DynamoDB and Boto3 error on BatchGetItem operation: "The provided key element does not match the schema"

Question

I am having difficulty with the Boto3/DynamoDB BatchGetItem operation. I would greatly appreciate any help or guidance! I'm pretty new to python/aws so sorry in advanced if this is a novice question.

When I perform the operation, I get this error:

botocore.exceptions.ClientError: An error occurred (ValidationException) when calling the BatchGetItem operation: The provided key element does not match the schema

Here is my code:

import boto3
dynamodb = boto3.resource('dynamodb', region_name='us-west-2')
response = dynamodb.batch_get_item(
    RequestItems={
        'test': {
            'Keys': [
                {
                    'item_ID': {
                        'S': '1'
                    }
                },
                {
                    'item_ID': {
                        'S': '2'
                    }
                }
            ],
            'ProjectionExpression': 'item_ID, color',
        }
    }
)

This is a screen-cap of the items in the table.

This is a screen-cap of the table details, showing the partition key is 'item_ID' and that it's a 'string'

Here is the fulll error message:

Traceback (most recent call last):
File "C:/Users/Henry Miller/PycharmProjects/bioinformatics_webapp/get_items.py", line 18, in <module>
'ProjectionExpression': 'item_ID, color',
File "C:\Users\Henry Miller\PycharmProjects\bioinformatics_webapp\venv\lib\site-packages\boto3\resources\factory.py", line 520, in do_action
response = action(self, *args, **kwargs)
File "C:\Users\Henry Miller\PycharmProjects\bioinformatics_webapp\venv\lib\site-packages\boto3\resources\action.py", line 83, in __call__
response = getattr(parent.meta.client, operation_name)(**params)
File "C:\Users\Henry Miller\PycharmProjects\bioinformatics_webapp\venv\lib\site-packages\botocore\client.py", line 314, in _api_call
return self._make_api_call(operation_name, kwargs)
File "C:\Users\Henry Miller\PycharmProjects\bioinformatics_webapp\venv\lib\site-packages\botocore\client.py", line 612, in _make_api_call
raise error_class(parsed_response, operation_name)
botocore.exceptions.ClientError: An error occurred (ValidationException) when calling the BatchGetItem operation: The provided key element does not match the schema

Answer 1

Answering my own question here... but it turns out that you need to use boto3.client instead of boto3.resouce. Here is the updated code which works:

import boto3
dynamodb = boto3.resource('dynamodb', region_name='us-west-2')
client = boto3.client('dynamodb', region_name='us-west-2')
response = client.batch_get_item(
    RequestItems={
        'test': {
            'Keys': [
                {
                    'item_ID': {
                        'S': '1'
                    }
                },
                {
                    'item_ID': {
                        'S': '2'
                    }
                }
            ],
            'ProjectionExpression': 'item_ID, color',
        }
    }
)

And here was the response:

"C:\Users\Henry Miller\PycharmProjects\bioinformatics_webapp\venv\Scripts\python.exe" "C:/Users/Henry Miller/PycharmProjects/bioinformatics_webapp/get_items.py"
{'Responses': {'test': [{'item_ID': {'S': '1'}, 'color': {'S': 'red'}}, {'item_ID': {'S': '2'}, 'color': {'S': 'blue'}}]}, 'UnprocessedKeys': {}, 'ResponseMetadata': {'RequestId': 'BAH1SHCBHOMRJMJ5AHE7VRTON3VV4KQNSO5AEMVJF66Q9ASUAAJG', 'HTTPStatusCode': 200, 'HTTPHeaders': {'server': 'Server', 'date': 'Tue, 31 Jul 2018 04:15:13 GMT', 'content-type': 'application/x-amz-json-1.0', 'content-length': '130', 'connection': 'keep-alive', 'x-amzn-requestid': 'BAH1SHCBHOMRJMJ5AHE7VRTON3VV4KQNSO5AEMVJF66Q9ASUAAJG', 'x-amz-crc32': '1917096114'}, 'RetryAttempts': 0}}

Process finished with exit code 0