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AWS Lambda Python Code


Hi Dears, Hope all is good

I have lambda function written in python (event driven ETL), I use two packaged functions to handel one csv file. I want to use the input csv file (S3 object uploaded to the bucket) in the two functions and put two json files in two different s3 buckets as an output.

But When I used the code as below, It convert the first function(df_out_1) successfully but in second function (df_out_2) give me error message that " No columns to parse from file " for the second function :

The code as below:

def lambda_handler(event, context):

s3_client = boto3.client('s3')
s3 = boto3.resource('s3')

if event:
        obj = event['Records'][0]
        bucket_name = obj['s3']['bucket']['name']
        file = obj['s3']['object']['key']
        csv_object = s3_client.get_object(Bucket = bucket_name , Key = file)
        csv_content = csv_object['Body'].read()
        bite = io.BytesIO(csv_content)

        df_out_1 = csv_json_function_alex_dep(bite)
        s3.Object('midibus-sagemaker-ai-engine-2' , jsonkey ).put(Body=json.dumps(df_out_1))
        print('The file is converted successfully for model-1 input!')
        #change input later to be jsonkey
        df_out_2 = csv_json_function_alex_arri(bite)
        s3.Object('midibus-sagemaker-ai-engine-2',  jsonkey ).put(Body=json.dumps(df_out_2))
        print('The file is converted successfully for model-2 input!')

        return {
        'statusCode': 200,
        'body': json.dumps('The file is converted successfully!')
    except BaseException as err:
        print("Oops! Something went wrong ! \\n")

        return {
        'statusCode': 400,
        'body': json.dumps('Something went wrong!')

thanks, Basem

2 Answers
Accepted Answer

Have you tried doing bite = io.BytesIO(csv_content) again before the second function call?

answered a month ago
  • Thanks!! It works well, Why we put it again with the second function?


If your first function uses to get the content of the buffer, the internal buffer cursor will be advanced to the end of the buffer and a subsequent read() call will return an empty buffer. You can reset the cursor to the beginning of the buffer using Alternatively, if you can control how the functions you invoke are reading data from the buffer, you could usebite.getvalue().

answered a month ago
  • Thanks for your proposed solution, I used the above answer and it works well now.

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