Adds `@tag` definition automatically in `buildSubgraphSchema` #1600

pcmanus · 2022-03-15T10:54:07Z

This patch makes @tag behave like any other federation directive in
subgraph-js/buildSubgraphSchema, that is, its definition is
automatically added to the schema.

But because we want to be "backward compatible", this patch also
ensure that federation directive definitions are not added by
buildSugraphSchema if the input document already defined a directive
with that name. Do note that while subrgaph-js has no validation
that such user definition of a federation directive is "correct",
this is ok because composition does do such validation and will
reject an invalid definition.

A consequence of this patch is that the @tag definition is not
outputed by printSubgraphSchema (like for other federation
directives), but it's very doubtful any external user would have
relied on this behaviour in the first place (and it's very easy
to adapt in the off chance someone does).

This patch makes `@tag` behave like any other federation directive in `subgraph-js`/`buildSubgraphSchema`, that is, its definition is automatically added to the schema. But because we want to be "backward compatible", this patch also ensure that federation directive definitions are not added by `buildSugraphSchema` if the input document already defined a directive with that name. Do note that while `subrgaph-js` has no validation that such user definition of a federation directive is "correct", this is ok because composition does do such validation and will reject an invalid definition. A consequence of this patch is that the `@tag` definition is not outputed by `printSubgraphSchema` (like for other federation directives), but it's very doubtful any external user would have relied on this behaviour in the first place (and it's very easy to adapt in the off chance someone does).

codesandbox-ci · 2022-03-15T10:55:01Z

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

pcmanus · 2022-03-15T11:01:08Z

subgraph-js/src/directives.ts

 ];

 export function isFederationDirective(directive: GraphQLDirective): boolean {
  return federationDirectives.some(({ name }) => name === directive.name);
 }

-export const otherKnownDirectives = [TagDirective];


Quick note for reviewers: an option could have been to keep that notion of "known but not officially federation" directives but have it empty for now. But if anything, we're trying to move away from hard-coded directives and toward @link-defined directives, so I'm almost certain this would never be used again, so removed it (in fact, #1554 is probably going to change all of this before GA anyway).

Agree that it's better to delete code that is unused rather than having it hand around!

benweatherman

🐐

benweatherman · 2022-03-15T12:31:22Z

subgraph-js/src/__tests__/buildSubgraphSchema.test.ts

+`);
+      };
+
+      it('adds it for fed1 schema', async () => {


nitpick/question We're saying that the tag directive is not added for fed1, right?

No, it's added. Though there is a little bit of subtlety here with what "fed1" means. Here we mean "fed1 schema that use subgraph-js 2.0+". People continuing to use subgraph-js 0.x won't have it added automatically however (it's a different branch altogether and I don't suggest we backport there).

We could have it not added for "fed1 schema handled by fed2 code" of course, but I'm essentially suggesting we don't bother because it's more code to have it happen (since currently subgraph-js don't really have logic distinguishing fed1 vs fed2 schema, it's pretty basic) and "fed1 schema handled by fed2 code" already have additional flexibility compared to "fed1 schema handled by fed1 code" so why not this.

clenfest

So I understand the individual pieces, but the reasons why this PR are necessary are a little fuzzy to me. Maybe worth spending a few minutes during the meeting today to give an overview.

clenfest · 2022-03-15T13:11:52Z

subgraph-js/src/buildSubgraphSchema.ts

@@ -67,7 +86,7 @@ export function buildSubgraphSchema(
    modules,
    new GraphQLSchema({
      query: undefined,
-      directives: [...specifiedDirectives, ...federationDirectives],
+      directives: [...specifiedDirectives, ...missingFederationDirectives(modules)],


So if I understand correctly, we are going through the AST to figure out which federation directives are not present and then passing them in a list? Can you explain why it isn't the federation directives that are present that we want?

When we visit the AST, we only look at directive definitions, not application. And what we're adding is the directives definition that don't already have a definition in the user provided schema.

We're not looking at applications at all. Which does mean we may be adding @provides definition even though it's never used by that particular schema, and we could well avoid it, but buildSubgraphSchema has always done that, adding all federation directive definition regardless of what is being used (which is harmless), and so keeping the code change focused.

The problem we're solving with this is that we want the @tag definition to be added automatically, like all other federation directive definitions, but the difference is that we historically have asked fed1 user to provide the definition themselves. So to be backward compatible, we just need to ensure we don't try to auto-add definitions that are already user defined, which wasn't something buildSubgraphSchema was previously bothering with.

clenfest · 2022-03-15T13:13:14Z

subgraph-js/src/buildSubgraphSchema.ts

@@ -30,6 +32,23 @@ type LegacySchemaModule = {

 export { GraphQLSchemaModule };

+function missingFederationDirectives(modules: GraphQLSchemaModule[]): GraphQLDirective[] {
+  // Copying the array as we're going to modify it.
+  const missingDirectives = federationDirectives.concat();


May not matter too much, but it would probably be better to use a set to avoid the O(n) lookup in a loop.

Well, it's one those rare case where the array size is not dynamic, we know exactly how many elements the array, it's a very small number and we kind of know it's never going to grow to a large number (relatively). So complexity argument kind of don't apply, and I'd be surprise if the array version is not as fast if not faster (but I agree it doesn't matter either way in practice).

clenfest · 2022-03-15T13:14:12Z

subgraph-js/src/directives.ts

 ];

 export function isFederationDirective(directive: GraphQLDirective): boolean {
  return federationDirectives.some(({ name }) => name === directive.name);
 }

-export const otherKnownDirectives = [TagDirective];


Agree that it's better to delete code that is unused rather than having it hand around!

clenfest · 2022-03-15T13:17:49Z

subgraph-js/src/__tests__/buildSubgraphSchema.test.ts

@@ -518,6 +518,50 @@ extend type User @key(fields: "email") {
 }
 `);
    });
+
+    describe('@tag directive', () => {


indent issue

clenfest · 2022-03-15T13:27:12Z

subgraph-js/src/__tests__/buildSubgraphSchema.test.ts

+`);
+      };
+
+      it('adds it for fed1 schema', async () => {


consider using it.each when you have multiple cases like this.

abernix requested review from clenfest and benweatherman March 15, 2022 10:58

abernix assigned pcmanus Mar 15, 2022

abernix changed the title ~~Adds @tag definition automatically in buildSubgraphSchema~~ Adds @tag definition automatically in buildSubgraphSchema Mar 15, 2022

pcmanus commented Mar 15, 2022

View reviewed changes

benweatherman approved these changes Mar 15, 2022

View reviewed changes

clenfest reviewed Mar 15, 2022

View reviewed changes

Sylvain Lebresne added 2 commits March 15, 2022 14:58

Fix placement of tests and use

35bafbe

Changelog updates

982ff6b

pcmanus merged commit a180100 into main Mar 15, 2022

pcmanus deleted the autoadd-tag-subgraphs branch March 15, 2022 15:12

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Adds `@tag` definition automatically in `buildSubgraphSchema` #1600

Adds `@tag` definition automatically in `buildSubgraphSchema` #1600

pcmanus commented Mar 15, 2022

codesandbox-ci bot commented Mar 15, 2022 •

edited

pcmanus Mar 15, 2022

clenfest Mar 15, 2022

benweatherman left a comment

benweatherman Mar 15, 2022

pcmanus Mar 15, 2022

clenfest left a comment

clenfest Mar 15, 2022

pcmanus Mar 15, 2022

clenfest Mar 15, 2022

pcmanus Mar 15, 2022

clenfest Mar 15, 2022

clenfest Mar 15, 2022

clenfest Mar 15, 2022

Adds @tag definition automatically in buildSubgraphSchema #1600

Adds @tag definition automatically in buildSubgraphSchema #1600

Conversation

pcmanus commented Mar 15, 2022

codesandbox-ci bot commented Mar 15, 2022 • edited

Choose a reason for hiding this comment

Choose a reason for hiding this comment

benweatherman left a comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

clenfest left a comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Adds `@tag` definition automatically in `buildSubgraphSchema` #1600

Adds `@tag` definition automatically in `buildSubgraphSchema` #1600

codesandbox-ci bot commented Mar 15, 2022 •

edited