Not able to get item from AWS dynamodb using python

Question

my python code

import boto3 
from boto3 import dynamodb 

from boto3.session import Session

from boto3.dynamodb.conditions import Key, Attr


dynamodb_session = Session(aws_access_key_id='XXXXXXXXXXXXXXX',
          aws_secret_access_key='XXXXXXXXXXXXXXXXXXXXXXXXXXXX',
          region_name='us-east-1')

dynamodb = dynamodb_session.resource('dynamodb')

table=dynamodb.Table('Garbage_collector_table')

my_topic = "$aws/things/garbage_collector_thing/shadow/update/accepted"

response = table.get_item(TableName='Garbage_collector_table', Key={'topic':my_topic})

for res in response: 
    print "result ",res

I am getting the following error

Traceback (most recent call last):
 File "get-data-dynamodb-boto3.py", line 19, in <module>
    response = table.get_item(TableName='Garbage_collector_table', Key={'topic': my_topic})   File
 "/usr/local/lib/python2.7/dist-packages/boto3/resources/factory.py",
 line 518, in do_action
     response = action(self, *args, **kwargs)   File "/usr/local/lib/python2.7/dist-packages/boto3/resources/action.py",
 line 83, in __call__
     response = getattr(parent.meta.client, operation_name)(**params)   File "/usr/local/lib/python2.7/dist-packages/botocore/client.py", line
 258, in _api_call
     return self._make_api_call(operation_name, kwargs)   File /usr/local/lib/python2.7/dist-packages/botocore/client.py", line 548,
 in _make_api_call
     raise ClientError(parsed_response, operation_name)

Answer 1

You are mixing resource and client objects which have different methods.

The correct syntax for the resource is 

response= get_item(Key={'topic':my_topic})

but personally I recommend using boto client 

client= boto3.client('dynamodb')

response=client.get_item(TableName='garbage_collector_table', Key= {'topic':'S': str(my_topic)}})