Graphql-ruby: RuntimeError: No connection implementation to wrap ...

[egonm12]

Graphql version: 1.8.11

I am using graphlient (0.3.3) to write queries in my test. All queries run fine but when I write the query:

response = client.query do
  query do
    postsConnection do
      totalCount
    end
  end
end

I get this:

Failure/Error: result = KudosBackendSchema.execute(query, variables: variables, context: context, operation_name: operation_name)

     RuntimeError:
       No connection implementation to wrap Post::ActiveRecord_Relation (#<Post::ActiveRecord_Relation:0x00007f8ff4421888>)
     # ./app/controllers/graphql_controller.rb:14:in `execute'
     # ./spec/graphql/connections/posts_connection_spec.rb:18:in `block (2 levels) in <top (required)>'
     # ./spec/rails_helper.rb:59:in `block (3 levels) in <top (required)>'
     # ./spec/rails_helper.rb:58:in `block (2 levels) in <top (required)>'

I am assuming it's an issue of graphql and not from the graphlient gem. Any ideas what is causing this?

[rmosolgo]

Internally, GraphQL-Ruby tries to match _list objects_ (like Arrays and ActiveRecord::Relations) to _connection implementations_ (which provide cursor pagination etc) based on the object's class. GraphQL-Ruby has a built-in GraphQL::Relay::RelationConnection which is supposed to be matched to ActiveRecord::Relation, but for some reason ... it's not working here!

In fact, the gem couldn't find any connection wrapper for Post::ActiveRecord_Relation. What Rails version are you on? That looks like a generated class, so maybe some Rails version does things a bit differently?

[egonm12]

I am on the latest version of rails 5.2.1

[rmosolgo]

Hmmmm ... maybe for some reason the code to register the wrapper wasn't run, could you try adding this to your schema file? Add this line:

GraphQL::Relay::BaseConnection.register_connection_implementation(ActiveRecord::Relation, GraphQL::Relay::RelationConnection)

[egonm12]

Yess the test is passing! Any idea why it is not triggered in the test? The query is returning everything just fine in development env.

[rmosolgo]

Glad to hear it! Probably something to do with library load order, since graphql-ruby makes an if defined? check, that check might fail:

https://github.com/rmosolgo/graphql-ruby/blob/24d5c4bcf72f52a69086d63746a121564d44d117/lib/graphql/relay/relation_connection.rb#L179-L181