是否存在用于将批处理获取请求提交到AWS DynamoDB的Python API？ [英] Is there a Python API for submitting batch get requests to AWS DynamoDB?

问题描述

boto3 软件包-亚马逊的Python官方AWS API包装器-对将项目批量上传到DynamoDB具有强大的支持。看起来像这样：

The package boto3 - Amazon's official AWS API wrapper for python - has great support for uploading items to DynamoDB in bulk. It looks like this:

db = boto3.resource("dynamodb", region_name = "my_region").Table("my_table")

with db.batch_writer() as batch:
    for item in my_items:
        batch.put_item(Item = item)

此处 my_items 是Python字典的列表，每个字典都必须具有表的主键（ s）。这种情况并不完美-例如，没有安全机制可以阻止您超出吞吐量限制-但这仍然相当不错。

Here my_items is a list of Python dictionaries each of which must have the table's primary key(s). The situation isn't perfect - for instance, there is no safety mechanism to prevent you from exceeding your throughput limits - but it's still pretty good.

但是，没有似乎是从数据库读取的任何副本。我能找到的最接近的是 DynamoDB.Client.batch_get_item（），但是这里的API非常复杂。这是请求两个项目的样子：

However, there does not appear to be any counterpart for reading from the database. The closest I can find is DynamoDB.Client.batch_get_item(), but here the API is extremely complicated. Here's what requesting two items looks like:

db_client = boto3.client("dynamodb", "my_region")

db_client.batch_get_item(
    RequestItems = {
        "my_table": {
            "Keys": [
                {"my_primary_key": {"S": "my_key1"}},
                {"my_primary_key": {"S": "my_key2"}}
            ]
        }
    }
)

这是可以容忍的，但响应具有相同的问题：所有值都是字典，其键为数据类型（ S 表示字符串， N 表示数字， M 表示映射等），并且不得不解析所有内容，这有点烦人。所以我的问题是：

This might be tolerable, but the response has the same problem: all values are dictionaries whose keys are data types ("S" for string, "N" for number, "M" for mapping, etc.) and it is more than a little annoying to have to parse everything. So my questions are:

是否有本地的 boto3 支持从批处理读取DynamoDb，类似于上面的 batch_writer 函数？

Is there any native boto3 support for batch reading from DynamoDb, similar to the batch_writer function above?

失败了，

boto3 是否提供任何内置方法来自动反序列化对 DynamoDB.Client.batch_get_item（）函数？

Does boto3 provide any built-in way to automatically deserialize the responses to the DynamoDB.Client.batch_get_item() function?

我还要补充一点函数 boto3.resource（ dynamodb）。Table（）。get_item（）具有我认为是正确的API，因为没有类型解析输入或输出所必需。因此，似乎这是开发人员的某种监督，我想我正在寻找一种解决方法。

I'll also add that the function boto3.resource("dynamodb").Table().get_item() has what I would consider to be the "correct" API, in that no type-parsing is necessary for inputs or outputs. So it seems that this is some sort of oversight by the developers, and I suppose I'm looking for a workaround.

推荐答案

因此，值得庆幸的是，您可能会发现有用的东西-非常类似于 json 模块，该模块具有 json.dumps 和 json.loads ，boto3有一个类型模块，其中包含序列化程序和反序列化程序。请参见TypeSerializer / TypeDeserializer 。如果您查看源代码，则序列化/反序列化是递归的，并且对于您的用例而言应该是完美的。

So thankfully there is something that you might find useful - much like the json module which has json.dumps and json.loads, boto3 has a types module that includes a serializer and deserializer. See TypeSerializer/TypeDeserializer. If you look at the source code, the serialization/deserialization is recursive and should be perfect for your use case.

注意：建议您使用二进制 / 十进制，而不是仅使用常规的旧python float / int进行往返转换。

Note: Its recommended that you use Binary/Decimal instead of just using a regular old python float/int for round trip conversions.

serializer = TypeSerializer()
serializer.serialize('awesome') # returns {'S' : 'awesome' }

deser = TypeDeserializer()
deser.deserialize({'S' : 'awesome'}) # returns u'awesome'

希望这会有所帮助！

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