Add explanation on how to catch boto3 exceptions

[schumannd]

The problem I have with the boto3 documentation can be found here: https://stackoverflow.com/questions/46174385/properly-catch-boto3-errors

Am I doing this right? Or what is best practice when dealing with boto3 exceptions? Can this be added to the wiki?

[stealthycoin]

I'm not sure what wiki page you mean? Do you mean the documentation? Thats not a wiki its generated from the models. So botocore will raise a ClientError which you can always catch for any sort of issue you can then check the code. There is also a newer style of error catching that you can do using the errorfactory which will create an error class based on the codes returned. This was added here. This is not currently documented, we will need to update our documentation generator to add this to the docs. I will mark this as a documentation feature request.

[schumannd]

Yes, I am talking about the errorfactory documentation. Thanks

[Netherdrake]

I had the same question, until I realized that all service exceptions are tucked nicely in .exceptions of the resource/client.

For example, if using iam service:

iam = boto3.client('iam')

try:
    response = iam.create_role(
        Path='/',
        RoleName='Elastic_Transcoder_Viewly_Role',
        AssumeRolePolicyDocument=trust_policy,
        Description='Default Role'
    )
except iam.exceptions.EntityAlreadyExistsException:
    pass

[schumannd]

I use this in the linked SO article. My issue is, that I can't find an overview of what exceptions exist. Having the exceptions in .exceptions of the resource/client is also not ideal when e.g. writing tests as you usually don't have the resource object available there.

[ezramorris]

I'm not sure this always works. I have dynamodb = boto3.resource('dynamodb') but when attempting to except dynamodb.exceptions.ConditionalCheckFailedException I get AttributeError: 'dynamodb.ServiceResource' object has no attribute 'exceptions'.

[ldoran]

@ezramorris You'll need to use boto3.client('dynamodb') to be able to access exceptions, it doesn't work with resources.

[biosopher]

We still need a good explanation on how to catch boto3 errors. E.g. this is a common approach that I've seen but it doesn't work in my case:

try:
            cos_client.download_fileobj(bucket_name, object_key, file)
        except ibm_boto3.exceptions.ibm_botocore.client.ClientError as e:
            print('Error: {}.'.format(e.response['Error']['Message']))
            raise e
        except:
            print(e.__dict__)
            e = sys.exc_info()[0]
            if e.response != None:
                print("Detailed error: ",e.response )

[gyoza]

        from botocore.exceptions import ClientError

        except ClientError as e:
            error_code = e.response['Error']['Code']

in other words, e.response should always contain something.. maybe not always { "Error" { "Message": "xx"} format...

you may want to get rid of

        except ibm_boto3.exceptions.ibm_botocore.client.ClientError as e:

and replace with just

from ibm_boto3.exceptions.ibm_botocore.client import ClientError
except ClientError as e: 

which may be why you're having issues.

[biosopher]

@gyoza Already got that as shown above. My question is how to get the error message out of ClientError.

[gyoza]

updated.

[biosopher]

Very odd. I just got this error when using your recommended code above:

from ibm_boto3.exceptions.ibm_botocore.client import ClientError
      2 
      3 def download_object_from_cos(cos_client, bucket_name, object_key):
      4     import ibm_boto3
      5     import sys

ImportError: No module named 'ibm_boto3.exceptions.ibm_botocore'; 'ibm_boto3.exceptions' is not a package

[gyoza]

Maybe try removing IBM botocore and boto3 and just use public domain version... It's hard to say on a forked library..

…

On Tue, Apr 24, 2018, 9:49 AM Anthony Stevens ***@***.***> wrote: Very odd. I just got this error when using your recommended code above: from ibm_boto3.exceptions.ibm_botocore.client import ClientError 2 3 def download_object_from_cos(cos_client, bucket_name, object_key): 4 import ibm_boto3 5 import sys ImportError: No module named 'ibm_boto3.exceptions.ibm_botocore'; 'ibm_boto3.exceptions' is not a package — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#1262 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAibBtgw0bZlwny8xjjuv6KLn-wYBBZCks5tr1eLgaJpZM4PWJwe> .