Updates to allow printing of Schema Directives

[Tyler-Gauch]

Overview

I have been working to get a working Apollo Federation server set up using this library. In doing so one of the requirements of Apollo Federation is that you need to serve the printed schema via the Query._service field, however, Apollo Federation relys heavily on schema directives and the current SchemaPrinter doesn't print any schema directives although the library allows adding them.

Problem

The current SchemaPrinter doesn't support printing Schema Directives

Example

Given schema:

directive @sd on OBJECT

type Bar @sd {
  foo: String
}

type Query {
  foo: Bar
}

SchemaPrinter::doPrint(...);
will print:

directive @sd on OBJECT

type Bar {
  foo: String
}

type Query {
  foo: Bar
}

Notice the missing @sd on Bar.

Solution

I added a piece of code similar to the interfaces printing in printObject which now prints Schema Directives

Testing

Added test cases for:

1. Schema Directive No Arguments
2. Schema Directive String Argument
3. Schema Directive Int Argument
4. Schema Directive Array Argument
5. Schema Directive with Type Arguments
6. Schema Directive Optional Arguments
7. Multiple Schema Directives
8. Schema Directive on a class with an interface
9. Schema Directive on an interface

[Tyler-Gauch]

If anyone has any ideas on why the pipeline keeps failing on composer dependencies that would be great thanks.

[simPod]

@Tyler-Gauch try again (eg. rebase on current master). I have just rebased my PR and it's all green.

[vladar]

Thank you for the PR!

But have you seen a discussion in #552 ? It is a bit more complicated than just printing directives. Long story short, we are waiting when this is resolved in graphql-js first to adopt the same approach.

So sadly, it is unlikely that this PR will make it into the master. I suggest following graphql/graphql-js#2020 and as soon as it is resolved - we can port the solution.

[simPod]

Suggested change

	public function testPrintSchemaDirectiveNoArgs()
	public function testPrintSchemaDirectiveNoArgs() : void

[simPod]

Suggested change

	public function testPrintSchemaDirectiveWithStringArgs()
	public function testPrintSchemaDirectiveWithStringArgs() : void

[simPod]

Suggested change

	public function testPrintSchemaDirectiveWithNumberArgs()
	public function testPrintSchemaDirectiveWithNumberArgs() : void

[simPod]

Suggested change

	public function testPrintSchemaDirectiveWithArrayArgs()
	public function testPrintSchemaDirectiveWithArrayArgs() : void

[simPod]

Suggested change

	self::assertEquals($exceptedSdl, $actual);
	self::assertSame($exceptedSdl, $actual);

[simPod]

Suggested change

	public function testPrintSchemaDirectiveOnInterface()
	public function testPrintSchemaDirectiveOnInterface() : void

[simPod]

Suggested change

	self::assertEquals($exceptedSdl, $actual);
	self::assertSame($exceptedSdl, $actual);

[simPod]

Is it possible to add some type hint for $directive?

[simPod]

I'd invert the condition so else is not hidden at the bottom: ' ' . $count === 0 ? '' : implode(

[simPod]

First two codnitions can be merged

[simPod]

@vladar Should we keep these PRs / issues open + add some label like waiting for reference impl or sth?

[vladar]

@simPod I think it will be a separate PR anyway, so yeah, let's close this.

[Tyler-Gauch]

Ahhhhhh I had not seen those other issues, good to know, thanks!