onUpdate Subscription throwing client errors

[kekami]

Environment information

System:
  OS: macOS 14.4.1
  CPU: (10) arm64 Apple M1 Max
  Memory: 170.11 MB / 32.00 GB
  Shell: /bin/zsh
Binaries:
  Node: 20.12.2 - ~/.nvm/versions/node/v20.12.2/bin/node
  Yarn: 3.8.2 - ~/.nvm/versions/node/v20.12.2/bin/yarn
  npm: 10.5.0 - ~/.nvm/versions/node/v20.12.2/bin/npm
  pnpm: undefined - undefined
NPM Packages:
  @aws-amplify/backend: 1.0.1
  @aws-amplify/backend-cli: 1.0.2
  aws-amplify: 6.2.0
  aws-cdk: 2.141.0
  aws-cdk-lib: 2.141.0
  typescript: 5.3.3
AWS environment variables:
  AWS_SDK_LOAD_CONFIG = 1
  AWS_STS_REGIONAL_ENDPOINTS = regional
  AWS_NODEJS_CONNECTION_REUSE_ENABLED = 1
No CDK environment variables

Description

Having issues getting subscription to work, when trying out the .onUpdate() subscription, I'm getting the following error message on the client. It works in the AppSync console.

TypeError: Cannot read properties of null (reading 'id')
    at APIClient.mjs:146:73
    at Array.map (<anonymous>)
    at APIClient.mjs:146:36
    at Array.map (<anonymous>)
    at initializeModel (APIClient.mjs:38:20)
    at subscription.mjs:23:12
    at map.js:9:7
    at OperatorSubscriber._this._next (OperatorSubscriber.js:18:21)
    at Subscriber.next (Subscriber.js:36:6)
    at Subscriber._next (Subscriber.js:65:16)

[kekami]

I debugged this. Problem can be found in:

@aws-amplify/data-schema/dist/esm/runtime/internals/operations/subscription.mjs

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
function subscriptionFactory(client, modelIntrospection, model, operation, getInternals) {
    const { name } = model;
    const subscription = (args) => {
        const query = generateGraphQLDocument(modelIntrospection, name, operation, args);
        const variables = buildGraphQLVariables(model, operation, args, modelIntrospection);
        const auth = authModeParams(client, getInternals, args);
        const headers = getCustomHeaders(client, getInternals, args?.headers);
        const observable = client.graphql({
            ...auth,
            query,
            variables,
        }, headers);
>>        return observable.pipe(map((value) => { <<<<< value contained { onEmployeeUpdate: { data: null, errors: [bunch of errrors] } }
            const [key] = Object.keys(value.data);
>>            const data = value.data[key];  <<<<< null
            const [initialized] = initializeModel(client, name, [data], modelIntrospection, auth.authMode, auth.authToken);
            return initialized;
        }));
    };
    return subscription;
}

The errors were essentially that createdAt, updatedAt, owner can't be null.

So a workaround was to change my mutation from

updateEmployee(input: $input) {
  id
  firstName
  lastName
}

to

updateEmployee(input: $input) {
  id
  createdAt
  updatedAt
  owner
  firstName
  lastName
}

If you need anything else don't hesitate to ping me

[kekami]

You might be wondering as well why I'm using updateEmployee. It's because I'm triggering it from EventBridge, e.g.

new aws_events.CfnRule(this, 'subscription', {
      eventBusName: props.eventBus.eventBusName,
      eventPattern: {
        'source': ['com.*****'],
        'detail-type': ['identity-verification.status'],
        'detail': {
          verifieraResult: {
            score: [{ numeric: ['=', 0] }],
          },
        },
      },
      roleArn: eventBusRole.roleArn,
      targets: [
        {
          id: 'appsyncBroadcastReceiver',
          arn: props.attrGraphQlEndpointArn,
          roleArn: eventBusRole.roleArn,
          appSyncParameters: {
            graphQlOperation: `
              mutation UpdateEmployeIdentityVerification($input: UpdateEmployeeInput!) {
                updateEmployee(input: $input) {
                  id
                  createdAt
                  updatedAt
                  owner
                  firstName
                  lastName
                }
              }`,
          },
          inputTransformer: {
            inputPathsMap: {
              id: '$.detail.userId',
              firstName: '$.detail.**********.firstName',
              lastName: '$.detail..**********.lastName',
            },
            inputTemplate: JSON.stringify({
              input: {
                id: '<id>',
                firstName: '<firstName>',
                lastName: '<lastName>',
              },
            }),
          },
        },
      ],
    });

[chrisbonifacio]

Hi @kekami reading the issue description, this sounds like the issue was with the hand written mutation in the EventBridge CDK code's selection set not matching the subscription's? You might have been able to adjust the selection set on the subscription itself like so:

await client.models.Employee.onUpdate({
  selectionSet: ["id", "firstName", "lastName"],
});