How do I create and send csv using aws lambda and nodejs? - javascript

I am writing a lambda function that fetches data from DynamoDB and stores it in an array. Now I want to create a CSV file from this array and return it. (preferably directly from the lambda function, rather than uploading it to s3 and then sharing the link). Any idea, how to do this?
My code until now -
import AWS from "aws-sdk";
import createError from "http-errors";
import commonMiddleware from "../lib/commonMiddleware";
const dynamodb = new AWS.DynamoDB.DocumentClient();
async function getFile(event, context) {
const { id: someId } = event.pathParameters;
let data;
const params = {
TableName: process.env.TABLE_NAME,
IndexName: "GSIsomeId",
KeyConditionExpression: "someId = :someId",
ExpressionAttributeValues: {
":someId": someId,
},
};
try {
const result = await dynamodb.query(params).promise();
data = result.Items;
} catch (error) {
console.error(error);
throw new createError.InternalServerError(error);
}
// data is array of objects which I can change to 2d array using Object.values()
// I want to create and return a CSV from this array
return {
statusCode: 200,
body: JSON.stringify(data),
};
}
export const handler = commonMiddleware(getFile);

Once you generated the csv using any of the approaches mentioned here Convert JSON array to CSV in Node
I guess you can try sending back the byte array of the file.

Related

Problems accessing data from a GraphQL query in Javascript with Svelte

Below I have my working function using a normal REST response that I want to try to convert into a GraphQL version, it fetches a JSON doc from my Phoenix Server and stores the object values from the JSON doc into an object. The problem is, here I can use await and then assign the new object values from the object within the JSON document, but using GraphQL I cannot access this data to assign it because there is no await function as its just a Query. (From what I know)
async function updatePageWithNewCompany(company){
const res = await fetch(`http://localhost:4000/${company}`);
profile = await res.json();
profile = profile.companyProfile
DashboardStore.update(currentData => {
return {
id: profile.id,
companyName: `${profile.company_name}`,
averageLength: profile.average_length,
}
})
Ultimately I am asking if there is a way to access and assign data from a GraphQL query in JavaScript so I can manipulate it before displaying it in my frontend Svelte app.
Example of current GraphQL query:
import { gql } from '#apollo/client'
import { client } from './apollo';
import { query, setClient } from "svelte-apollo";
setClient(client)
const GET_COMPANY = gql`
query{
companyProfile(){
companyName
averageLength
}
}
`;
const response = query(GET_COMPANY)
...
svelte-apollo queries return
a svelte store of promises that resolve as values come in
as stated in the example query displayed in the documentation.
As such, you can exploit that format directly in the script section. Here is an example:
...
async function getCompany() {
const companyStore = query(GET_COMPANY)
const company = (await $companyStore).data.companyProfile
return company // format will be an object with keys { companyName, averageLength } according to your query
}
...
On a side-note I would recommend always getting the id of objects in your GraphQL queries as it is usually the key used internally by the Apollo client to manage its cache (unless explicitly stated otherwise).
I have found a working solution with the help of #Thomas-Hennes
import { client } from '../apollo.js';
import { onMount } from "svelte";
import { gql } from '#apollo/client'
export const COMPANY_LIST = gql`
query {
listCompanies{
companyName
}
}
`;
async function listCompanies() {
await client.query({query: COMPANY_LIST})
.then(res => {
companyList.update( currentData =>
[...res.data.listCompanies.companyName])})
};
onMount(() =>{
listCompanies()
})
await didn't like being assigned to a variable or having its data manipulated so i used it as a promise instead and manipulated the response.
The below link helped me find the final piece of the puzzle.
https://docs.realm.io/sync/graphql-web-access/using-the-graphql-client

Calling a function that contains a promise from another function

I am trying to learn how to use promises in NodeJs and I am using the AWS-SDK library to access an S3 object. My goal is to call the readFromS3() function from within the init() function and print out the contents of the file. However, I am not getting the results I want as shown below by the first console.log statement inside the init(). I understand that the promise is not complete and wanted your suggestions on how I can block execution until the news object is NOT null ??
const AWS = require('aws-sdk');
const S3 = new AWS.S3({});
const CONFIG = {
init() {
const news = CONFIG.readFromS3();
console.log('These are the file contents ' + JSON.stringify(news));
console.log('THIS IS THE END. This should only print after news have been read from S3');
},
readFromS3() {
// set parameters for reading S3 files
const options = {
Bucket: 'my-bucket',
Key: 'myFile.txt'
};
// create a promise to read from S3
const readS3Promise = S3.getObject(options).promise();
// start reading from s3
readS3Promise
.then(function(data) {
return JSON.parse(data.Body);
});
})
.catch(function(error) {
console.log('ERROR: Cannot read from S3');
throw error;
});
}
};
CONFIG.init();
However, My output currently is like this unfortunately:
These are the SPECS undefined
THIS IS THE END. This should only print after news have been read from S3
{... // JSON data from S3 printed out
You need to return your promise from read method and await that call inside init function so you can get output. something like this
const AWS = require('aws-sdk');
const S3 = new AWS.S3({});
const CONFIG = {
async init() {
const news = await CONFIG.readFromS3();
console.log('These are the file contents ' + JSON.stringify(news));
console.log('THIS IS THE END. This should only print after news have been read from S3');
},
readFromS3() {
// set parameters for reading S3 files
const options = {
Bucket: 'my-bucket',
Key: 'myFile.txt'
};
// create a promise to read from S3
const readS3Promise = S3.getObject(options).promise();
// start reading from s3
return readS3Promise
.then(function(data) {
return JSON.parse(data.Body);
});
})
.catch(function(error) {
console.log('ERROR: Cannot read from S3');
throw error;
});
}
};
CONFIG.init();

Cloudinary Signed Uploads with Widget

Documentation is extremely frustrating.
I'm using the upload widget to try to allow users to upload multiple pictures for their profile. I can't use unsigned uploads because of the potential for abuse.
I would much rather upload the file through the upload widget instead of through the server as it seems like it should be so simple
I've pieced together what I think should work but it is still saying: Upload preset must be whitelisted for unsigned uploads
Server:
// grab a current UNIX timestamp
const millisecondsToSeconds = 1000;
const timestamp = Math.round(Date.now() / millisecondsToSeconds);
// generate the signature using the current timestmap and any other desired Cloudinary params
const signature = cloudinaryV2.utils.api_sign_request({ timestamp }, CLOUDINARY_SECRET_KEY);
// craft a signature payload to send to the client (timestamp and signature required)
return signature;
also tried
return {
signature,
timestamp,
};
also tried
const signature = cloudinaryV2.utils.api_sign_request(
data.params_to_sign,
CLOUDINARY_SECRET_KEY,
);
Client:
const generateSignature = async (callback: Function, params_to_sign: object): Promise<void> => {
try {
const signature = await generateSignatureCF({ slug: 'xxxx' });
// also tried { slug: 'xxxx', params_to_sign }
callback(signature);
} catch (err) {
console.log(err);
}
};
cloudinary.openUploadWidget(
{
cloudName: 'xxx',
uploadPreset: 'xxxx',
sources: ['local', 'url', 'facebook', 'dropbox', 'google_photos'],
folder: 'xxxx',
apiKey: ENV.CLOUDINARY_PUBLIC_KEY,
uploadSignature: generateSignature,
},
function(error, result) {
console.log(error);
},
);
Let's all take a moment to point out how horrible Cloudinary's documentation is. It's easily the worst i've ever seen. Nightmare fuel.
Now that i've got that off my chest... I really needed to be able to do this and I spent way too long banging my head against walls for what should be extremely simple. Here it is...
Server (Node.js)
You'll need an endpoint that returns a signature-timestamp pair to the frontend:
import cloudinary from 'cloudinary'
export async function createImageUpload() {
const timestamp = new Date().getTime()
const signature = await cloudinary.utils.api_sign_request(
{
timestamp,
},
process.env.CLOUDINARY_SECRET
)
return { timestamp, signature }
}
Client (Browser)
The client makes a request to the server for a signature-timestamp pair and then uses that to upload a file. The file used in the example should come from an <input type='file'/> change event etc.
const CLOUD_NAME = process.env.CLOUDINARY_CLOUD_NAME
const API_KEY = process.env.CLOUDINARY_API_KEY
async function uploadImage(file) {
const { signature, timestamp } = await api.post('/image-upload')
const form = new FormData()
form.append('file', file)
const res = await fetch(
`https://api.cloudinary.com/v1_1/${CLOUD_NAME}/image/upload?api_key=${API_KEY}&timestamp=${timestamp}&signature=${signature}`,
{
method: 'POST',
body: form,
}
)
const data = await res.json()
return data.secure_url
}
That's it. That's all it takes. If only Cloudinary had this in their docs.
Man. I hate my life. I finally figured it out. It literally took me beautifying the upload widget js to understand that the return of the function should be a string instead of an object even though the docs make it seem otherwise.
Here is how to implement a signed upload with a Firebase Cloud Function
import * as functions from 'firebase-functions';
import cloudinary from 'cloudinary';
const CLOUDINARY_SECRET_KEY = functions.config().cloudinary.key;
const cloudinaryV2 = cloudinary.v2;
module.exports.main = functions.https.onCall(async (data, context: CallableContext) => {
// Checking that the user is authenticated.
if (!context.auth) {
// Throwing an HttpsError so that the client gets the error details.
throw new functions.https.HttpsError(
'failed-precondition',
'The function must be called while authenticated.',
);
}
try {
return cloudinaryV2.utils.api_sign_request(data.params_to_sign, CLOUDINARY_SECRET_KEY);
} catch (error) {
throw new functions.https.HttpsError('failed-precondition', error.message);
}
});
// CLIENT
const uploadWidget = () => {
const generateSignature = async (callback: Function, params_to_sign: object): Promise<void> => {
try {
const signature = await generateImageUploadSignatureCF({ params_to_sign });
callback(signature.data);
} catch (err) {
console.log(err);
}
};
cloudinary.openUploadWidget(
{
cloudName: 'xxxxxx',
uploadSignature: generateSignature,
apiKey: ENV.CLOUDINARY_PUBLIC_KEY,
},
function(error, result) {
console.log(error);
},
);
};

Is there a way to get the previous version of a deleted s3 object with aws-sdk?

I have a S3 bucket with versioning enabled, configured to send notification events to Lambda. I need to process deleted objects from that bucket when the s3:ObjectRemoved:* event is received.
The event contains the versionId of the deleted object.
Is there a way to discover the versionId of the immediately previous version of the deleted object and fetch that version using the aws-sdk?
Or, alternatively, is there a way to get the deleted object using aws-sdk?
(I'm using the JavaScript aws-sdk)
It can be done with a 3-step process:
Get the list of versions with listObjectVersions
Get the wanted version from the list
Get the specific object,
passing VersionId as argument in getObject
const AWS = require('aws-sdk');
const s3 = new AWS.S3();
async function getDeletedObject (event, context) {
let params = {
Bucket: 'my-bucket',
Prefix: 'my-file'
};
try {
const previousVersion = await s3.listObjectVersions(params)
.promise()
.then(result => {
const versions = result.Versions;
// get previous versionId
return versions[0].VersionId;
});
params = {
Bucket: 'my-bucket',
Key: 'my-file',
VersionId: previousVersion
};
const deletedObject = await s3.getObject(params)
.promise()
.then(response => response.Body.toString('utf8'));
return deletedObject;
}
catch (error) {
console.log(error);
return;
}
}
Getting the below error with the solution mentioned by #andreswebs
IMG
UnhandledPromiseRejectionWarning: MethodNotAllowed: The specified method is not allowed against this resource.

How to get response from S3 getObject in Node.js?

In a Node.js project I am attempting to get data back from S3.
When I use getSignedURL, everything works:
aws.getSignedUrl('getObject', params, function(err, url){
console.log(url);
});
My params are:
var params = {
Bucket: "test-aws-imagery",
Key: "TILES/Level4/A3_B3_C2/A5_B67_C59_Tiles.par"
If I take the URL output to the console and paste it in a web browser, it downloads the file I need.
However, if I try to use getObject I get all sorts of odd behavior. I believe I am just using it incorrectly. This is what I've tried:
aws.getObject(params, function(err, data){
console.log(data);
console.log(err);
});
Outputs:
{
AcceptRanges: 'bytes',
LastModified: 'Wed, 06 Apr 2016 20:04:02 GMT',
ContentLength: '1602862',
ETag: '9826l1e5725fbd52l88ge3f5v0c123a4"',
ContentType: 'application/octet-stream',
Metadata: {},
Body: <Buffer 01 00 00 00 ... > }
null
So it appears that this is working properly. However, when I put a breakpoint on one of the console.logs, my IDE (NetBeans) throws an error and refuses to show the value of data. While this could just be the IDE, I decided to try other ways to use getObject.
aws.getObject(params).on('httpData', function(chunk){
console.log(chunk);
}).on('httpDone', function(data){
console.log(data);
});
This does not output anything. Putting a breakpoint in shows that the code never reaches either of the console.logs. I also tried:
aws.getObject(params).on('success', function(data){
console.log(data);
});
However, this also does not output anything and placing a breakpoint shows that the console.log is never reached.
What am I doing wrong?
#aws-sdk/client-s3 (2022 Update)
Since I wrote this answer in 2016, Amazon has released a new JavaScript SDK, #aws-sdk/client-s3. This new version improves on the original getObject() by returning a promise always instead of opting in via .promise() being chained to getObject(). In addition to that, response.Body is no longer a Buffer but, one of Readable|ReadableStream|Blob. This changes the handling of the response.Data a bit. This should be more performant since we can stream the data returned instead of holding all of the contents in memory, with the trade-off being that it is a bit more verbose to implement.
In the below example the response.Body data will be streamed into an array and then returned as a string. This is the equivalent example of my original answer. Alternatively, the response.Body could use stream.Readable.pipe() to an HTTP Response, a File or any other type of stream.Writeable for further usage, this would be the more performant way when getting large objects.
If you wanted to use a Buffer, like the original getObject() response, this can be done by wrapping responseDataChunks in a Buffer.concat() instead of using Array#join(), this would be useful when interacting with binary data. To note, since Array#join() returns a string, each Buffer instance in responseDataChunks will have Buffer.toString() called implicitly and the default encoding of utf8 will be used.
const { GetObjectCommand, S3Client } = require('#aws-sdk/client-s3')
const client = new S3Client() // Pass in opts to S3 if necessary
function getObject (Bucket, Key) {
return new Promise(async (resolve, reject) => {
const getObjectCommand = new GetObjectCommand({ Bucket, Key })
try {
const response = await client.send(getObjectCommand)
// Store all of data chunks returned from the response data stream
// into an array then use Array#join() to use the returned contents as a String
let responseDataChunks = []
// Handle an error while streaming the response body
response.Body.once('error', err => reject(err))
// Attach a 'data' listener to add the chunks of data to our array
// Each chunk is a Buffer instance
response.Body.on('data', chunk => responseDataChunks.push(chunk))
// Once the stream has no more data, join the chunks into a string and return the string
response.Body.once('end', () => resolve(responseDataChunks.join('')))
} catch (err) {
// Handle the error or throw
return reject(err)
}
})
}
Comments on using Readable.toArray()
Using Readable.toArray() instead of working with the stream events directly might be more convenient to use but, its worse performing. It works by reading all response data chunks into memory before moving on. Since this removes all benefits of streaming, this approach is discouraged per the Node.js docs.
As this method reads the entire stream into memory, it negates the benefits of streams. It's intended for interoperability and convenience, not as the primary way to consume streams. Documentation Link
#aws-sdk/client-s3 Documentation Links
GetObjectCommand
GetObjectCommandInput
GetObjectCommandOutput
aws-sdk (Original Answer)
When doing a getObject() from the S3 API, per the docs the contents of your file are located in the Body property, which you can see from your sample output. You should have code that looks something like the following
const aws = require('aws-sdk');
const s3 = new aws.S3(); // Pass in opts to S3 if necessary
var getParams = {
Bucket: 'abc', // your bucket name,
Key: 'abc.txt' // path to the object you're looking for
}
s3.getObject(getParams, function(err, data) {
// Handle any error and exit
if (err)
return err;
// No error happened
// Convert Body from a Buffer to a String
let objectData = data.Body.toString('utf-8'); // Use the encoding necessary
});
You may not need to create a new buffer from the data.Body object but if you need you can use the sample above to achieve that.
Based on the answer by #peteb, but using Promises and Async/Await:
const AWS = require('aws-sdk');
const s3 = new AWS.S3();
async function getObject (bucket, objectKey) {
try {
const params = {
Bucket: bucket,
Key: objectKey
}
const data = await s3.getObject(params).promise();
return data.Body.toString('utf-8');
} catch (e) {
throw new Error(`Could not retrieve file from S3: ${e.message}`)
}
}
// To retrieve you need to use `await getObject()` or `getObject().then()`
const myObject = await getObject('my-bucket', 'path/to/the/object.txt');
Updated (2022)
nodejs v17.5.0 added Readable.toArray. If this API is available in your node version. The code will be very short:
const buffer = Buffer.concat(
await (
await s3Client
.send(new GetObjectCommand({
Key: '<key>',
Bucket: '<bucket>',
}))
).Body.toArray()
)
If you are using Typescript, you are safe to cast the .Body part as Readable (the other types ReadableStream and Blob are only returned in browser environment. Moreover, in browser, Blob is only used in legacy fetch API when response.body is not supported)
(response.Body as Readable).toArray()
Note that: Readable.toArray is an experimental (yet handy) feature, use it with caution.
=============
Original answer
If you are using aws sdk v3, the sdk v3 returns nodejs Readable (precisely, IncomingMessage which extends Readable) instead of a Buffer.
Here is a Typescript version. Note that this is for node only, if you send the request from browser, check the longer answer in the blog post mentioned below.
import {GetObjectCommand, S3Client} from '#aws-sdk/client-s3'
import type {Readable} from 'stream'
const s3Client = new S3Client({
apiVersion: '2006-03-01',
region: 'us-west-2',
credentials: {
accessKeyId: '<access key>',
secretAccessKey: '<access secret>',
}
})
const response = await s3Client
.send(new GetObjectCommand({
Key: '<key>',
Bucket: '<bucket>',
}))
const stream = response.Body as Readable
return new Promise<Buffer>((resolve, reject) => {
const chunks: Buffer[] = []
stream.on('data', chunk => chunks.push(chunk))
stream.once('end', () => resolve(Buffer.concat(chunks)))
stream.once('error', reject)
})
// if readable.toArray() is support
// return Buffer.concat(await stream.toArray())
Why do we have to cast response.Body as Readable? The answer is too long. Interested readers can find more information on my blog post.
For someone looking for a NEST JS TYPESCRIPT version of the above:
/**
* to fetch a signed URL of a file
* #param key key of the file to be fetched
* #param bucket name of the bucket containing the file
*/
public getFileUrl(key: string, bucket?: string): Promise<string> {
var scopeBucket: string = bucket ? bucket : this.defaultBucket;
var params: any = {
Bucket: scopeBucket,
Key: key,
Expires: signatureTimeout // const value: 30
};
return this.account.getSignedUrlPromise(getSignedUrlObject, params);
}
/**
* to get the downloadable file buffer of the file
* #param key key of the file to be fetched
* #param bucket name of the bucket containing the file
*/
public async getFileBuffer(key: string, bucket?: string): Promise<Buffer> {
var scopeBucket: string = bucket ? bucket : this.defaultBucket;
var params: GetObjectRequest = {
Bucket: scopeBucket,
Key: key
};
var fileObject: GetObjectOutput = await this.account.getObject(params).promise();
return Buffer.from(fileObject.Body.toString());
}
/**
* to upload a file stream onto AWS S3
* #param stream file buffer to be uploaded
* #param key key of the file to be uploaded
* #param bucket name of the bucket
*/
public async saveFile(file: Buffer, key: string, bucket?: string): Promise<any> {
var scopeBucket: string = bucket ? bucket : this.defaultBucket;
var params: any = {
Body: file,
Bucket: scopeBucket,
Key: key,
ACL: 'private'
};
var uploaded: any = await this.account.upload(params).promise();
if (uploaded && uploaded.Location && uploaded.Bucket === scopeBucket && uploaded.Key === key)
return uploaded;
else {
throw new HttpException("Error occurred while uploading a file stream", HttpStatus.BAD_REQUEST);
}
}
Converting GetObjectOutput.Body to Promise<string> using node-fetch
In aws-sdk-js-v3 #aws-sdk/client-s3, GetObjectOutput.Body is a subclass of Readable in nodejs (specifically an instance of http.IncomingMessage) instead of a Buffer as it was in aws-sdk v2, so resp.Body.toString('utf-8') will give you the wrong result “[object Object]”. Instead, the easiest way to turn GetObjectOutput.Body into a Promise<string> is to construct a node-fetch Response, which takes a Readable subclass (or Buffer instance, or other types from the fetch spec) and has conversion methods .json(), .text(), .arrayBuffer(), and .blob().
This should also work in the other variants of aws-sdk and platforms (#aws-sdk v3 node Buffer, v3 browser Uint8Array subclass, v2 node Readable, v2 browser ReadableStream or Blob)
npm install node-fetch
import { Response } from 'node-fetch';
import * as s3 from '#aws-sdk/client-s3';
const client = new s3.S3Client({})
const s3Response = await client.send(new s3.GetObjectCommand({Bucket: '…', Key: '…'});
const response = new Response(s3Response.Body);
const obj = await response.json();
// or
const text = await response.text();
// or
const buffer = Buffer.from(await response.arrayBuffer());
// or
const blob = await response.blob();
Reference: GetObjectOutput.Body documentation, node-fetch Response documentation, node-fetch Body constructor source, minipass-fetch Body constructor source
Thanks to kennu comment in GetObjectCommand usability issue
Extremely similar answer to #ArianAcosta above. Except I'm using import (for Node 12.x and up), adding AWS config and sniffing for an image payload and applying base64 processing to the return.
// using v2.x of aws-sdk
import aws from 'aws-sdk'
aws.config.update({
accessKeyId: process.env.YOUR_AWS_ACCESS_KEY_ID,
secretAccessKey: process.env.YOUR_AWS_SECRET_ACCESS_KEY,
region: "us-east-1" // or whatever
})
const s3 = new aws.S3();
/**
* getS3Object()
*
* #param { string } bucket - the name of your bucket
* #param { string } objectKey - object you are trying to retrieve
* #returns { string } - data, formatted
*/
export async function getS3Object (bucket, objectKey) {
try {
const params = {
Bucket: bucket,
Key: objectKey
}
const data = await s3.getObject(params).promise();
// Check for image payload and formats appropriately
if( data.ContentType === 'image/jpeg' ) {
return data.Body.toString('base64');
} else {
return data.Body.toString('utf-8');
}
} catch (e) {
throw new Error(`Could not retrieve file from S3: ${e.message}`)
}
}
At first glance it doesn't look like you are doing anything wrong but you don't show all your code. The following worked for me when I was first checking out S3 and Node:
var AWS = require('aws-sdk');
if (typeof process.env.API_KEY == 'undefined') {
var config = require('./config.json');
for (var key in config) {
if (config.hasOwnProperty(key)) process.env[key] = config[key];
}
}
var s3 = new AWS.S3({accessKeyId: process.env.AWS_ID, secretAccessKey:process.env.AWS_KEY});
var objectPath = process.env.AWS_S3_FOLDER +'/test.xml';
s3.putObject({
Bucket: process.env.AWS_S3_BUCKET,
Key: objectPath,
Body: "<rss><data>hello Fred</data></rss>",
ACL:'public-read'
}, function(err, data){
if (err) console.log(err, err.stack); // an error occurred
else {
console.log(data); // successful response
s3.getObject({
Bucket: process.env.AWS_S3_BUCKET,
Key: objectPath
}, function(err, data){
console.log(data.Body.toString());
});
}
});
Alternatively you could use minio-js client library get-object.js
var Minio = require('minio')
var s3Client = new Minio({
endPoint: 's3.amazonaws.com',
accessKey: 'YOUR-ACCESSKEYID',
secretKey: 'YOUR-SECRETACCESSKEY'
})
var size = 0
// Get a full object.
s3Client.getObject('my-bucketname', 'my-objectname', function(e, dataStream) {
if (e) {
return console.log(e)
}
dataStream.on('data', function(chunk) {
size += chunk.length
})
dataStream.on('end', function() {
console.log("End. Total size = " + size)
})
dataStream.on('error', function(e) {
console.log(e)
})
})
Disclaimer: I work for Minio Its open source, S3 compatible object storage written in golang with client libraries available in Java, Python, Js, golang.
Just as an alternate solution:
As per this issue on the same subject, it seems like in October 2022, there is a way of handling the body returned from an S3 GetObject request. Assuming you are using AWS SDK V3, you can take advantage of the #aws-sdk/util-stream-node package in the official AWS SDK:
import { GetObjectCommand, S3Client } from '#aws-sdk/client-s3';
import { sdkStreamMixin } from '#aws-sdk/util-stream-node';
const s3Client = new S3Client({});
const { Body } = await s3Client.send(
new GetObjectCommand({
Bucket: 'your-bucket',
Key: 'your-key',
}),
);
// Throws error if Body is undefined
const body = await sdkStreamMixin(Body).transformToString();
You can also transform the body into a byte array or web stream using the .transformToByteArray() and .transformToWebStream() functions.
Keep in mind that the package says that you shouldn't be using it directly, but it seems to be the most straightforward way to handle the body from the request.
This was found in this reply that highlighted a PR that added this feature.
This is the async / await version
var getObjectAsync = async function(bucket,key) {
try {
const data = await s3
.getObject({ Bucket: bucket, Key: key })
.promise();
var contents = data.Body.toString('utf-8');
return contents;
} catch (err) {
console.log(err);
}
}
var getObject = async function(bucket,key) {
const contents = await getObjectAsync(bucket,key);
console.log(contents.length);
return contents;
}
getObject(bucket,key);
The Body.toString() method no longer works with the latest version of the s3 api. Use the following instead:
const { S3Client, GetObjectCommand } = require("#aws-sdk/client-s3");
const streamToString = (stream) =>
new Promise((resolve, reject) => {
const chunks = [];
stream.on("data", (chunk) => chunks.push(chunk));
stream.on("error", reject);
stream.on("end", () => resolve(Buffer.concat(chunks).toString("utf8")));
});
(async () => {
const region = "us-west-2";
const client = new S3Client({ region });
const command = new GetObjectCommand({
Bucket: "test-aws-sdk-js-1877",
Key: "readme.txt",
});
const { Body } = await client.send(command);
const bodyContents = await streamToString(Body);
console.log(bodyContents);
})();
Copy and pasted from here: https://github.com/aws/aws-sdk-js-v3/issues/1877#issuecomment-755387549
Not sure why this solution hasn't already been added as I think it is cleaner than the top answer.
Using express and AWS SDK v3:
public downloadFeedFile = (req: IFeedUrlRequest, res: Response) => {
const downloadParams: GetObjectCommandInput = parseS3Url(req.s3FileUrl.replace(/\s/g, ''));
logger.info("requesting S3 file " + JSON.stringify(downloadParams));
const run = async () => {
try {
const fileStream = await this.s3Client.send(new GetObjectCommand(downloadParams));
if (fileStream.Body instanceof Readable){
fileStream.Body.once('error', err => {
console.error("Error downloading s3 file")
console.error(err);
});
fileStream.Body.pipe(res);
}
} catch (err) {
logger.error("Error", err);
}
};
run();
};

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