non_null(:__applied_directive))),
+      resolve: fn _, %{source: source} ->
+        {:ok, Map.get(source, :applied_directives, [])}
+      end
   end
 
   object :__inputvalue, name: "__InputValue" do
@@ -327,6 +369,12 @@ defmodule Absinthe.Type.BuiltIns.Introspection do
         _, %{source: %{deprecation: dep}} ->
           {:ok, dep.reason}
       end
+
+    field :applied_directives,
+      type: non_null(list_of(non_null(:__applied_directive))),
+      resolve: fn _, %{source: source} ->
+        {:ok, Map.get(source, :applied_directives, [])}
+      end
   end
 
   object :__enumvalue, name: "__EnumValue" do
@@ -353,6 +401,12 @@ defmodule Absinthe.Type.BuiltIns.Introspection do
         _, %{source: %{deprecation: dep}} ->
           {:ok, dep.reason}
       end
+
+    field :applied_directives,
+      type: non_null(list_of(non_null(:__applied_directive))),
+      resolve: fn _, %{source: source} ->
+        {:ok, Map.get(source, :applied_directives, [])}
+      end
   end
 
   def render_default_value(schema, adapter, type, value) do

lib/absinthe/type/enum.ex

@@ -83,6 +83,7 @@ defmodule Absinthe.Type.Enum do
             values: %{},
             values_by_internal_value: %{},
             values_by_name: %{},
+            applied_directives: [],
             __private__: [],
             definition: nil,
             __reference__: nil

lib/absinthe/type/enum/value.ex

@@ -38,6 +38,7 @@ defmodule Absinthe.Type.Enum.Value do
             value: nil,
             deprecation: nil,
             enum_identifier: nil,
+            applied_directives: [],
             __reference__: nil,
             __private__: []
 end