How to handle try and exception in python for bucket list empty-CodePudding

I am trying to handle not none or empty list exception while using boto3. I want to know is there any good way of pythonic code to write this.

try:        
    my_region = os.environ['AWS_REGION']
    if my_region == 'us-east-1':
        try:
            s3 = boto3.client('s3')
            buckets_list = s3.list_buckets()
        except Exception as err:
            logging.error('Exception was thrown in connection %s' % err)
            print("Error in connecting and listing bucket{}".format(err))
        if buckets_list['Buckets']:
            # Search for all buckets.
            for bucket in buckets_list['Buckets']:
            # my code follow to get other things...
            
        else:
            print("Buckets are empty in this region")
    else:
        print("Region not available")
        raise Exception("Exception was thrown in Region")    

except Exception as err:
    logging.error('Exception was thrown %s' % err)
    print("Error is {}".format(err))
    raise err

Is this the right way or any suggestions would help.

CodePudding user response：

Your code is somewhat not detailed enough, at least the beginning of the function should have been shared. Anyway, did you consider:

 try:
          s3 = boto3.client('s3')
         buckets_list = s3.list_buckets()
         print("buckets_list", buckets_list['Buckets'])
    
        print("Error is {}".format(err))
         if buckets_list['Buckets'] is not None: ##Here I am trying to check if buckets are empty
        # Search for all buckets.
        for bucket in buckets_list['Buckets']:
     (your other codes)


except Exception as err:
        logging.error('Exception was thrown in connection %s' % err)

CodePudding user response：

You can use else block of the try except suite. It is useful for code that must be executed if the try clause does not raise an exception.

try:
    s3 = boto3.client('s3')
    buckets_list = s3.list_buckets()
except Exception as err:
    logging.error('Exception was thrown in connection %s' % err)
    print("Error is {}".format(err))
else:
    # This means the try block is succeeded, hence `buckets_list` variable is set.
    for bucket in buckets_list['Buckets']:
        # Do something with the bucket

One issue I am seeing from your code is that, if the list_buckets call is failed there is a chance to get NameError at the line if buckets_list['Buckets'] is not None:. Because buckets_list is undefined if the buckets_list call is failed. To understand this try to run the following snippet :)

try:
    a = (1/0)
except Exception as e:
    print(e)

print(a)