Using the `key` directive automatically defines types as extensions.

[Maldron]

Is there an existing issue for this?

• I have searched the existing issues

Current behavior

Adding a decorator like @Directive('@key(fields: "id")') to a class adds the extend keyword to the definition of the GraphQL type in the SDL.

As I understand it, adding the @key directive should define a type as an entity in the subgraph that owns that type. Additional subgraphs that reference a type owned by another subgraph need the extend keyword to indicate that they're extending an entity. This bug causes every type with a key to be treated as an extension, so there's no primary entity, which breaks federation.

Minimum reproduction code

https://github.com/Maldron/nest/tree/key_directive_automatically_makes_type_extension

Steps to reproduce

Linked repo is a fork of the nest repo with sample/23-graphql-code-first tweaked to act as a subgraph.

1. cd sample/23-graphql-code-first
2. npm install && npm run start
3. Grab the sdl through rover subgraph introspect http://localhost:3000/graphql or by running the following curl

curl --request POST \
  --url http://localhost:3000/graphql \
  --header 'Content-Type: application/json' \
  --data '{"query":"  query {\n    _service {\n      sdl\n    }\n  }"}'

It'll produce the following definition for Recipe:

extend type Recipe @key(fields: "id") {
  id: ID!
  title: String!
  description: String
  creationDate: Date!
  ingredients: [String!]!
}

Expected behavior

The Recipe type should be defined as an entity in the schema, not an extension. I.e.:

type Recipe @key(fields: "id") {
  id: ID!
  title: String!
  description: String
  creationDate: Date!
  ingredients: [String!]!
}

Package version

10.0.2

Graphql version

graphql: 16.3.0
apollo-server-express: 3.6.2

NestJS version

8.2.3

Node.js version

14.17.6

In which operating systems have you tested?

• macOS
• Windows
• Linux

Other

No response

[endroca]

Another problem is extend type Query. I can't extend the query

[Gamote]

Hi @kamilmysliwiec, we experience the same issue in our organization. To continue developing we're using this an ugly hack:

We created a patch that will update the @nestjs/graphql/dist/federation/graphql-federation.factory.js:123 file from:

if (key === '_service') {
    value.resolve = function resolve() {
        return {
            sdl: printSchema(autoGeneratedSchema).replace('type Query {', 'type Query @extends {')
              .replace('type Mutation {', 'type Mutation @extends {')
              .replace('type Subscription {', 'type Subscription @extends {')
...

to

if (key === '_service') {
    value.resolve = function resolve() {
        return {
            sdl: printSchema(autoGeneratedSchema).replace('type Query {', 'type Query @extends {')
              .replace('type Mutation {', 'type Mutation @extends {')
              .replace('type Subscription {', 'type Subscription @extends {')
              .replace('extend type User', 'type User') // <-- manually added
              .replace('extend type Wishlist', 'type Post'), // <-- manually added

We of course know that this is not something that we want in production, so I will be more than happy to create a PR with the fix if anyone can point me into the right direction as I couldn't find the place where the extend keyword is added based on the @key.

[kamilmysliwiec]

I've just tested this locally with our e2e tests. After removing the @Directive('@extends') (but leaving @Directive('@key...') in place:

Everything seems to work as expected

[Davide-Gheri]

@kamilmysliwiec I tested around this issue, the problem appears only using graphql@16:

@apollo/subgraph#printSubgraphSchema checks the presence of some fields to decide if the type should be extended or not, extensionASTNodes is one of them.

graphql@16 always includes extensionASTNodes in all GraphQLObjectType if nothing is provided,

while graphql@15 sets it as undefined

[kamilmysliwiec]

Thanks for looking into this @Davide-Gheri! So it seems that this issue comes from the Apollo library (@apollo/subgraph doesn't seem to be compatible with GraphQL v16). Is my assumption correct?

[endroca]

@kamilmysliwiec yes.

A version ago of apollo federation was being compatible with version 15.8.0, but apparently they have already updated

https://github.com/apollographql/federation/blob/main/subgraph-js/package.json#L27

[kamilmysliwiec]

@endroca note this is the package.json content of the alpha version https://github.com/apollographql/federation/blob/main/subgraph-js/package.json#L3 that is not yet stable.

As this issue doesn't seem to be related to this package, I think we should report it in the Apollo repository instead.

[vinaybedre]

@Maldron did you solved this issue? Do you mind sharing how did you do it?

[sgadzhalov]

Not fully tested, but I managed to get it working thanks to @Davide-Gheri's comment

      transformAutoSchemaFile: true,
      transformSchema: (schema) => {
        Object.keys(schema?.['_typeMap']).forEach((key) => {
          const type = schema?.['_typeMap']?.[key];
          type.extensionASTNodes =
            type.extensionASTNodes && type.extensionASTNodes.length > 0
              ? type.extensionASTNodes
              : undefined;
        });
        return schema;
      }