quadtree_lambda.py

'''
  For detailed information on API call, please checkout official boto3 website.
  => https://boto3.readthedocs.io/en/latest/reference/services/s3.html#S3.Bucket.copy

  Please checkout my github for more information.
  => https://github.com/shawnkoon/aws_python_practice

  @purpose: Receives an csv file from s3 bucket,
            parse & creates a json tree node object and uploads it into dynamodb.
  python v3.6
'''
import json
import decimal
import boto3

# Get s3 client.
S3_CLIENT = boto3.client('s3')
DYNAMO_RESOURCE = boto3.resource('dynamodb')
DYNAMO_DB_TABLE_NAME = 'tf-quadtree-dynamodb'

def get_bucket_name(event):
    '''
    Get bucket name from incomming event.
    @param event : Received event.
    '''
    return event['Records'][0]['s3']['bucket']['name']

def get_key_name(event):
    '''
    Get key name from incomming event.
    @param event : Received event.
    '''
    return event['Records'][0]['s3']['object']['key']

def to_string(byte_object):
    '''
    Converts Byte object into String object.
    @param byte_object : Source Byte object.
    -> Returns String object.
    '''
    return byte_object.decode("utf-8")

def read_object(bucket_name, key_name):
    '''
    Reads object from given bucket with matching key.
    @param bucket_name : Source bucket name.
    @param key_name : Source key name.
    -> Returns s3 object.
    '''
    return S3_CLIENT.get_object(
        Bucket=bucket_name,
        Key=key_name
    )

def print_detail(event, context):
    '''
    Prints the detail of the event & context.
    @param event : received event.
    @param context : current context info.
    '''
    print('Received event: ' + json.dumps(event, indent=2))
    print('Current function: ' + context.function_name)

def get_dynamo_db_table():
    '''Gets DynamoDB table object'''
    return DYNAMO_RESOURCE.Table(DYNAMO_DB_TABLE_NAME)

def put_dynamo_db_object(table, objest_row):
    '''
    Put object row into DynamoDB table with proper format.
    @param object_row : Row || str form of object to be inserted into DynamoDB
    '''
    object_row_list = objest_row.strip().split(',')
    print('object_row_list : ', end='')
    print(object_row_list)
    table.put_item(
        Item={
            'id': object_row_list[0],
            'coordinate': {
                'xMin': decimal.Decimal(object_row_list[1]),
                'yMin': decimal.Decimal(object_row_list[2]),
                'xMax': decimal.Decimal(object_row_list[3]),
                'yMax': decimal.Decimal(object_row_list[4]),
            },
            'data': {

            },
        }
    )

def launch_container(event, context):
    '''
    Lambda entry function that receives event & context.
    @param event : received event.
    @param context : current context info.
    '''
    try:
        print_detail(event, context)
        src_bucket = get_bucket_name(event)
        src_key = get_key_name(event)

        s3_object = read_object(src_bucket, src_key)
        s3_object_list = to_string(s3_object['Body'].read()).strip().split('\n')
        dynamo_db_object = get_dynamo_db_table()
        for s3_object_row in s3_object_list:
            print('=> About to put a row into the DynamoDB table :')
            put_dynamo_db_object(dynamo_db_object, s3_object_row)
            print('=> Successfully inserted row into the table.')

    except Exception as error:
        print(error)
        raise error