GraphiQL error when following graphql-ruby - Queries instructions

[SebastianSzturo]

If I follow current instructions in the graphql-ruby - Queries chapter I see following error in the GraphiQL console:

Error: Mutation fields must be an object with field names as keys or a function which returns such an object.
    at invariant (http://localhost:3000/assets/graphiql/rails/graphiql-0.10.2.self-b1f3838c6df9bb8fb4d30315dcdb431c4e3c5be8f8827635360232b8019d65bd.js?body=1:24179:11)
    at defineFieldMap (http://localhost:3000/assets/graphiql/rails/graphiql-0.10.2.self-b1f3838c6df9bb8fb4d30315dcdb431c4e3c5be8f8827635360232b8019d65bd.js?body=1:27207:27)
    at GraphQLObjectType.getFields (http://localhost:3000/assets/graphiql/rails/graphiql-0.10.2.self-b1f3838c6df9bb8fb4d30315dcdb431c4e3c5be8f8827635360232b8019d65bd.js?body=1:27164:44)
    at typeMapReducer (http://localhost:3000/assets/graphiql/rails/graphiql-0.10.2.self-b1f3838c6df9bb8fb4d30315dcdb431c4e3c5be8f8827635360232b8019d65bd.js?body=1:28869:25)
    at Array.reduce (<anonymous>)
    at new GraphQLSchema (http://localhost:3000/assets/graphiql/rails/graphiql-0.10.2.self-b1f3838c6df9bb8fb4d30315dcdb431c4e3c5be8f8827635360232b8019d65bd.js?body=1:28758:34)
    at buildClientSchema (http://localhost:3000/assets/graphiql/rails/graphiql-0.10.2.self-b1f3838c6df9bb8fb4d30315dcdb431c4e3c5be8f8827635360232b8019d65bd.js?body=1:30166:10)
    at http://localhost:3000/assets/graphiql/rails/graphiql-0.10.2.self-b1f3838c6df9bb8fb4d30315dcdb431c4e3c5be8f8827635360232b8019d65bd.js?body=1:2140:55
    at <anonymous>

This is due to rails generate graphql:install generating a schema that includes the mutation type, but at this point in the tutorial it is still empty.

GraphqlTutorialSchema = GraphQL::Schema.define do
  mutation(Types::MutationType)
  query(Types::QueryType)
end

We either need to make sure that we remove mutation(Types::MutationType) from this file before opening GraphiQL or adding a dummy mutation in this chapter.

I am not the best content writer, so I did not open a PR :P

[roberthopman]

@SebastianSzturo i got the same error, made a pull request for this, but the whole tutorial seems to be in need of an update :)

[conradwt]

@SebastianSzturo This issue has been resolved within graphql-ruby by PR #922

[nikolasburk]

Thanks for the discussion everyone 🙌