DynamoDB和Boto3操作中的BatchGetItem错误：“提供的键元素与模式不匹配”

Question

我对Boto3 3/DynamoDB BatchGetItem操作有困难。我将非常感谢任何帮助或指导！我对python/aws非常陌生，如果这是个新手问题的话，很抱歉。

当我执行该操作时，会得到以下错误：

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

这是我的代码：

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',
        }
    }
)

这是表中物品的屏幕盖.

ID和它是一个‘字符串’

以下是完整的错误消息：

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

在这里回答我自己的问题。但是事实证明，您需要使用boto3.client而不是boto3.resouce。以下是工作的更新代码：

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',
        }
    }
)

以下是他们的回应：

"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

Answer 2

您也可以使用but 3资源版本，但在这种情况下不要传递键的类型。您的代码应该如下所示：

import boto3
dynamodb = boto3.resource('dynamodb')
response = dynamodb.batch_get_item(
    RequestItems={
        'test': {
            'Keys': [
                {'item_ID': 'ID1_value'},
                {'item_ID': 'ID2_value'}
            ]
        }
    }
)

这里有一个关于GitHub的完整的工作示例：batching.py。