DataStore doesn't trigger update on item updated in a lambda trigger

[rossicler-hostalky]

Before opening, please confirm:

• I have searched for duplicate or closed issues and discussions.
• I have read the guide for submitting bug reports.
• I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.

JavaScript Framework

React Native

Amplify APIs

GraphQL API

Amplify Version

v6

Amplify Categories

api, function

Backend

Amplify CLI

Environment information

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Describe the bug

I have a DynamoDB trigger that updates an item, but DataStore is not properly triggering the update on the item.

I'm updating an attribute value along with _lastChangedAt, updatedAt and _version, and even tho I have n observer setup, it doesn't trigger. This is what I have for the observer:

const subscription = DataStore.observe<T>(
  modelConstructor,
  identifier
).subscribe((msg) => {
  console.log("Received a message", msg);
});

If I restart the app, after a second or so DataStore updates correctly.

Follow-up question: Is manually updating these DataStore metadata (_lastChangedAt, etc) recommended? If not, what is the right way?

Expected behavior

Print the log "Received a message " whenever the trigger updates the item on DynamoDB.

Reproduction steps

1. Initiate the observer on the client
2. Run a DynamoDB trigger or function that updates an item on DynamoDB.
3. Expect observer to get the updated item.

Code Snippet

// Put your code below this line.

Log output

// Put your logs below this line

aws-exports.js

No response

Manual configuration

No response

Additional configuration

No response

Mobile Device

No response

Mobile Operating System

No response

Mobile Browser

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Mobile Browser Version

No response

Additional information and screenshots

No response

[rossicler-hostalky]

Someone in the discord shared this documentation to help with my issue. But even after changing my function from updating directly in the database to using AppSync mutation to update, neither DataStore or AppSync Subscription is being triggered.

This is my client-side setup for testing:

const subTest = DataStore.observeQuery<T>(modelConstructor).subscribe(
  (snapshot) => console.log("[Test Object ObserverQuery]", snapshot)
);

const client = generateClient();
const subTest2 = client
  .graphql({ query: subcriptions.onUpdateRoom })
  .subscribe({
    next: (msg) => console.log("AppSync Subscription", msg),
    error: (err) => console.error("AppSync Subscription Error", err),
  });

My function looks like this:

...

const getRoomQuery = /* GraphQL */ `
  query GetRoom($id: ID!) {
    getRoom(id: $id) {
      id
      _version
    }
  }
`;

const updateRoomMutation = /* GraphQL */ `
  mutation UPDATE_ROOM($input: UpdateRoomInput!) {
    updateRoom(input: $input) {
      id
      lastMessageId
    }
  }
`;

const getRoomVersion = async (id) => {
  const res = await runGraphQLRequest(GRAPHQL_ENDPOINT, {
    query: getRoomQuery,
    variables: { id },
  });
  return res.data?.getRoom?._version;
};

/**
 * @type {import('@types/aws-lambda').APIGatewayProxyHandler}
 */
exports.handler = async (event) => {
  console.log(`EVENT: ${JSON.stringify(event)}`);
  for (const record of event.Records) {
    if (record.eventName !== "INSERT") continue;
    const doc = unmarshall(record.dynamodb.NewImage);

    const version = await getRoomVersion(doc.roomId);
    const variables = {
      input: {
        id: doc.roomId,
        lastMessageId: doc.id,
        _version: version,
      },
    };

    try {
      const res = await runGraphQLRequest(GRAPHQL_ENDPOINT, {
        query: updateRoomMutation,
        variables,
      });
      if (res.errors) {
        console.error("Errors: ", res.errors);
      } else {
        console.log("Success: ", JSON.stringify(res));
      }
    } catch (error) {
      console.error("Error:", error);
    }
  }
  return "Successfully processed DynamoDB record";
};

The function is running fine, I can see in DynamoDB that the value is updated. I can also see the Room updated if I restart the app (which forces DataStore to resync)