Expose attached schema directives through introspection

RELEASE.md

@@ -0,0 +1,23 @@
+---
+release type: minor
+social_messages:
+  x: >-
+    {project_name} {version} is out! Custom schema directives attached to types and
+    fields now appear in GraphQL introspection. 🍓
+    https://strawberry.rocks/release/{version}
+  linkedin: >-
+    {project_name} {version} is out. GraphQL tools can now discover custom schema
+    directives attached throughout a Strawberry schema using standard
+    introspection. 🍓
+---
+
+This release fixes introspection for custom schema directives.
+
+Schema directives attached to types, fields, arguments, and other schema elements
+now appear in standard GraphQL introspection. Schema explorers, IDEs, code
+generators, and other tools can discover each directive's description, arguments,
+allowed locations, repeatability, and any input types it uses.
+
+A directive reused across the schema is defined only once. Input, enum, and scalar
+types referenced by directive arguments are now part of the schema and may appear
+in generated SDL even when they are not used by fields.

strawberry/federation/schema.py

@@ -93,9 +93,17 @@ def __init__(  # noqa: PLR0917
             FederationAny: scalar(
                 name="_Any", serialize=lambda v: v, parse_value=lambda v: v
             ),
-            FieldSet: scalar(name="_FieldSet", serialize=lambda v: v, parse_value=str),
+            FieldSet: scalar(
+                name="_FieldSet",
+                serialize=lambda v: v,
+                parse_value=str,
+                print_definition=False,
+            ),
             LinkImport: scalar(
-                name="link__Import", serialize=lambda v: v, parse_value=lambda v: v
+                name="link__Import",
+                serialize=lambda v: v,
+                parse_value=lambda v: v,
+                print_definition=False,
             ),
         }
         if scalar_overrides:
@@ -367,6 +375,9 @@ def _warn_for_federation_directives(self) -> None:
 
         pass
 
+    def _should_register_schema_directive(self, directive: object) -> bool:
+        return True
+
 
 def _get_entity_type(
     query: type[WithStrawberryObjectDefinition] | None,

strawberry/federation/types.py

@@ -10,7 +10,7 @@
 """Represents an import for the @link directive."""
 
 
-@enum(name="link__Purpose")
+@enum(name="link__Purpose", print_definition=False)
 class LinkPurpose(Enum):
     SECURITY = "SECURITY"
     EXECUTION = "EXECUTION"

strawberry/printer/printer.py

@@ -10,7 +10,12 @@
     overload,
 )
 
-from graphql import GraphQLInputField, GraphQLObjectType, GraphQLSchema, is_union_type
+from graphql import (
+    GraphQLInputField,
+    GraphQLObjectType,
+    GraphQLSchema,
+    is_union_type,
+)
 from graphql.language.printer import print_ast
 from graphql.type import (
     is_enum_type,
@@ -592,6 +597,12 @@ def is_builtin_directive(directive: GraphQLDirective) -> bool:
     return False
 
 
+def _should_print_type(type_: GraphQLNamedType) -> bool:
+    strawberry_definition = type_.extensions.get("strawberry-definition")
+
+    return getattr(strawberry_definition, "print_definition", True)
+
+
 def print_schema(schema: BaseSchema) -> str:
     graphql_core_schema = cast(
         "GraphQLSchema",
@@ -609,7 +620,7 @@ def print_schema(schema: BaseSchema) -> str:
     types = [
         type_
         for type_name in sorted(type_map)
-        if is_defined_type(type_ := type_map[type_name])
+        if is_defined_type(type_ := type_map[type_name]) and _should_print_type(type_)
     ]
 
     types_printed = [_print_type(type_, schema, extras=extras) for type_ in types]
@@ -619,6 +630,7 @@ def print_schema(schema: BaseSchema) -> str:
         printed_directive
         for directive in filtered_directives
         if (printed_directive := print_directive(directive, schema=schema)) is not None
+        and printed_directive not in extras.directives
     ]
 
     if schema.config.enable_experimental_incremental_execution:
@@ -643,6 +655,9 @@ def _print_extra_types() -> Iterable[str]:
                 "GraphQLNamedType", schema.schema_converter.from_type(type_)
             )
 
+            if not _should_print_type(graphql_type):
+                continue
+
             # Skip types that are already part of the schema's type map, otherwise
             # they'd be printed twice (e.g. an enum used both as a regular type and
             # as a schema directive field), producing invalid SDL.