Using Postman and AWS Lambdas to upload and download to S3 - amazon-web-services

Question

I have 2 lambda functions, to upload and downlaod a file from an S3 bucket. Im using Postman and configuring the POST and GET requests to have either a filename sent via json (GET Json payload: {"thefile" : "test_upload.txt"} ) and have set a form-data key of "thefile" and the value with the test file selected from my working directory on the computer.
The issue comes when sending the API requests via postman. Its giving me 'Internal Server Error'
The code for my lambdas is below:
**UPLOAD **
import json
import boto3
import os
def lambda_handler(event, context):
s3 = boto3.client('s3')
data = json.loads(event["body"])
file = data["thefile"]
print(file)
try:
s3.upload_file(file, os.environ['BUCKET_NAME'], file)
url = s3.generate_presigned_url(
ClientMethod='get_object',
Params={
'Bucket': os.environ['BUCKET_NAME'],
'Key': file
},
ExpiresIn=24 * 3600
)
print("Upload Successful", url)
return {
"headers": { "Content-Type": "application/json" },
"statusCode": 200,
"isBase64Encoded": False,
"body": str(url)
}
except FileNotFoundError:
print("The file was not found")
return {
"headers": { "Content-Type": "application/json" },
"statusCode": 404,
"isBase64Encoded": False,
"body": "File not found"
}
**DOWNLOAD **
import json
import boto3
import botocore
import base64
from botocore.vendored import requests
def lambda_handler(event, context):
s3 = boto3.client('s3')
data = json.loads(event["body"])
file = data["thefile"]
try:
response = s3.get_object(Bucket=BUCKET_NAME, Key=file,)
download_file = response["Body"].read()
filereturn = base64.b64encode(download_file).decode("utf-8")
return {
"headers": { "Content-Type": "application/json" },
"statusCode": 200,
"body": json.dumps(filereturn),
"isBase64Encoded": True,
"File Downloaded": "File Downloaded successfully"
}
except Exception as e:
return {
"headers": { "Content-Type": "application/json" },
"statusCode": 404,
"body": "Error: File not found!"
}
Can anyone tell me what I'm doing wrong? The Lambdas have full access to S3 in their policy, I've even switched off authorisation and made the bucket public in case it was a permissions error but still nothing. It must be something stupid im either forgetting or have mis-coded but I cant for the life of me figure it out!