Support kotlin.collections.Set

[smyrick]

Is your feature request related to a problem? Please describe.
Right now the current support collections we can convert to a GraphQL list (List, Array) to do provide a uniqueness guarantee like Set

Describe the solution you'd like
We would like to use a Set<T> as a unique collection of values instead of a List<T> or Array<T>

Describe alternatives you've considered
We could use List in the schema code but then we would have to manually perform some operation to remove duplicates in the list

Additional context
This is the error that is thrown when Set is used in the schema

Cannot convert kotlin.collections.Set<kotlin.String> since it is outside the supported packages [com.expedia]

[smyrick]

Probably a better way rather than just adding Set to the list of things we can check is to find someway to support all Collections

https://github.com/ExpediaDotCom/graphql-kotlin/blob/0e6bc8aaa82a5805939313baa2d9285941d17577/src/main/kotlin/com/expedia/graphql/generator/TypeBuilder.kt#L52

[tapaderster]

Probably a better way rather than just adding Set to the list of things we can check is to find someway to support all Collections

@smyrick do you want to support all kotlin.Collections?

[smyrick]

@tapaderster The team brought up a good point that while Sets could be used from a server perspective that information is not part of the GraphQL spec so clients could pass in a list of items as input but if the server used a Set as the input then it would remove those items. The developer may want to do this but I feel like this would be an implementation detail and shouldn't be part of the schema serialization/deserialization.

My point being GraphQL really only supports lists, so we should as well. Does everyone agree?

[smyrick]

@ExpediaDotCom/graphql-kotlin Feedback anyone?

[dariuszkuc]

Since you cannot represent a set in GraphQL spec and there a builtins in the Kotlin lib to easily convert to/from set I'd not put any custom logic to schema generation to handle it.

[smyrick]

See updated discussion: #1110

You can add Set support with custom hooks