Wednesday, 31 August 2016

Python script to move records from CSV File to a Dynamodb table



Write a python script to move records from a csv file to a dynamo db table. 


Solution

# Script to write csv records into dynamo db table.
# For help on prerequisites and running this script, read this blog.

from __future__ import print_function # Python 2/3 compatibility
from __future__ import division #Python 2/3 compatiblity for integer division
import argparse
import boto3
import csv
import time

# command line arguments
parser = argparse.ArgumentParser(description='Write CSV records to dynamo db table. CSV Header must map to dynamo table field names.')
parser.add_argument('csvFile', help='Path to csv file location')
parser.add_argument('table', help='Dynamo db table name')
parser.add_argument('writeRate', default=5, type=int, nargs='?', help='Number of records to write in table per second (default:5)')
parser.add_argument('delimiter', default='|', nargs='?', help='Delimiter for csv records (default=|)')
parser.add_argument('region', default='us-west-2', nargs='?', help='Dynamo db region name (default=us-west-2')
args = parser.parse_args()
print(args)

# dynamodb and table initialization
endpointUrl = "https://dynamodb." + args.region + ".amazonaws.com"
dynamodb = boto3.resource('dynamodb', region_name=args.region, endpoint_url=endpointUrl)
table = dynamodb.Table(args.table)

# write records to dynamo db
with open(args.csvFile) as csv_file:
    tokens = csv.reader(csv_file, delimiter=args.delimiter)
    # read first line in file which contains dynamo db field names
    header = tokens.next();
    # read second line in file which contains dynamo db field data types
    headerFormat = tokens.next();
    # rest of file contain new records
    for token in tokens:
       item = {}
       for i,val in enumerate(token):
         if val:
           key = header[i]
           if headerFormat[i]=='int':
             val = int(val)
           item[key] = val
       print(item)
       table.put_item(Item = item)

       time.sleep(1/args.writeRate) # to accomodate max write provisioned capacity for table

Preconditions

  • Install boto3 python package on your box
  • Set up AWS credentials
  • Dynamodb field data type is either int or string. New data type will require improvements in code.
  • CSV first two lines are always header and header data type.

Script Arguments

Mandatory
  • csvFile - Path to csv file location
  • table - Dynamo db table name
Optional
  • writeRate - Number of records to write in table per second (default:5)
  • delimiter - Delimiter for csv records (default=|)
  • region - Dynamo db region name (default=us-west-2)

Sample Input

field1|field2|field3|field4|field5
string|string|string|string|int
GZ6MHDMM0IB1IR0P|A27LZ9R92G1SJ|OPEN||1

Sample Run

  • python csvToDynamodb.py abc.csv ABC
  • python csvToDynamodb.py abc.csv ABC 50 | us-east-1

Future improvements

  • Add conversion log for other dynamo db data types. If for concerned table Dynamo db fields have format other than string or int, we will have to convert CSV string value to dynamo db field type required.

Help

  • python csvToDynamodb.py -h

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