title: How to use filter expressions on aws using python3 for nested map attribute?
body: <p>I have been trying to scan DynamoDB to check for particular value in a nested map attribute named deliverables. However using scan with filter expressions is resulting in an empty result.</p>
  <pre><code>import boto3
  result = []
  dynamo_client = boto3.client(&quot;dynamodb&quot;)
  paginator = dynamo_client.get_paginator(&quot;scan&quot;)
  
  operation_parameters = {
      'FilterExpression': &quot;#Deliverable= :deliverable&quot;,
      'ExpressionAttributeNames': {
          '#Deliverable': 'deliverables.fc986523-a666-478e-8303-2a1c3c1dc4ba'
      },
      'ExpressionAttributeValues': {
      ':deliverable':  {
      &quot;M&quot;: {
       &quot;read&quot;: {
        &quot;BOOL&quot;: True
       },
       &quot;upload&quot;: {
        &quot;BOOL&quot;: True
       },
       &quot;write&quot;: {
        &quot;BOOL&quot;: True
       }
      }
      }
    }
  }
  for page in paginator.paginate(TableName=&quot;TableName&quot;, **operation_parameters):
      result.append(page[&quot;Items&quot;])
  
  print(result)
  </code></pre>
  <p>The items in the dynamo db look like this:</p>
  <pre><code>[
     [
        {
           &quot;deliverables&quot;:{
              &quot;M&quot;:{
                 &quot;7397d832-fefb-4ba2-97a1-0f6e73d611d9&quot;:{
                    &quot;M&quot;:{
                       &quot;read&quot;:{
                          &quot;BOOL&quot;:true
                       },
                       &quot;upload&quot;:{
                          &quot;BOOL&quot;:true
                       },
                       &quot;write&quot;:{
                          &quot;BOOL&quot;:true
                       }
                    }
                 },
                 &quot;fc986523-a666-478e-8303-2a1c3c1dc4ba&quot;:{
                    &quot;M&quot;:{
                       &quot;read&quot;:{
                          &quot;BOOL&quot;:true
                       },
                       &quot;upload&quot;:{
                          &quot;BOOL&quot;:true
                       },
                       &quot;write&quot;:{
                          &quot;BOOL&quot;:true
                       }
                    }
                 }
              }
           },
           &quot;username&quot;:{
              &quot;S&quot;:&quot;username1&quot;
           },
           &quot;deniedReferences&quot;:{
              &quot;L&quot;:[
                 
              ]
           }
        },
        {
           &quot;deliverables&quot;:{
              &quot;M&quot;:{
                 &quot;7397d832-fefb-4ba2-97a1-0f6e73d611d9&quot;:{
                    &quot;M&quot;:{
                       &quot;read&quot;:{
                          &quot;BOOL&quot;:true
                       },
                       &quot;upload&quot;:{
                          &quot;BOOL&quot;:false
                       },
                       &quot;write&quot;:{
                          &quot;BOOL&quot;:false
                       }
                    }
                 },
                 &quot;fc986523-a666-478e-8303-2a1c3c1dc4ba&quot;:{
                    &quot;M&quot;:{
                       &quot;read&quot;:{
                          &quot;BOOL&quot;:true
                       },
                       &quot;upload&quot;:{
                          &quot;BOOL&quot;:false
                       },
                       &quot;write&quot;:{
                          &quot;BOOL&quot;:false
                       }
                    }
                 }
              }
           },
           &quot;username&quot;:{
              &quot;S&quot;:&quot;repositoryadmin&quot;
           },
           &quot;deniedReferences&quot;:{
              &quot;L&quot;:[
                 
              ]
           }
        }
     ]
  ]
  </code></pre>
  <p>Please let me know if you can help me solve this issue.</p>