Using DataMapper to Get Item From DynamoDB Throws Runtime Error

Question

I am using Typescript to implement a Lambda, that connects to a Dynamo db table in the same region. When I try to scan or get items from the table, I'm getting the following errors.

For Scan:

2023-01-04T20:02:56.603Z 1ef44a6b-8b4f-51c5-bd10-164456efc703 ERROR Invoke Error { "errorType": "TypeError", "errorMessage": "this.client.scan(...).promise is not a function", "stack": [ "TypeError: this.client.scan(...).promise is not a function", " at ScanPaginator.getNext (/var/task/node_modules/@aws/dynamodb-query-iterator/build/ScanPaginator.js:17:18)", " at /var/task/node_modules/@aws/dynamodb-query-iterator/build/DynamoDbPaginator.js:60:26" ] }

For Get:

{ "errorType": "Runtime.UnhandledPromiseRejection", "errorMessage": "TypeError: _b.map is not a function", "reason": { "errorType": "TypeError", "errorMessage": "_b.map is not a function", "stack": [ "TypeError: _b.map is not a function", " at /var/task/node_modules/@aws-sdk/middleware-user-agent/dist-cjs/user-agent-middleware.js:14:151", " at async /var/task/node_modules/@aws-sdk/middleware-logger/dist-cjs/loggerMiddleware.js:5:22" ] }, "promise": {}, "stack": [ "Runtime.UnhandledPromiseRejection: TypeError: _b.map is not a function", " at process. (file:///var/runtime/index.mjs:1194:17)", " at process.emit (node:events:513:28)", " at emit (node:internal/process/promises:149:20)", " at processPromiseRejections (node:internal/process/promises:283:27)", " at process.processTicksAndRejections (node:internal/process/task_queues:96:32)" ] }

I'm using the DataMapper from @aws/dynamodb-data-mapper along with @aws-sdk/client-dynamodb in my Handler code to read from the Dynamo DB table.

Below is my DTO code:

@table("Configs")
export class Configs {
    @hashKey()
    configId!: string;

    @attribute()
    groupName!: string
}

Below is the Lambda Handler code:

import {SQSEvent} from "aws-lambda";
import {DynamoDB} from "@aws-sdk/client-dynamodb"
import {DataMapper} from "@aws/dynamodb-data-mapper";
import {Configs} from "./models/Configs";

const client = new DynamoDB({region: "us-east-1"});
const mapper = new DataMapper({client});

export const handler = async (sqsEvent: SQSEvent) => {
    console.log(`Event: ${JSON.stringify(sqsEvent, null, 2)}`);
    for (let record of sqsEvent.Records) {
        let messageBody = record.body;
        console.log("MessageBody: " + messageBody);
    }
    const config = new Configs();

    for await (const item of mapper.scan(Configs)) {
        console.log('scan result', item);
    }

    console.log("done scanning");

    mapper.get(Object.assign(new Configs(), {id: 'MY_ID'}))
        .then(myItem => {
            console.log('MyItem from db: ', myItem);
        })
        .catch(err => {
            console.log("Not found");
        })
};

Below is my tsconfig.json

{
  "compilerOptions": {
    "experimentalDecorators": true,
    "target": "es2020",
    "strict": true,
    "preserveConstEnums": true,
    "outDir": "./dist/lib",
    "module": "CommonJS",
    "declaration": true,
    "declarationDir": "./dist/types",
    "sourceMap": false,
    "moduleResolution":"node",
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "isolatedModules": true,
    "emitDecoratorMetadata": true,
    "typeRoots": [
      "./node_modules/@types"
    ]
  },
  "exclude": [
    "./node_modules", "**/*.test.ts"]
}

What am I doing wrong here? I referred to the documentation here on DataMapper https://awslabs.github.io/dynamodb-data-mapper-js/packages/dynamodb-data-mapper/ and still couldn't figure out what I'm doing wrong. Would greatly appreciate any help. Thanks in advance.

Leeroy Hannigan · Accepted Answer · 2023-01-04 20:28:26Z

1

I believe this is because you are importing AWS SDK JS V3 for DynamoDB:

import {DynamoDB} from "@aws-sdk/client-dynamodb"

Whereas the dynamodb-data-mapper is built for SDK V2. You should install a V2 client for DynamoDB:

import DynamoDB = require('aws-sdk/clients/dynamodb');

answered Jan 4, 2023 at 20:28

Leeroy Hannigan

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