export function printFilteredSchema

[Zemnmez]

It is useful to be able to print directives that are part of graphql's representation of the schema. Previous discussions on this have noted that printing directives as part of a schema doesn't make sense for a publicly accessible schema as they're not true parts of the 'graph' graphql represents.

However, I'm currently working with code generation tools, and not being able to print the full in-memory schema into canonical form is a deal breaker. printFilteredSchema already exposes the ability to adjust the way the schema is printed so this PR simply exposes it.

[IvanGoncharov]

@Zemnmez Issue that you referenced is about printing directive usage, not directive definitions.
The only thing that printFilteredSchema can do is to additionally print is definitions of @skip, @include and @deprecate:

graphql-js/src/utilities/__tests__/schemaPrinter-test.js

Lines 508 to 532 in 0d2220f

	"""
	Directs the executor to include this field or fragment only when the \`if\` argument is true.
	"""
	directive @include(
	"""Included when true."""
	if: Boolean!
	) on FIELD | FRAGMENT_SPREAD | INLINE_FRAGMENT
	"""
	Directs the executor to skip this field or fragment when the \`if\` argument is true.
	"""
	directive @skip(
	"""Skipped when true."""
	if: Boolean!
	) on FIELD | FRAGMENT_SPREAD | INLINE_FRAGMENT
	"""Marks an element of a GraphQL schema as no longer supported."""
	directive @deprecated(
	"""
	Explains why this element was deprecated, usually also including a suggestion
	for how to access supported similar data. Formatted using the Markdown syntax
	(as specified by [CommonMark](https://commonmark.org/).
	"""
	reason: String = "No longer supported"
	) on FIELD_DEFINITION | ENUM_VALUE

So are you sure that you want directive definitions and not directive usage?

[Zemnmez]

@IvanGoncharov oh... you're right. Is there a better way of doing what I'm trying to do? What I'm observing is that printSchema is not printing directives on my fields.

[IvanGoncharov]

@Zemnmez Proper solution is discussed in #2020
Currently, we are working on porting this library to TypeScript so we in a feature freeze until it's done.

As a temporary workaround you can do (NOT TESTED):

const sdl = printSchema(schema);
let currentType;
const modifiedAST = visit(parse(sdl), {
  ObjectDefinition(node) {
    currentType = schema.getType(node.name.value);
  },
  Field(node) {
    const fieldDef = currentType.getFields()[node.name.value];
    return {
      ...node,
      directives: fieldDef.astNode.directives,
    };
  },
});
const sdlWithDirectives = print(modifiedAST);

[Zemnmez]

thanks!