CODEWITHSUNDEEP
amazon-dynamodbaws-lambdaboto3
Reid
Reid

Reputation: 4524

Boto Scan Filterexpression : Invalid type for parameter

I am trying to use the following code, but I am unable to get it to work. It keeps giving me an error message about the filter expression being the incorrect type, even though I am doing exactly what is done in the documentation. What can I do to fix this?

def EndpointDeleted(event):
    endpoint = event['Attributes']['EndpointArn']
    if('EndpointArn' in event['Attributes']):
        client = boto3.client('dynamodb')
        response = client.scan(
            TableName='sniffergps-mobilehub-812282467-Users',
            Select='ALL_ATTRIBUTES',
            FilterExpression=Attr('Endpoints').contains(endpoint)
        )
        return response

But I get an error saying that the filter expression is the incorrect type. I have the following import messages: import boto3 from boto3.dynamodb.conditions import Key from boto3.dynamodb.conditions import Attr

Error message:

{
  "errorMessage": "Parameter validation failed:\nInvalid type for parameter FilterExpression, value: <boto3.dynamodb.conditions.Contains object at 0x7fdca25e0b38>, type: <class 'boto3.dynamodb.conditions.Contains'>, valid types: <class 'str'>",
  "errorType": "ParamValidationError",
  "stackTrace": [
    [
      "/var/task/lambda_function.py",
      13,
      "lambda_handler",
      "return EndpointDeleted(event)"
    ],
    [
      "/var/task/lambda_function.py",
      24,
      "EndpointDeleted",
      "FilterExpression=Attr('Endpoints').contains(endpoint)"
    ],
    [
      "/var/runtime/botocore/client.py",
      312,
      "_api_call",
      "return self._make_api_call(operation_name, kwargs)"
    ],
    [
      "/var/runtime/botocore/client.py",
      575,
      "_make_api_call",
      "api_params, operation_model, context=request_context)"
    ],
    [
      "/var/runtime/botocore/client.py",
      630,
      "_convert_to_request_dict",
      "api_params, operation_model)"
    ],
    [
      "/var/runtime/botocore/validate.py",
      291,
      "serialize_to_request",
      "raise ParamValidationError(report=report.generate_report())"
    ]
  ]
}

Upvotes: 3

Views: 13100

Answers (1)

Mark B
Mark B

Reputation: 200486

Note the difference in syntax between the Boto3 DynamoDB Client, and the Table Resource.

The FilterExpression parameter for DynamoDB client expects a string.

The method you are using to set the FilterExpression parameter looks like the way you would use a DynamoDB.Table resource.

Upvotes: 22

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