Rails 6 Graphql ActionCable

README.md

I can't seem to get graphql subscriptions to work with the graphql gem and ActionCable 6.

The schema is able to be introspected and the following query:

subscription buildSub($buildUuid:String!) {
  build(uuid:$buildUuid) {
    uuid
    status
    success
    lastModified
  }
}

returns correctly in GraphiQL, but it uses controller, not the channel.

When I run the same query in GraphQL playground, it returns:

{
  "error": "Could not connect to websocket endpoint ws://localhost:3030/graphql. Please check if the endpoint url is correct."
}

And I get the following in my rails logs

Started GET "/graphql" for ::1 at 2019-08-29 14:36:22 -0600
Started GET "/graphql/" [WebSocket] for ::1 at 2019-08-29 14:36:22 -0600
Successfully upgraded to WebSocket (REQUEST_METHOD: GET, HTTP_CONNECTION: Upgrade, HTTP_UPGRADE: websocket)
Finished "/graphql/" [WebSocket] for ::1 at 2019-08-29 14:36:22 -0600

app-channels-graphq_channel.rb

class GraphqlChannel < ApplicationCable::Channel
  def subscribed
    @subscription_ids = []
  end

  def execute(data)
    Rails.logger.warn "!!! Executing !!!"
    query = data["query"]
    variables = ensure_hash(data["variables"])
    operation_name = data["operationName"]
    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,
    }

    result = Schema.execute({
      query: query,
      context: context,
      variables: variables,
      operation_name: operation_name
    })

    payload = {
      result: result.subscription? ? { data: nil } : result.to_h,
      more: result.subscription?,
    }

    # Track the subscription here so we can remove it
    # on unsubscribe.
    if result.context[:subscription_id]
      @subscription_ids << result.context[:subscription_id]
    end

    transmit(payload)
  end

  def unsubscribed
    @subscription_ids.each { |sid|
      Schema.subscriptions.delete_subscription(sid)
    }
  end

  private

  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

app-graphql-schema.rb

class Schema < GraphQL::Schema
  use GraphQL::Execution::Interpreter
  use GraphQL::Subscriptions::ActionCableSubscriptions

  subscription Types::SubscriptionType
end

app-graphql-subscriptions-build.rb

class Subscriptions::Build < GraphQL::Schema::Subscription
  argument :uuid, String, required: true
  payload_type Types::BuildType

  def subscribe(uuid:)
    Build.find(uuid)
  end
end

app-graphql-types-build_type.rb

class Types::BuildType < GraphQL::Schema::Object
  description 'A build'
  field :uuid, String, null: false
  field :status, String, null: false
  field :success, Boolean, null: true
  field :last_modified, Types::DateTimeType, null: true
end

app-graphql-types-subscription_type.rb

class Types::SubscriptionType < GraphQL::Schema::Object
  field :build, subscription: Subscriptions::Build
end