Datasources missing in the context when using subscriptions

Intended outcome: Context in the resolver functions will contain dataSources field when using subscriptions just like when calling with queries.

Actual outcome: Field dataSources is missing while using subscriptions in the context (in subscribe and resolve functions). The context contains everything except this one field.

How to reproduce the issue:

1. set dataSources to the server

const server = new ApolloServer({
    schema: Schema,
    dataSources: () => createDataSources(),
	// ...
})

1. dump content of the context:

subscribe: (parent, args, context) => {
    console.warn(context); // dataSources missing, every other field is there correctly
})

I think this is quite serious because otherwise, I cannot query my data sources at all while using subscriptions.

[martijnwalraven]

Unfortunately, this is a known issue. Although we run SubscriptionServer as part of ApolloServer, the request pipeline is completely separate. That means features like persisted queries, data sources, and tracing don’t currently work with subscriptions (or queries and mutations over the WebSocket transport).

There is work underway on a refactoring of the apollo-server-core request pipeline that will make it transport independent, and that will allow us to build the WebSocket transport on top of it. Until then, I’m afraid there isn’t much we can do.

[josedache]

I solved this by using @PatrickStrz method with some little tweak to have each Datasource instance to have the full context, Same way apollo server initializes its Datasources

const pubSub = new PubSub();

/**
 * Generate dataSources for both transport protocol
 */
function dataSources() {
  return {
    userService: new UserService(),
    ministryService: new MinistryService(),
    mailService: new MailService(),
  };
}

/**
 * Authenticate  subscribers on initial connect
 * @param {*} connectionParams 
 */
async function onWebsocketConnect(connectionParams) {
  const authUser = await authProvider.getAuthenticatedUser({
    connectionParams,
  });
  if (authUser) {
    return { authUser, pubSub, dataSources: dataSources() };
  }
  throw new Error("Invalid Credentials");
}

/**
 * Initialize subscribtion datasources
 * @param {Context} context 
 */
function initializeSubscriptionDataSources(context) {
  const dataSources = context.dataSources;
  if (dataSources) {
    for (const instance in dataSources) {
      dataSources[instance].initialize({ context, cache: undefined });
    }
  }
}

/**
 * Constructs the context for transport (http and ws-subscription) protocols
 */
async function context({ req, connection }) {
  if (connection) {
    const subscriptionContext = connection.context;
    initializeSubscriptionDataSources(subscriptionContext);
    return subscriptionContext;
  }

  const authUser = await authProvider.getAuthenticatedUser({ req });
  return { authUser, pubSub };
}

/**
 * Merges other files schema and resolvers to a whole
 */
const schema = makeExecutableSchema({
  typeDefs: [rootTypeDefs, userTypeDefs, ministryTypeDefs, mailTypeDefs],
  resolvers: [rootResolvers, userResolvers, ministryResolvers, mailResolvers],
});

/**
 * GraphQL server config
 */
const graphQLServer = new ApolloServer({
  schema,
  context,
  dataSources,
  subscriptions: {
    onConnect: onWebsocketConnect,
  },
});

Hope this helps 😃