fix(GraphQL): fix for deletion on interfaces with no non Id field

[minhaj-shakeel]

Fixes GRAPHQL-655.

For this user schema (interface have no non-Id field):

interface A {
   name: String! @id
}

type B implements A {
  age: Int!
}

the following delete mutation

mutation{
  deleteA(filter:{name:{eq: "xyz"}}){
    a{
      name
    }
  }
}

was resulting in the following error:

{
  "errors": [
    {
      "message": "Internal Server Error - a panic was trapped.  This indicates a bug in the GraphQL server.  A stack trace was logged.  Please let us know by filing an issue with the stack trace."
    }
  ]
}

This PR fixes this bug and now deleting can be performed successfully.

---

This change is 

[pawanrawal]

Reviewable status: 0 of 3 files reviewed, 3 unresolved discussions (waiting on @MichaelJCompton, @minhaj-shakeel, and @pawanrawal)

---

graphql/resolve/delete_mutation_test.yaml, line 271 at r2 (raw file):

-
  name: "Deleting an interface with just a field with @id directive"

added this unit test for you

---

graphql/schema/wrappers.go, line 519 at r1 (raw file):

		default:
		}
		// This is a convoluted way of getting the type for mutatedTypeName. We get the definition

The whole comment needs to be updated as we don't get UpdateTPayload as the first choice anymore. Also, say that we use Delete as a backup and not Update because ....

---

graphql/schema/wrappers.go, line 525 at r1 (raw file):

		var def *ast.Definition
		if def = s.schema.Types["Add"+mutatedTypeName+"Payload"]; def == nil {
			def = s.schema.Types["Delete"+mutatedTypeName+"Payload"]

I hope we are not missing any case where Update is there but Add and Delete are not, should not be.

[minhaj-shakeel]

Reviewable status: 0 of 3 files reviewed, 3 unresolved discussions (waiting on @MichaelJCompton and @pawanrawal)

---

graphql/resolve/delete_mutation_test.yaml, line 271 at r2 (raw file):

Previously, pawanrawal (Pawan Rawal) wrote…

added this unit test for you

Thanks.

---

graphql/schema/wrappers.go, line 519 at r1 (raw file):

Previously, pawanrawal (Pawan Rawal) wrote…

The whole comment needs to be updated as we don't get UpdateTPayload as the first choice anymore. Also, say that we use Delete as a backup and not Update because ....

Done

---

graphql/schema/wrappers.go, line 525 at r1 (raw file):

Previously, pawanrawal (Pawan Rawal) wrote…

I hope we are not missing any case where Update is there but Add and Delete are not, should not be.

ok.

[pawanrawal]

Reviewed 2 of 2 files at r2, 1 of 1 files at r3.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @MichaelJCompton)