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I've created a lambda function so that I can use it for validation purposes and then proxy the request to the service layer. Then the service layer response contains a binary blob(PDF), which goes through the lambda function then the API gateway finally would reach the client.

The first problem we ran into was the PDF got transformed or corrupted, just returned blank PDF. And then I found this post which did not make any sense to me at first. Until I saw this aws doc. It turns out it's required to encode the binary data into base64 and then put the indictor 'isBase64Encoded' to true. The gateway eventually converts the response back to the binary blob.

TBH, I am new to aws and I don't really understand why this is the way..what's wrong of passing through the original binary blob, why those conversion steps are necessary?

Here are list of things i had to do

  1. Configured / as a Binary Media Type on gateway. (I tried to use application/pdf, but did not work?)
  2. Make sure the response body from the service layer not transformed into string (I am using request, and by default it gives me string). I send encoding: null along with the request
  3. When i get the Buffer data from the service layer, i use Buffer to convert response body into base64 encoding.
  4. In the lambda output, I set isBase64Encoded to true

Finally, get the unaltered PDF...

I am wondering if someone can confirm i am doing in an expected way? Or maybe if there is a better way?

Also, when we set binary support media type to /, doesn't this mean it accepts all media types? But i only want the PDF to be supported.

Isaac Guan
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1 Answers1

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This doc (https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-payload-encodings.html) should be able to answer your question. And there are two things you need to note:

Youwithouto
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