How to write file in memory or to file in Lambda aws?

Question

I want to use lambda to get database from dynamodb and generate compute data to cvs file.

Then attach this file with email send to customer.

Step

Get data from dynamodb. (I know how to do it .)
Write to file .CSV ( need help).

Because lambda doesn't have persisted data. How to write to file

Attach .CSV to email and send to customer. ( need help)

Community · Accepted Answer · 2017-05-23 12:01:43Z

3

Do you have an existing setup for sending email? You don't necessarily need to save a file to create a file attachment when sending an email.

simply ignore the fs.readFile statement in the response below

Sending mails with attachment via NodeJS

edited May 23, 2017 at 12:01

CommunityBot

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answered Mar 8, 2015 at 22:27

Matthew Kime

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AdrieanKhisbe · Accepted Answer · 2017-02-14 09:40:40Z

2

If you're writing a CSV, you'll probably need to stream the data to S3. Lambda has a pretty good example here for streaming image data from a buffer. Obviously you're not using an image but the concept is about the same.

get your data from db
format it how you need it. I'd recommend looking into streams with something like csv-write-stream.
stream data to s3 with something like s3-streaming-upload or the aws-sdk.
as part of the response from the SDK, you'd get the location of your file.
i'd use mandrill (https://mandrillapp.com/api/docs/messages.html) because it's ~~free~~, easy, and awesome. you can set the attachment content as base64. Yours might look something like this:
```
"attachments": [
  {
    "type": "text/csv",
    "name": "myfile.csv",
    "content": new Buffer( myCsvContent ).toString('base64')
   }
]
```

I haven't tested this but did something similar recently and this general approach should work for you.

edited Feb 14, 2017 at 9:40

AdrieanKhisbe

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answered Mar 8, 2015 at 22:38

imjared

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1 Comment

imjared Over a year ago

I was thinking on this some more and realized you didn't explicitly say you need to save the CSV. If you don't, then definitely ignore the s3 steps since it just complicates what you're trying to do. You can just stream to a buffer then base64 encode that and attach it to an email.

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