Query string argument should be a String -Rails Action Cable & graphql through apollo

I am using rails 6.1 graphql gem with Apollo to execute a subscription. It works for normal queries and mutations but rails complains about subscriptions.

In my frontend:

const cable = ActionCable.createConsumer( `${process.env.GATSBY_CABLE_URL}/cable?token=${localStorage.getItem('apiToken')}`, ); const actionCableLink = new ActionCableLink({ cable }); 

GraphQL channel in rails

# Channel used by the graphql schema class GraphqlChannel < ApplicationCable::Channel rescue_from StandardError, with: :report_error @op_name # To be called when a consumer subscribes to the GraphQL channel (ie when a user first opens the application). def subscribed # Store all GraphQL subscriptions the consumer is listening for on this channel @subscription_ids = [] end # To be called when a subscribed consumer registers for a subscription event on this channel. # This will be called once for every event the frontend wants to be notified about. def execute(data) query = data['query'] variables = ensure_hash(data['variables']) @op_name = data['operationName'] operation_name = data['operationName'] puts "Executing #{operation_name}" # puts "execute sub with query #{query}" context = { # Re-implement whatever context methods you need # in this channel or ApplicationCable::Channel # current_user: current_user, # Make sure the channel is in the context channel: self # https://medium.com/@jerridan/implementing-graphql-subscriptions-in-rails-and-react-9e05ca8d6b20 # Note that current_application_context has been added to the context object. # As I mentioned earlier, the Connection instance will be the parent of the GraphqlChannel instance, # so we can get any authorization details that were set in the Connection here. # current_application_context: connection.current_application_context } puts "executing schema query is a #{query.class}" result = ContentManagementSchema.execute({ query: query, context: context, variables: variables, operation_name: operation_name }) payload = { result: result.to_h, more: result.subscription? } puts "result is #{result}" # Track the subscription here so we can remove it # on unsubscribe. @subscription_ids << result.context[:subscription_id] if result.context[:subscription_id] transmit(payload) end # To be called when a consumer unsubscribes from the GraphQL channel (ie when a user closes the application). def unsubscribed # Delete all of the consumer's subscriptions from the GraphQL Schema @subscription_ids.each do |sid| ContentManagementSchema.subscriptions.delete_subscription(sid) end end private def report_error(e) puts "Error in graphql channel: #{e} - Op: #{@op_name}" end def ensure_hash(ambiguous_param) case ambiguous_param when String if ambiguous_param.present? ensure_hash(JSON.parse(ambiguous_param)) else {} end when Hash, ActionController::Parameters ambiguous_param when nil {} else raise ArgumentError, "Unexpected parameter: #{ambiguous_param}" end end end 

What happens is that in rails console I get:

 Executing PageComments 9:51:43 AM web.1 | executing schema query is a String 9:51:43 AM web.1 | Error in graphql channel: Query string argument should be a String, got Hash instead. - Op: SchedulePublishingStatus 9:51:43 AM web.1 | Error in graphql channel: Query string argument should be a String, got Hash instead. - Op: PageComments 

I searched for the error which I found in https://github.com/rmosolgo/graphql-ruby/blob/master/lib/graphql/query.rb which, unsurprisingly says that the query is a hash not a string. I don't really know how that is possible or how I can change this since I use apollos useSubscription hook in my frontend code:

 const { loading, error: subscriptionError } = useSubscription(PAGE_COMMENTS, { variables: { pageId }, onSubscriptionData: (res) => { setComments(res.subscriptionData.data.pageComments); }, }); 

 export const PAGE_COMMENTS = gql` subscription PageComments($pageId: ID) { pageComments(pageId: $pageId) { id body createdAt user { id email } } } `;