Dynamodb batchWrite doesn't work in Lambda

Question

I tried to insert one data into Dynamodb using batchWrite though, it couldn't insert data. It just shows this message (but no error message).

Ensuring latest function changes are built...
Starting execution...
{"key1":"value1","key2":"value2","key3":"value3"}
Result:
null
Finished execution.

Then, cannot insert data. I tried to use put tho, it worked well. I'm using Lambda. This is the code.

const dynamodb = new AWS.DynamoDB.DocumentClient();
let tableName = "BlrSession-56pfbzohnvdqpac6asb627z2wu-dev";

// const AWS = require("aws-sdk/global");

exports.handler = (event, context, callback) => {
  // The event parameter is the input to your lambda function
  console.log(JSON.stringify(event));
  let games = [];
  let documentClient = new AWS.DynamoDB.DocumentClient();

  // lambda.forEach((item) => {
  games.push({
    PutRequest: {
      Item: {
        id: Math.random().toString(36).substring(2) + Date.now().toString(36),
      },
    },
  });
  // });

  let params = {
    RequestItems: {
      tableName: games,
    },
  };

  documentClient.batchWrite(params, function (err, data) {
    if (err) {
      callback(err);
    } else {
      callback(null, data);
    }
  });
};

How you confirm that it cannot insert data.?

hoangdv
– hoangdv

2021-04-04 03:48:33 +00:00
Commented Apr 4, 2021 at 3:48 — hoangdv
– hoangdv, Commented Apr 4, 2021 at 3:48
I confirmed it by checking Dynamodb table.

uekyo
– uekyo

2021-04-04 06:34:11 +00:00
Commented Apr 4, 2021 at 6:34 — uekyo
– uekyo, Commented Apr 4, 2021 at 6:34

Balu Vyamajala · Accepted Answer · 2021-04-04 22:09:29Z

2

There is just one issue with code. tableName used as Key in params is not being replaced with actual table name, we can use variable name as key by wrapping it around [tableName]

  let params = {
    RequestItems: {
      [tableName]: games,
    },
  };

This is full lambda

const AWS = require("aws-sdk");
AWS.config.update({ region: "us-east-1" });
const dynamodb = new AWS.DynamoDB.DocumentClient();
let documentClient = new AWS.DynamoDB.DocumentClient();
let tableName = "test";

exports.handler = (event, context, callback) => {
  let games = [];
  games.push({
    PutRequest: {
      Item: {
        id: Math.random().toString(36).substring(2) + Date.now().toString(36),
      },
    },
  });

  let params = {
    RequestItems: {
      [tableName]: games,
    },
  };
  console.log('params',params);
  documentClient.batchWrite(params, function (err, data) {
    if (err) {
      console.log('err', err);
      callback(err);
    } else {
      console.log('data', data);
      callback(null, data);
    }
  });
};

edited Apr 4, 2021 at 22:09

answered Apr 3, 2021 at 23:10

Balu Vyamajala

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5 Comments

uekyo Over a year ago

Thanks, Balu. I tried it but the result was the same. mmm

Balu Vyamajala Over a year ago

i tested your code, except this , everything else is good. may be some permissions are missing?

uekyo Over a year ago

I posted the permission on the above. Does it seem to be something wrong?

Balu Vyamajala Over a year ago

@uekyo policy looks ok. i pasted full lambda code i tested.

uekyo Over a year ago

OMG, I did it! Thanks, bruh!

uekyo · Accepted Answer · 2021-04-04 21:42:26Z

This is the permission when it doesn't work to use batchWrite

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Action": [
                "dynamodb:Put*",
                "dynamodb:Create*",
                "dynamodb:BatchWriteItem",
                "dynamodb:Get*",
                "dynamodb:BatchGetItem",
                "dynamodb:List*",
                "dynamodb:Describe*",
                "dynamodb:Scan",
                "dynamodb:Query",
                "dynamodb:Update*",
                "dynamodb:RestoreTable*",
                "dynamodb:Delete*"
            ],
            "Resource": [
                "arn:aws:dynamodb:us-west-2:613917858805:table/BlrSession-56pfbzohnvdqpac6asb627z2wu-dev",
                "arn:aws:dynamodb:us-west-2:613917858805:table/BlrSession-56pfbzohnvdqpac6asb627z2wu-dev/index/*"
            ],
            "Effect": "Allow"
        },
        {
            "Action": [
                "dynamodb:Put*",
                "dynamodb:Create*",
                "dynamodb:BatchWriteItem",
                "dynamodb:Get*",
                "dynamodb:BatchGetItem",
                "dynamodb:List*",
                "dynamodb:Describe*",
                "dynamodb:Scan",
                "dynamodb:Query",
                "dynamodb:Update*",
                "dynamodb:RestoreTable*",
                "dynamodb:Delete*"
            ],
            "Resource": [
                "arn:aws:dynamodb:us-west-2:613917858805:table/BlrMeetup-56pfbzohnvdqpac6asb627z2wu-dev",
                "arn:aws:dynamodb:us-west-2:613917858805:table/BlrMeetup-56pfbzohnvdqpac6asb627z2wu-dev/index/*"
            ],
            "Effect": "Allow"
        }
    ]
}```

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