无法使用 python 从 AWS dynamodb 获取项目？

Question

我是 dynamodb 的新手，试图从 dynamodb 获取数据。

This is my table with "topic" as a primary hash key

我的python代码

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

我收到以下错误

Traceback (most recent call last):
 File "get-data-dynamodb-boto3.py", line 19, in <module>
    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)

botocore.exceptions.ClientError：发生错误 (ValidationException) 调用 GetItem 操作时：提供的 关键元素与架构不匹配

我的代码中是否遗漏了任何内容？

Answer 1

您正在混合具有不同方法的资源和客户端对象。 More info here.

资源的正确语法是：

response = table.get_item(Key={'topic': my_topic})

但我个人建议使用 boto 客户端：

client = boto3.client('dynamodb')

response = client.get_item(TableName='Garbage_collector_table', Key={'topic':{'S':str(my_topic)}})

http://boto3.readthedocs.io/en/latest/reference/services/dynamodb.html

Answer 2

也可以查询数据库：

from boto3.dynamodb.conditions import Key

table = dynamodb.Table(table_name)
response = table.query(
    KeyConditionExpression=Key('topic').eq(my_topic)
)
items = response['Items']
if items:
    return items[0]
else:
    return []

来源：https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GettingStarted.Python.04.html

Answer 3

假设你的表中只有分区键（又名哈希键）。

import boto3
dynamodb = boto3.resource('dynamodb',region_name='ap-southeast-2')
table = dynamodb.Table('my-table')
key = {}
key['key'] = 'my-key'
print(key)
response = table.get_item(Key=key)
print(response['Item'])

Answer 4

这里有实际的例子： https://boto3.amazonaws.com/v1/documentation/api/latest/guide/dynamodb.html

在你的情况下，你需要这样做：

response = table.get_item(TableName='Garbage_collector_table', Key={'topic': my_topic})

Answer 5

我是 Lucid-Dynamodb 的作者，它是 AWS DynamoDB 的极简包装器。使用我的库可以轻松解决这个问题。

参考：https://github.com/dineshsonachalam/Lucid-Dynamodb#4-read-an-item

from LucidDynamodb.Operations import DynamoDb
import os
import logging
logging.basicConfig(level=logging.INFO)

AWS_ACCESS_KEY_ID = os.getenv("AWS_ACCESS_KEY_ID")
AWS_SECRET_ACCESS_KEY = os.getenv("AWS_SECRET_ACCESS_KEY")

if __name__ == "__main__":
    db = DynamoDb(region_name="us-east-1", 
                aws_access_key_id=AWS_ACCESS_KEY_ID, 
                aws_secret_access_key=AWS_SECRET_ACCESS_KEY)
    item = db.read_item(
        TableName="test", 
        Key={
            'topic': "1"
        })
    if(item != None):
        logging.info("Item: {}".format(item))
    else:
        logging.warning("Item doesn't exist")

Answer 6

如果你也有排序键，那么：

dynamodb = boto3.client('dynamodb', region_name=AWS_REGION, aws_access_key_id=AWS_ACCESS_KEY_ID, aws_secret_access_key=AWS_SECRET_ACCCESS_KEY)
        
response = dynamodb.get_item(
     TableName=str(os.environ['DYNAMODB_TABLE']), 
     Key={'task_id' : {
           'S' : str(task_id)
           },
          'mac' : {
           'S' : 'AA-00-04-00-XX-YX'
           }
         }
 )

Answer 7

# Have the IAM role containing policy *AmazonDynamoDBFullAccess* assigned to your lambda function

import boto3

def lambda_handler(event, context):

    try:
        dynamodb_client = boto3.client('dynamodb')
        response = dynamodb_client.get_item(
                    TableName="Garbage_collector_table",
                    Key={
                         'topic':
                                {'S':str(my_topic)}
                        }
                    )
    except Exception as error:
        print(error)
        raise
    else:
        print(f'Response = {response}')
        return response