How to handle ConditionalCheckFailedException

My code looks like below:

try:
    cust_table.put_item(Item=company,
                    ConditionExpression=Attr('version').eq(previous_version))
except botocore.errorfactory.ConditionalCheckFailedException as ex:
  print(ex)

I’m getting this error

# botocore.errorfactory.ConditionalCheckFailedException: An error occurred (ConditionalCheckFailedException) when calling the PutItem operation: The conditional request failed

# During handling of the above exception, another exception occurred:

# Traceback (most recent call last):
#   File "/home/ganesh/code/vantage-trials-site-reassignment-service/createUser/src/test.py", line 45, in <module>
#     except botocore.errorfactory.ConditionalCheckFailedException as ex:
# AttributeError: module 'botocore.errorfactory' has no attribute 'ConditionalCheckFailedException'

What exception to catch?

[swetashre]

@ghsatpute - You can achieve the same using the errorfactory which will create an error class based on the codes returned. This was added here

import boto3

res = boto3.resource('dynamodb')
table = res.Table('mytable') 

try: 
    conditionalUpdateResponse = table.put_item(Item={'test':'testing20'},ConditionExpression='attribute_exists(test)')
except res.meta.client.exceptions.ConditionalCheckFailedException as e: 
    print(e)

Hope this helps. We don’t have very good documentation about how to use errorfactory.

[ghsatpute]

So as per my experience with programming. We catch exceptions which have been raised or their parent. For example, if a code raises FileNotFoundException we catch FileNotFoundException or it’s parent IOException if you don’t want to differentiate between types of exception.

Here, the code is raising ConditionalCheckFailedException, I should be able to catch the same exception. Here we are catching some other exception and writing logic inside to check whether it’s a part of the exception.

Obviously, this functionally works, but the working code is not everything.