How to pass a file to AWS Textract using serverless.js, where the file is in base64 format.

serverless-handler-with-textract.js

/*
This is a example serverless.js handler where we pass the 
document we want to analyze as a base64 string (in a json payload)
and returns the result from textract.

Request:
  {
    "document": "/9j/4AAQS......."
  }
  
Response:
  {
    "analyzeData": {
      "DocumentMetadata": {
        "Pages": 1
      },
      ...
  }
*/

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

AWS.config.update({
  accessKeyId: "XXXXX",
  secretAccessKey: "XXXXX",
  region: "eu-west-1",
});

const getImageText = async (event, context) => {
  const { document } = JSON.parse(event.body);

  const params = {
    Document: {
      Bytes: new Buffer(document, 'base64'),
    },
    FeatureTypes: [
      "TABLES",
    ]
  };

  let analyzeData = null;
  try {
    const textract = new AWS.Textract();
    analyzeData = await textract.analyzeDocument(document);
  } catch (err) {
    return {
      statusCode: err.statusCode,
      body: JSON.stringify({
        message: "Error passing data to analyze",
        code: err.code,
      })
    };
  }

  return {
    statusCode: 200,
    body: JSON.stringify({
      analyzeData,
    })
  }
};

module.exports = {
  getImageText,
}