Fix #1834: Implement federation correctly

[newerbie]

Fix #1834
Fix #1724
Fix #1090
See also #1192

I have:

• Added tests covering the bug / feature (see testing)

---

There are several issues in federation implementation according to the Apollo Federation subgraph specification:

1. When customizing root query type, _service is not generated in customized query struct. Then Apollo gateway cannot get service definition in subgraph.
2. If @key directive is not used in graphql schema, both _service and _entities are not generated.

What did you expect?

1. _service is generated in customized query struct.
2. _service is generated in any case, while _entities is generated only when @key directive exists.

Minimal graphql.schema and models to reproduce

schema {
    query: CustomQuery
}

type Hello {
  name: String!
}

type CustomQuery {
  hello: Hello!
}

versions

• gqlgen version 0.15.1
• go version 1.17
• dep or go modules? go modules

[coveralls]

Coverage decreased (-0.09%) to 74.909% when pulling 78a0aea on newerbie:master into 9866507 on 99designs:master.

[StevenACoffman]

Hi! It looks like you need to run cd example; go generate ./... and commit the changes

[newerbie]

Hi! It looks like you need to run cd example; go generate ./... and commit the changes

Hi, I just reorganized the code related to line break generation, and after ran cd example; go generate ./..., nothing changed in all generated.go files, thanks for the tip.

[newerbie]

Hi! It looks like you need to run cd example; go generate ./... and commit the changes

Hi, I just reorganized the code related to line break generation, and after ran cd example; go generate ./..., nothing changed in all generated.go files, thanks for the tip.

I am so sorry it failed at lint stage again. I checked go:generate throughout the project, and ran go generate ./... again, there were two added line breaks in plugin/federation/testdata/entityresolver/generated/exec.go. I think it's ok now.

[StevenACoffman]

Thanks!