[Bug] Allow type to implement interfaces with same fields

Issues GraphQL
1

Schema:

interface IsBar {
   id: String! @id
}

interface IsBaz {
   id: String! @id
}

type Foo implements IsBar & IsBaz {
   value: String!
}

Posting this to dgraph results in following error:

resolving updateGQLSchema failed because input: Field Foo.id can only be defined once.

It seems that the fields from all implemented interfaces are just copied over to the implementing type.
Instead I would expect that this will only be done when the field doesn’t exist already!

By the way, I wouldn’t need this if it would finally be possible for interfaces to implement other interfaces!

1 Like
2

I think that is a graphql spec problem, as it would have more than one id, which is forbidden.

J

3

Thats my point - dgraph seems to derive a type:

type Foo {
   id: String! @id
   id: String! @id
}

which it shouldn’t.

1 Like
4

Ah, good point. Should be fixed, @id can have multiple but ID can’t.

@MichelDiz - Probably a bug?

J

1 Like
5

that(the last one) looks like a bug to me. @aman-bansal @dmai ?

@maaft can you change or create a new ticket for this last one?

6

Just to be clear, @id is not the issue here.

@MichelDiz I’m not sure what you mean. Could you read again? The issue is fully explained in my first post and Jonathan did not discover another issue.

7

Just trying to understand here, I see two issues:

  1. If two interfaces defined the same field, node type should only consider one. I think this can be easily fixed.
  2. What if both the interfaces have different id fields. what would be the expectation in this case ? I believe the expectation would be something like composite keys?
8

Aren’t multiple @id fields already supported without issues? Where do you see problems?

Or are you talking about multiple ID types with different names? I don’t see a use-case for this currently, so it could just be disallowed and an error could be thrown when posting the schema.