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MoviesItemOps05.py

# # Copyright 2010-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved. # # This file is licensed under the Apache License, Version 2.0 (the "License"). # You may not use this file except in compliance with the License. A copy of # the License is located at # # http://aws.amazon.com/apache2.0/ # # This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR # CONDITIONS OF ANY KIND, either express or implied. See the License for the # specific language governing permissions and limitations under the License. # from __future__ import print_function # Python 2/3 compatibility import boto3 from botocore.exceptions import ClientError import json import decimal # Helper class to convert a DynamoDB item to JSON. class DecimalEncoder(json.JSONEncoder): def default(self, o): if isinstance(o, decimal.Decimal): if o % 1 > 0: return float(o) else: return int(o) return super(DecimalEncoder, self).default(o) dynamodb = boto3.resource('dynamodb', region_name='us-west-2', endpoint_url="http://localhost:8000") table = dynamodb.Table('Movies') title = "The Big New Movie" year = 2015 # Conditional update (will fail) print("Attempting conditional update...") try: response = table.update_item( Key={ 'year': year, 'title': title }, UpdateExpression="remove info.actors[0]", ConditionExpression="size(info.actors) > :num", ExpressionAttributeValues={ ':num': 3 }, ReturnValues="UPDATED_NEW" ) except ClientError as e: if e.response['Error']['Code'] == "ConditionalCheckFailedException": print(e.response['Error']['Message']) else: raise else: print("UpdateItem succeeded:") print(json.dumps(response, indent=4, cls=DecimalEncoder))

Sample Details

Service: dynamodb

Last tested:

Author: AWS

Type: full-example

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