TransactWrite 期间 PynamoDB 的 NoCredentialError

如何解决TransactWrite 期间 PynamoDB 的 NoCredentialError

我正在尝试使用 pynamodb 库（例如）从 Python 应用程序的事务中删除 2 个 DynamoDB 表中的项目

from pynamodb.connection import Connection
from pynamodb.transactions import TransactWrite
...
...
try:
    product = ProductModel.get(pid)
    block = BlockModel.get(bid)

    app.logger.info(f'Deleting product: {product.pid},block: {block.bid}')
    connection = Connection()

    with TransactWrite(connection=connection,client_request_token='some-random-token') as transaction:
        transaction.delete(product)
        transaction.delete(block)

except Exception:
    app.logger.error('Failed...',exc_info=True)

这总是失败：

...
...
File "[myvirtualenv]/python3.8/site-packages/botocore/auth.py",line 357,in add_auth
  raise NoCredentialsError
botocore.exceptions.NoCredentialsError: Unable to locate credentials  

During handling of the above exception,another exception occurred:

Traceback (most recent call last):
...
...
[myvirtualenv]/python3.8/site-packages/pynamodb/connection/base.py",line 1081,in transact_write_items
    raise TransactWriteError("Failed to write transaction items",e)
pynamodb.exceptions.TransactWriteError: Failed to write transaction items

在检索项目之后，尝试删除事务之前，我可以看到日志记录。我的模型看起来像：

from pynamodb.models import Model
from pynamodb.attributes import UnicodeAttribute

class ProductModel(Model):
    
    class Meta:
        table_name = 'Product'
        region = 'eu-west-1'
        aws_access_key_id = os.environ.get('AWS_ACCESS_KEY')
        aws_secret_access_key = os.environ.get('AWS_SECRET_KEY')
        
    pid = UnicodeAttribute(hash_key=True)
    ...

BlockModel 类似。如果我不将删除包装在事务中，则没有问题。这是我第一次尝试使用事务。 Connection 对象似乎没有构造函数的任何凭据参数。还有什么我需要做的吗？