aws cli dynamo db (ValidationException) 错误

Question

我正在寻找使用 python 的 boto3 模块向 dynamodb 批量写入项目，我得到了这个。这是我第一次使用 aws cli 或 boto3。文档说当存在空值和可能不正确的数据类型时会发生验证异常错误，但我已经玩过所有这些并且它似乎不起作用。

dynamodb 是否只喜欢一次写入 25 个项目？如果是这样，我如何控制这些批次？

我的请求：

client = boto3.client('dynamodb')
response = client.batch_write_item(RequestItems=batch_dict)

batch_dict 的顶部：

{'scraper_exact_urls': [{'PutRequest': {'Item': {'Sku': {'S': 'T104P3'},
 'pps_id': {'N': '427285976'},
 'scraper_class_name': {'S': 'scraper_class_name'},
 'store_id': {'N': '1197386754'},
 'updated_by': {'S': 'user'},
 'updated_on': {'N': '1480714223'},
 'updated_url': {'S': 'http://www.blah.com'}}}},
 {'PutRequest': {'Item': {'Sku': {'S': 'T104P3'},
 'pps_id': {'N': '427285976'},
 'scraper_class_name': {'S': 'scraper_class_name'},
 'store_id': {'N': '1197386754'},
 'updated_by': {'S': 'user'},
 'updated_on': {'N': '1480714223'},
 'updated_url': {'S': 'http://www.blah.com'}}}},....

架构：

属性：“pps_id”=>\Aws\DynamoDb\Enum\Type::NUMBER、“sku”=>\Aws\DynamoDb\Enum\Type::STRING、“scraper_class_name”=>\Aws\DynamoDb\Enum\Type： :STRING, "store_id"=>\Aws\DynamoDb\Enum\Type::NUMBER, "updated_url"=>\Aws\DynamoDb\Enum\Type::STRING, "updated_by"=>\Aws\DynamoDb\Enum\Type ::STRING, "updated_on"=>\Aws\DynamoDb\Enum\Type::NUMBER, 字段: "pps_id", "scraper_class_name",

错误：

ClientError: An error occurred (ValidationException) when calling the    BatchWriteItem operation: 1 validation error detected: Value .... Map value   must satisfy constraint: [Member must have length less than or equal to 25,   Member must have length greater than or equal to 1]

Answer 1

BatchWriteItem API 一次处理 25 个项目。您可以使用以下改编自非复制批处理问题的代码，在 25 个项目块上调用 BatchWriteItem

def batch(iterable, n=1):
    l = len(iterable)
    for ndx in range(0, l, n):
        yield iterable[ndx:min(ndx + n, l)]

client = boto3.client('dynamodb')

for x in batch(batch_dict['scraper_exact_urls'], 25):
    subbatch_dict = {'scraper_exact_urls': x}
    response = client.batch_write_item(RequestItems=subbatch_dict)