amplify-js: DataStore saves inconsistent data to dynamoDB on a poor connection

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

Amplify APIs

GraphQL API, DataStore

Amplify Categories

api

Environment information

  System:
    OS: Linux 5.18 Arch Linux
    CPU: (16) x64 AMD Ryzen 7 3700X 8-Core Processor
    Memory: 17.56 GB / 31.26 GB
    Container: Yes
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 16.13.2 - ~/.nvm/versions/node/v16.13.2/bin/node
    Yarn: 1.22.19 - /usr/bin/yarn
    npm: 8.1.2 - ~/.nvm/versions/node/v16.13.2/bin/npm
  Browsers:
    Firefox: 101.0.1
  npmPackages:
    @aws-amplify/ui-react: ^2.19.1 => 2.19.1
    @aws-amplify/ui-react-internal:  undefined ()
    @aws-amplify/ui-react-legacy:  undefined ()
    @peculiar/webcrypto: ^1.3.2 => 1.3.2
    @testing-library/jest-dom: ^5.16.2 => 5.16.2
    @testing-library/react: ^12.1.4 => 12.1.4
    @testing-library/user-event: ^13.5.0 => 13.5.0
    aws-amplify: ^4.3.24 => 4.3.24
    graphql: ^16.3.0 => 16.3.0 (15.8.0)
    react: ^17.0.2 => 17.0.2
    react-dom: ^17.0.2 => 17.0.2
    react-scripts: 5.0.0 => 5.0.0
    web-vitals: ^2.1.4 => 2.1.4
  npmGlobalPackages:
    @aws-amplify/cli: 8.4.0
    corepack: 0.10.0
    npm: 8.1.2

Describe the bug

When making changes too fast to a record, mutations to the API are missed or send incorrect data.

An observer will also react and return the UI into an old state that reflects the out of date mutation.

The problem is more obvious when on a slow network connection, and in real world testing has caused data to be saved incorrectly with normal usage. When offline, data is synced correctly once a connection is re-established.

I also find the problem occurs when testing with Cypress at full network speed.

I use an observer to make sure that the record has one field set before enabling a button to set the next field. However I have observed this issue when changing a single field repeatedly.

One workaround is to check that _version has incremented before allowing further mutations. However this prevents it from working offline as that value is never incremented until data is sent to the API.

In my example I’m setting two fields: status and a time stamp. But it does seem to happen when setting one field too.

Expected behavior

DataStore should always sync changes to the record and not miss changes. The observer should not update with incorrect data.

Reproduction steps

open the example in Chrome
open dev tools and in the console: await DataStore.save(new models.Task({}))
copy the new ID to taskId
(if console says task not found, refresh the page)
go to Network tab. Change No throttling to Slow 3G
update the record by clicking the check boxes multiple times. previous check box should be disabled until the observer updates
the status should appear at the top
buttons that are enabled appear under the checkboxes
observe mutations in the Network tab
observe changes in the UI

Code Snippet


enum TaskStatus {
  ACTIVE
  PICKED_UP
  DROPPED_OFF
  COMPLETED
}

type Task @model @auth(rules: [{ allow: public }]) {
  id: ID!
  status: TaskStatus
  timePickedUp: AWSDateTime
  timeDroppedOff: AWSDateTime
  timeRiderHome: AWSDateTime
}

src/App.js

import "./App.css";
import React, { useRef, useState } from "react";
import { Amplify, DataStore } from "aws-amplify";
import awsconfig from "./aws-exports";
import { useEffect } from "react";
import * as models from "./models";

window.DataStore = DataStore;
window.models = models;
Amplify.configure(awsconfig);

const fields = {
  timePickedUp: "Picked up",
  timeDroppedOff: "Delivered",
  timeRiderHome: "Rider home",
};

export const tasksStatus = {
  active: "ACTIVE",
  pickedUp: "PICKED_UP",
  droppedOff: "DROPPED_OFF",
  completed: "COMPLETED",
};

export function determineTaskStatus(task) {
  if (!!!task.timePickedUp) {
    return tasksStatus.active;
  } else if (!!task.timePickedUp && !!!task.timeDroppedOff) {
    return tasksStatus.pickedUp;
  } else if (
    !!task.timePickedUp &&
    !!task.timeDroppedOff &&
    !!!task.timeRiderHome
  ) {
    return tasksStatus.droppedOff;
  } else if (
    !!task.timePickedUp &&
    !!task.timeDroppedOff &&
    !!task.timeRiderHome
  ) {
    return tasksStatus.completed;
  }
}

async function saveTaskTimeWithKey(key, value, taskId) {
  let isoString = null;
  if (value) {
    isoString = new Date(value).toISOString();
  }
  const existingTask = await DataStore.query(models.Task, taskId);
  if (!existingTask) throw new Error("Task doesn't exist");
  const status = await determineTaskStatus({
    ...existingTask,
    [key]: isoString,
  });
  return DataStore.save(
    models.Task.copyOf(existingTask, (updated) => {
      updated[key] = value ? isoString : null;
      updated.status = status;
    })
  );
}

function App() {
  const [state, setState] = useState([]);
  const [task, setTask] = useState(null);
  const [isPosting, setIsPosting] = useState(false);
  const taskObserver = useRef({ unsubscribe: () => {} });
  const timeSet = useRef(null);
  const taskId = "38b35b73-2b4a-406a-bcf0-de0bc56ee8d0";
  const prevVersion = useRef(null);

  function checkDisabled(key) {
    const stopped =
      state.includes("timeCancelled") || state.includes("timeRejected");
    if (key === "timeDroppedOff")
      return (
        state.includes("timeRiderHome") ||
        !state.includes("timePickedUp") ||
        stopped
      );
    else if (key === "timePickedUp") {
      return state.includes("timeDroppedOff") || stopped;
    } else if (key === "timeRiderHome") {
      if (task && task.status === tasksStatus.new) return true;
      return !state.includes("timeDroppedOff");
    } else if (key === "timeRejected") {
      if (state.includes("timeRejected")) return false;
      return (
        (state.includes("timePickedUp") && state.includes("timeDroppedOff")) ||
        stopped
      );
    } else if (key === "timeCancelled") {
      if (state.includes("timeCancelled")) return false;
      return (
        (state.includes("timePickedUp") && state.includes("timeDroppedOff")) ||
        stopped
      );
    } else return false;
  }

  async function setTimeWithKey(key, value) {
    try {
      setIsPosting(true);
      await saveTaskTimeWithKey(key, value, taskId);
      setIsPosting(false);
    } catch (error) {
      console.log(error);
    }
  }

  async function getTaskAndUpdateState() {
    try {
      const task = await DataStore.query(models.Task, taskId);
      if (!task) throw new Error("Task not found");
      setTask(task);
      taskObserver.current.unsubscribe();
      taskObserver.current = DataStore.observe(models.Task, taskId).subscribe(
        async ({ opType, element }) => {
          if (
            ["INSERT", "UPDATE"].includes(opType)
            // uncomment for a fix that only works while online
            //&& element._version > prevVersion.current
          ) {
            console.log(element);
            setTask(element);
            prevVersion.current = element._version;
          }
        }
      );
    } catch (e) {
      console.log(e);
    }
  }
  useEffect(() => getTaskAndUpdateState(), []);

  function calculateState() {
    if (!task) return;
    const result = Object.keys(fields).filter((key) => {
      return !!task[key];
    });
    setState(result);
  }
  useEffect(calculateState, [task]);

  function onClickToggle(key, checked) {
    timeSet.current = new Date();
    setTimeWithKey(key, !checked ? null : new Date());
  }

  return (
    <div>
      {task ? task.status : ""}
      <div>
        <form class="form">
          {Object.entries(fields).map(([key, label]) => {
            return (
              <label>
                {label}
                <input
                  type="checkbox"
                  disabled={isPosting || checkDisabled(key)}
                  onChange={(e) => onClickToggle(key, e.target.checked)}
                  checked={state.includes(key)}
                />
              </label>
            );
          })}
        </form>
      </div>
      <div sx={{ width: "100%" }} direction="column">
        {Object.entries(fields).map(([key, value]) => {
          const disabled = isPosting || checkDisabled(key);
          return (
            !disabled && (
              <div>
                {value.toUpperCase()}
              </div>
            )
          );
        })}
      </div>
    </div>
  );
}

export default App;

src/App.css

.form {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: flex-end;
  max-width: 120px;
}

Log output


ConsoleLogger.ts:125 [DEBUG] 01:01.814 DataStore - params ready {predicate: {…}, pagination: {…}, modelConstructor: ƒ}
App.js:126 Model {id: '38b35b73-2b4a-406a-bcf0-de0bc56ee8d0', status: 'DROPPED_OFF', timePickedUp: '2022-06-10T01:52:35.587Z', timeDroppedOff: '2022-06-10T02:00:34.696Z', timeCancelled: null, …}
ConsoleLogger.ts:115 [DEBUG] 01:01.852 DataStore - Attempting mutation with authMode: API_KEY
ConsoleLogger.ts:115 [DEBUG] 01:01.852 Util -  attempt #1 with this vars: ["Task","Update","{\"timeRiderHome\":null,\"status\":\"DROPPED_OFF\",\"id\":\"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0\",\"_version\":316,\"_lastChangedAt\":1654826451258,\"_deleted\":null}","{}",null,null,{"data":"{\"timeRiderHome\":null,\"status\":\"DROPPED_OFF\",\"id\":\"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0\",\"_version\":316,\"_lastChangedAt\":1654826451258,\"_deleted\":null}","modelId":"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0","model":"Task","operation":"Update","condition":"{}","id":"01G55M7Q5TB189H8P2QFKV0F35"}]
ConsoleLogger.ts:125 [DEBUG] 01:01.853 RestClient - POST https://xpbl3vag25afng2n6ishxbo74y.appsync-api.eu-west-1.amazonaws.com/graphql
ConsoleLogger.ts:125 [DEBUG] 01:02.110 DataStore - params ready {predicate: {…}, pagination: {…}, modelConstructor: ƒ}
App.js:126 Model {id: '38b35b73-2b4a-406a-bcf0-de0bc56ee8d0', status: 'PICKED_UP', timePickedUp: '2022-06-10T01:52:35.587Z', timeDroppedOff: null, timeCancelled: null, …}
ConsoleLogger.ts:115 [DEBUG] 01:02.145 AWSAppSyncRealTimeProvider - subscription message from AWS AppSync RealTime: {"id":"55de9349-e5e3-4391-9ff0-daa8235c61a2","type":"data","payload":{"data":{"onUpdateTask":{"id":"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0","status":"DROPPED_OFF","timePickedUp":"2022-06-10T01:52:35.587Z","timeDroppedOff":"2022-06-10T02:00:34.696Z","timeCancelled":null,"timeRejected":null,"timeRiderHome":null,"createdAt":"2022-06-09T18:38:06.466Z","updatedAt":"2022-06-10T02:01:01.912Z","_version":317,"_lastChangedAt":1654826461927,"_deleted":null}}}}
ConsoleLogger.ts:118 [DEBUG] 01:02.145 AWSAppSyncRealTimeProvider {id: '55de9349-e5e3-4391-9ff0-daa8235c61a2', observer: SubscriptionObserver, query: 'subscription operation {\n  onUpdateTask {\n    id\n …  _version\n    _lastChangedAt\n    _deleted\n  }\n}\n', variables: {…}}
ConsoleLogger.ts:125 [DEBUG] 01:02.384 DataStore - params ready {predicate: {…}, pagination: {…}, modelConstructor: ƒ}
App.js:126 Model {id: '38b35b73-2b4a-406a-bcf0-de0bc56ee8d0', status: 'ACTIVE', timePickedUp: null, timeDroppedOff: null, timeCancelled: null, …}
ConsoleLogger.ts:115 [DEBUG] 01:03.886 DataStore - Mutation sent successfully with authMode: API_KEY
ConsoleLogger.ts:115 [DEBUG] 01:03.909 DataStore - Attempting mutation with authMode: API_KEY
ConsoleLogger.ts:115 [DEBUG] 01:03.909 Util -  attempt #1 with this vars: ["Task","Update","{\"id\":\"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0\",\"_version\":316,\"_lastChangedAt\":1654826451258,\"_deleted\":null,\"timeDroppedOff\":null,\"status\":\"ACTIVE\",\"timePickedUp\":null}","{}",null,null,{"data":"{\"id\":\"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0\",\"_version\":316,\"_lastChangedAt\":1654826451258,\"_deleted\":null,\"timeDroppedOff\":null,\"status\":\"ACTIVE\",\"timePickedUp\":null}","modelId":"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0","model":"Task","operation":"Update","condition":"{}","id":"01G55M7Q5TB189H8P2QFKV0F37"}]
ConsoleLogger.ts:125 [DEBUG] 01:03.910 RestClient - POST https://xpbl3vag25afng2n6ishxbo74y.appsync-api.eu-west-1.amazonaws.com/graphql
ConsoleLogger.ts:115 [DEBUG] 01:04.214 AWSAppSyncRealTimeProvider - subscription message from AWS AppSync RealTime: {"id":"55de9349-e5e3-4391-9ff0-daa8235c61a2","type":"data","payload":{"data":{"onUpdateTask":{"id":"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0","status":"DROPPED_OFF","timePickedUp":"2022-06-10T01:52:35.587Z","timeDroppedOff":"2022-06-10T02:00:34.696Z","timeCancelled":null,"timeRejected":null,"timeRiderHome":null,"createdAt":"2022-06-09T18:38:06.466Z","updatedAt":"2022-06-10T02:01:01.912Z","_version":318,"_lastChangedAt":1654826464061,"_deleted":null}}}}
ConsoleLogger.ts:118 [DEBUG] 01:04.214 AWSAppSyncRealTimeProvider {id: '55de9349-e5e3-4391-9ff0-daa8235c61a2', observer: SubscriptionObserver, query: 'subscription operation {\n  onUpdateTask {\n    id\n …  _version\n    _lastChangedAt\n    _deleted\n  }\n}\n', variables: {…}}
ConsoleLogger.ts:115 [DEBUG] 01:05.927 DataStore - Mutation sent successfully with authMode: API_KEY
App.js:126 Model {id: '38b35b73-2b4a-406a-bcf0-de0bc56ee8d0', status: 'DROPPED_OFF', timePickedUp: '2022-06-10T01:52:35.587Z', timeDroppedOff: '2022-06-10T02:00:34.696Z', timeCancelled: null, …}
ConsoleLogger.ts:115 [DEBUG] 01:10.215 AWSAppSyncRealTimeProvider - subscription message from AWS AppSync RealTime: {"type":"ka"}
ConsoleLogger.ts:118 [DEBUG] 01:10.228 AWSAppSyncRealTimeProvider {id: '', observer: null, query: '', variables: {…}}
ConsoleLogger.ts:125 [DEBUG] 02:04.837 DataStore - params ready {predicate: {…}, pagination: {…}, modelConstructor: ƒ}
App.js:126 Model {id: '38b35b73-2b4a-406a-bcf0-de0bc56ee8d0', status: 'COMPLETED', timePickedUp: '2022-06-10T01:52:35.587Z', timeDroppedOff: '2022-06-10T02:00:34.696Z', timeCancelled: null, …}
ConsoleLogger.ts:115 [DEBUG] 02:04.895 DataStore - Attempting mutation with authMode: API_KEY
ConsoleLogger.ts:115 [DEBUG] 02:04.896 Util -  attempt #1 with this vars: ["Task","Update","{\"timeRiderHome\":\"2022-06-10T02:02:04.836Z\",\"status\":\"COMPLETED\",\"id\":\"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0\",\"_version\":318,\"_lastChangedAt\":1654826464061,\"_deleted\":null}","{}",null,null,{"data":"{\"timeRiderHome\":\"2022-06-10T02:02:04.836Z\",\"status\":\"COMPLETED\",\"id\":\"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0\",\"_version\":318,\"_lastChangedAt\":1654826464061,\"_deleted\":null}","modelId":"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0","model":"Task","operation":"Update","condition":"{}","id":"01G55M7Q5TB189H8P2QFKV0F38"}]
ConsoleLogger.ts:125 [DEBUG] 02:04.896 RestClient - POST https://xpbl3vag25afng2n6ishxbo74y.appsync-api.eu-west-1.amazonaws.com/graphql
ConsoleLogger.ts:115 [DEBUG] 02:05.204 AWSAppSyncRealTimeProvider - subscription message from AWS AppSync RealTime: {"id":"55de9349-e5e3-4391-9ff0-daa8235c61a2","type":"data","payload":{"data":{"onUpdateTask":{"id":"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0","status":"COMPLETED","timePickedUp":"2022-06-10T01:52:35.587Z","timeDroppedOff":"2022-06-10T02:00:34.696Z","timeCancelled":null,"timeRejected":null,"timeRiderHome":"2022-06-10T02:02:04.836Z","createdAt":"2022-06-09T18:38:06.466Z","updatedAt":"2022-06-10T02:02:04.971Z","_version":319,"_lastChangedAt":1654826525012,"_deleted":null}}}}
ConsoleLogger.ts:118 [DEBUG] 02:05.204 AWSAppSyncRealTimeProvider {id: '55de9349-e5e3-4391-9ff0-daa8235c61a2', observer: SubscriptionObserver, query: 'subscription operation {\n  onUpdateTask {\n    id\n …  _version\n    _lastChangedAt\n    _deleted\n  }\n}\n', variables: {…}}
ConsoleLogger.ts:115 [DEBUG] 02:06.917 DataStore - Mutation sent successfully with authMode: API_KEY
App.js:126 Model {id: '38b35b73-2b4a-406a-bcf0-de0bc56ee8d0', status: 'COMPLETED', timePickedUp: '2022-06-10T01:52:35.587Z', timeDroppedOff: '2022-06-10T02:00:34.696Z', timeCancelled: null, …}
ConsoleLogger.ts:125 [DEBUG] 02:09.126 DataStore - params ready {predicate: {…}, pagination: {…}, modelConstructor: ƒ}
App.js:126 Model {id: '38b35b73-2b4a-406a-bcf0-de0bc56ee8d0', status: 'DROPPED_OFF', timePickedUp: '2022-06-10T01:52:35.587Z', timeDroppedOff: '2022-06-10T02:00:34.696Z', timeCancelled: null, …}
ConsoleLogger.ts:115 [DEBUG] 02:09.162 DataStore - Attempting mutation with authMode: API_KEY
ConsoleLogger.ts:115 [DEBUG] 02:09.162 Util -  attempt #1 with this vars: ["Task","Update","{\"timeRiderHome\":null,\"status\":\"DROPPED_OFF\",\"id\":\"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0\",\"_version\":319,\"_lastChangedAt\":1654826525012,\"_deleted\":null}","{}",null,null,{"data":"{\"timeRiderHome\":null,\"status\":\"DROPPED_OFF\",\"id\":\"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0\",\"_version\":319,\"_lastChangedAt\":1654826525012,\"_deleted\":null}","modelId":"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0","model":"Task","operation":"Update","condition":"{}","id":"01G55M7Q5TB189H8P2QFKV0F39"}]
ConsoleLogger.ts:125 [DEBUG] 02:09.163 RestClient - POST https://xpbl3vag25afng2n6ishxbo74y.appsync-api.eu-west-1.amazonaws.com/graphql
ConsoleLogger.ts:115 [DEBUG] 02:09.494 AWSAppSyncRealTimeProvider - subscription message from AWS AppSync RealTime: {"id":"55de9349-e5e3-4391-9ff0-daa8235c61a2","type":"data","payload":{"data":{"onUpdateTask":{"id":"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0","status":"DROPPED_OFF","timePickedUp":"2022-06-10T01:52:35.587Z","timeDroppedOff":"2022-06-10T02:00:34.696Z","timeCancelled":null,"timeRejected":null,"timeRiderHome":null,"createdAt":"2022-06-09T18:38:06.466Z","updatedAt":"2022-06-10T02:02:09.217Z","_version":320,"_lastChangedAt":1654826529232,"_deleted":null}}}}
ConsoleLogger.ts:118 [DEBUG] 02:09.494 AWSAppSyncRealTimeProvider {id: '55de9349-e5e3-4391-9ff0-daa8235c61a2', observer: SubscriptionObserver, query: 'subscription operation {\n  onUpdateTask {\n    id\n …  _version\n    _lastChangedAt\n    _deleted\n  }\n}\n', variables: {…}}
ConsoleLogger.ts:125 [DEBUG] 02:09.694 DataStore - params ready {predicate: {…}, pagination: {…}, modelConstructor: ƒ}
App.js:126 Model {id: '38b35b73-2b4a-406a-bcf0-de0bc56ee8d0', status: 'COMPLETED', timePickedUp: '2022-06-10T01:52:35.587Z', timeDroppedOff: '2022-06-10T02:00:34.696Z', timeCancelled: null, …}
ConsoleLogger.ts:115 [DEBUG] 02:10.214 AWSAppSyncRealTimeProvider - subscription message from AWS AppSync RealTime: {"type":"ka"}
ConsoleLogger.ts:118 [DEBUG] 02:10.214 AWSAppSyncRealTimeProvider {id: '', observer: null, query: '', variables: {…}}
ConsoleLogger.ts:115 [DEBUG] 02:11.206 DataStore - Mutation sent successfully with authMode: API_KEY
ConsoleLogger.ts:115 [DEBUG] 02:11.227 DataStore - Attempting mutation with authMode: API_KEY
ConsoleLogger.ts:115 [DEBUG] 02:11.227 Util -  attempt #1 with this vars: ["Task","Update","{\"timeRiderHome\":\"2022-06-10T02:02:09.692Z\",\"status\":\"COMPLETED\",\"id\":\"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0\",\"_version\":319,\"_lastChangedAt\":1654826525012,\"_deleted\":null}","{}",null,null,{"data":"{\"timeRiderHome\":\"2022-06-10T02:02:09.692Z\",\"status\":\"COMPLETED\",\"id\":\"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0\",\"_version\":319,\"_lastChangedAt\":1654826525012,\"_deleted\":null}","modelId":"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0","model":"Task","operation":"Update","condition":"{}","id":"01G55M7Q5TB189H8P2QFKV0F3A"}]
ConsoleLogger.ts:125 [DEBUG] 02:11.228 RestClient - POST https://xpbl3vag25afng2n6ishxbo74y.appsync-api.eu-west-1.amazonaws.com/graphql
ConsoleLogger.ts:115 [DEBUG] 02:11.535 AWSAppSyncRealTimeProvider - subscription message from AWS AppSync RealTime: {"id":"55de9349-e5e3-4391-9ff0-daa8235c61a2","type":"data","payload":{"data":{"onUpdateTask":{"id":"38b35b73-2b4a-406a-bcf0-de0bc56ee8d0","status":"DROPPED_OFF","timePickedUp":"2022-06-10T01:52:35.587Z","timeDroppedOff":"2022-06-10T02:00:34.696Z","timeCancelled":null,"timeRejected":null,"timeRiderHome":"2022-06-10T02:02:09.692Z","createdAt":"2022-06-09T18:38:06.466Z","updatedAt":"2022-06-10T02:02:09.217Z","_version":321,"_lastChangedAt":1654826531350,"_deleted":null}}}}
ConsoleLogger.ts:118 [DEBUG] 02:11.535 AWSAppSyncRealTimeProvider {id: '55de9349-e5e3-4391-9ff0-daa8235c61a2', observer: SubscriptionObserver, query: 'subscription operation {\n  onUpdateTask {\n    id\n …  _version\n    _lastChangedAt\n    _deleted\n  }\n}\n', variables: {…}}
ConsoleLogger.ts:115 [DEBUG] 02:13.248 DataStore - Mutation sent successfully with authMode: API_KEY
App.js:126 Model {id: '38b35b73-2b4a-406a-bcf0-de0bc56ee8d0', status: 'DROPPED_OFF', timePickedUp: '2022-06-10T01:52:35.587Z', timeDroppedOff: '2022-06-10T02:00:34.696Z', timeCancelled: null, …}

aws-exports.js

const awsmobile = {
    "aws_project_region": "eu-west-1",
    "aws_appsync_graphqlEndpoint": "https://xpbl3vag25afng2n6ishxbo74y.appsync-api.eu-west-1.amazonaws.com/graphql",
    "aws_appsync_region": "eu-west-1",
    "aws_appsync_authenticationType": "API_KEY",
    "aws_appsync_apiKey": "da2-vs6oo7xssvdn7lnqbpene4fmla",
    "aws_cognito_identity_pool_id": "eu-west-1:7bbed19f-d205-4101-9829-ebfa833ec06d",
    "aws_cognito_region": "eu-west-1",
    "aws_user_pools_id": "eu-west-1_VD0AQtRSn",
    "aws_user_pools_web_client_id": "63l0hbdlt41u10th59cnfom53c",
    "oauth": {},
    "aws_cognito_username_attributes": [],
    "aws_cognito_social_providers": [],
    "aws_cognito_signup_attributes": [
        "EMAIL"
    ],
    "aws_cognito_mfa_configuration": "OFF",
    "aws_cognito_mfa_types": [
        "SMS"
    ],
    "aws_cognito_password_protection_settings": {
        "passwordPolicyMinLength": 8,
        "passwordPolicyCharacters": []
    },
    "aws_cognito_verification_mechanisms": [
        "EMAIL"
    ]
};


export default awsmobile;

Manual configuration

No response

Additional configuration

No response

Mobile Device

No response

Mobile Operating System

No response

Mobile Browser

No response

Mobile Browser Version

No response

Additional information and screenshots

A video demonstration (sorry for quality, the webm looked much better but github won’t attach it):

https://user-images.githubusercontent.com/32309223/172974634-359942aa-2387-45a1-8f2d-88797ef15353.mp4

An example of where the status field mismatches what was sent to the API (timeRiderHome, timeDroppedOff and timePickedUp all being set means the status should be COMPLETED). This doesn’t always happen, but does often.

Screenshot from 2022-06-10 02-53-11

The entry in dynamoDB where the status doesn’t match:

About this issue

Original URL
State: closed
Created 2 years ago
Comments: 20 (7 by maintainers)

Most upvoted comments

@duckbytes - We have a plan to improve the experience with Auto Merge but it is still work in progress due to the underlying complexity of the fix. Our recommendation in general, is to use Optimistic Concurrency. I understand that you’re facing bug #11708 and we’ll investigate that in parallel to unblock you from continuing to use optimistic concurrency.

arundna on Sep 8, 2023

Are there downsides or considerations to take when using optimistic concurrency until this is fixed?

I found documentation here about writing a conflict resolution function https://docs.amplify.aws/lib/datastore/conflict/q/platform/js/#custom-configuration

Is there any recommended logic to use there until we can go back to using auto-merge?

@duckbytes Not sure if this helps, but switching to optimistic concurrency broke our auto-increment logic where we issue an empty GraphQL update to atomically increment the Counter model _version attribute. To make it work with optimistic concurrency, we would have to query the record first for the latest _version, then make an update with the latest _version value known to client. This could fail if there are many concurrent updates on the same record as it is prone to race conditions.

Optimistic concurrency didn’t resolve the DataStore issue for us, so we simply switched back to auto-merge.

dmitrytenera on Sep 12, 2022

Thanks @undefobj switching to optimistic concurrency looks to have fixed it.

duckbytes on Jun 14, 2022

@duckbytes thank you for this. We have determined the issue is due to a comparison problem between changed fields on the clients and the network response when using AutoMerge. We have a plan to solve this but it will take some care on our side for this scenario with testing. In the meantime if you are blocked on this particular behavior we would suggest switching your Conflict Resolution strategy to Optimistic Concurrency rather than AutoMerge if possible.

undefobj on Jun 14, 2022