# Subscription error in handler with expressAppFromMiddleware

**URL:** <https://community.apollographql.com/t/subscription-error-in-handler-with-expressappfrommiddleware/5742>\
**Category:** Server\
**Tags:** server\
**Created:** [February 16, 2023, 3:04pm UTC](https://community.apollographql.com/t/subscription-error-in-handler-with-expressappfrommiddleware/5742 "2023-02-16T15:04:56Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Aymeric\_Bertrand](https://sea1.discourse-cdn.com/flex019/user_avatar/community.apollographql.com/aymeric_bertrand/32/3718_2.png) [@Aymeric\_Bertrand](https://community.apollographql.com/u/Aymeric_Bertrand)\
**Post date:** [February 16, 2023, 3:04pm UTC](https://community.apollographql.com/t/subscription-error-in-handler-with-expressappfrommiddleware/5742/1 "2023-02-16T15:04:56Z")

</div>

Hello friends.

I try to realize a graphql subscription in lambda with createHandler function but it doesn’t work. I use serverless to deploy and serverless-offline to develop. And I use neo4j/graphql library to autogenerate the graphql resolvers.

The handler fonction is created by this code :

```auto
import { createServer } from "http";
import express from "express";
import { ApolloServer, gql } from "apollo-server-lambda";
import { WebSocketServer } from "ws"; 
import { useServer } from "graphql-ws/lib/use/ws"; 
import DatabaseManager from "../../services/database/DatabaseManager";
import { Neo4jGraphQL, Neo4jGraphQLSubscriptionsSingleInstancePlugin } from "@neo4j/graphql";
import { ApolloServerPluginDrainHttpServer } from "apollo-server-core";

const typeDefs = gql`
  type Movie {
    title: String!
    description: String!
  }
`;

const driver = DatabaseManager.driver;

const neoSchema = new Neo4jGraphQL({
  typeDefs,
  driver,
  plugins: {
    subscriptions: new Neo4jGraphQLSubscriptionsSingleInstancePlugin(),
  },
});

const app = express();
const httpServer = createServer(app);

const wsServer = new WebSocketServer({
  server: httpServer,
  path: "/graphql",
});

const initServer = () => {
  return neoSchema.getSchema().then(async (schema) => {
    const serverCleanup = useServer({ schema }, wsServer);

    const server = new ApolloServer({
      schema,
      context: ({ event }) => ({ req: { headers: event.headers } }),
      plugins: [
        ApolloServerPluginDrainHttpServer({
          httpServer,
        }),
        {
          async serverWillStart() {
            return {
              async drainServer() {
                await serverCleanup.dispose();
              },
            };
          },
        },
      ],
    });

    // If I try :
    //await server.start()
    //I have this error => //Error: When using an ApolloServer subclass from a serverless framework package, you don't need to call start(); just call createHandler().

    // If I try :
    //server.applyMiddleware({app})
    // I have this error => //Error: You must `await server.start()` before calling `server.applyMiddleware()`
    // Then i try to use expressAppFromMiddleware() function to passed app server as middleware.

    const handlerMiddleware = server.createHandler({
      expressGetMiddlewareOptions: {
        cors: {
          origin: "*",
          credentials: true,
        },
      },
      expressAppFromMiddleware(middleware) {
        app.use(middleware);
        return app;
      },
    });

    return handlerMiddleware;
  });
};

export const handler = async (event: any, context: any, callback: any) => {
  const serverHandler = await initServer();

  return serverHandler({ ...event }, context, callback);
};

```

When i use [Studio](https://studio.apollographql.com/sandbox/explorer), I can see the root subscription

 ![Capture d’écran 2023-02-16 à 12.37.56](https://us1.discourse-cdn.com/flex019/uploads/apollographql/original/2X/e/e2db86a00c1fa5ff4134a1e2b71498208cfc8f26.png)

I tested to create Movies with Postman (POST http ://localhost:4242/channel-subscription)  
with graphQL body :

```auto
mutation CreateMovies($input: [MovieCreateInput!]!) {
  createMovies(input: $input) {
    movies {
      description
      title
    }
  }
}

```

and with variables :

```auto
{
  "input": [
    {
      "title": "new film",
      "description": "I am description"
    }
  ]
}

```

The result of createdMovie is : **Status 200 OK**  
And the response is :

```auto
{
    "data": {
        "createMovies": {
            "movies": [
                {
                    "description": "I am description",
                    "title": "new film"
                }
            ]
        }
    }
}

```

Queries also works.

But when I try to realize Subscription with Postman (POST http ://localhost:4242/channel-subscription)  
with graphQL body :

```auto
subscription MovieCreated($where: MovieSubscriptionWhere) {
  movieCreated(where: $where) {
    event
    timestamp
    createdMovie {
      title
      description
    }
  }
}

```

and with variables :

```auto
{
  "where": {
    "title": "title of new film for subscription test"
  }
}

```

the result of subscription return:

> {  
> “errors”: [  
> {  
> “message”: “Payload is undefined. Can’t call subscriptions resolver directly.”,  
> “rentals”: [  
> {  
> “line”: 2,  
> column: 3  
> }  
> ],  
> “path”: [  
> “movieCreated”  
> ],  
> “extensions”: {  
> “code”: “INTERNAL\_SERVER\_ERROR”,  
> “exception”: {  
> “stacktrace”: [  
> “Error: Payload is undefined. Can’t call subscriptions resolver directly.”,  
> " at subscriptionResolve (/Users/Aymeric/my-projects/node\_modules/@neo4j/graphql/dist/schema/resolvers/subscriptions/subscribe.js:30:15)“,  
> " at /Users/Aymeric/my-projects/node\_modules/@neo4j/graphql/dist/schema/resolvers/wrapper.js:114:12”,  
> " at field.resolve (/Users/Aymeric/my-projects/node\_modules/apollo-server-core/dist/utils/schemaInstrumentation.js:56:26)“,  
> " at executeField (/Users/Aymeric/my-projects/node\_modules/graphql/execution/execute.js:481:20)”,  
> " at executeFields (/Users/Aymeric/my-projects/node\_modules/graphql/execution/execute.js:413:20)“,  
> " at executeOperation (/Users/Aymeric/my-projects/node\_modules/graphql/execution/execute.js:358:14)”,  
> " at execute (/Users/Aymeric/my-projects/node\_modules/graphql/execution/execute.js:136:20)“,  
> " at execute (/Users/Aymeric/my-projects/node\_modules/apollo-server-core/dist/requestPipeline.js:205:48)”,  
> " at processGraphQLRequest (/Users/Aymeric/my-projects/node\_modules/apollo-server-core/dist/requestPipeline.js:148:34)“,  
> " at processTicksAndRejections (internal/process/task\_queues.js:95:5)”,  
> " at async processHTTPRequest (/Users/Aymeric/my-projects/node\_modules/apollo-server-core/dist/runHttpQuery.js:221:30)"  
> ]  
> }  
> }  
> }  
> ],  
> “data”: null

I think I have a problem with expressAppFromMiddleware , but I don’t understand where is my error

I specify the code in my serverless.yml who create the function is :

```auto
functions:
    channel-subscription:
        handler: ./src/functions/channel-subscription.handler
        description: test subscription with appolo server
        events:
          - http:
              path: /channel-subscription
              method: post
              cors: true
          - http:
              path: /graphql
              method: post
              cors: true

```