title: Not able to get_item from AWS dynamodb using python?
body: <p>I am new to dynamodb trying to get data from dynamodb.</p>
  
  <p><a href="https://i.stack.imgur.com/GVoXN.jpg" rel="noreferrer">This is my table with "topic" as a primary hash key</a></p>
  
  <p>my python code</p>
  
  <pre><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
  </code></pre>
  
  <p>I am getting the following error</p>
  
  <pre><code>Traceback (most recent call last):
   File "get-data-dynamodb-boto3.py", line 19, in &lt;module&gt;
      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)
  </code></pre>
  
  <blockquote>
    <p>botocore.exceptions.ClientError: An error occurred
    (ValidationException) when calling the GetItem operation: The provided
    key element does not match the schema</p>
  </blockquote>
  
  <p>am I missing anything in my code?</p>