Dynamo DB 掃描查詢以獲取 JSON 格式的輸出文件

Question

我對使用 boto3 的 Dynamo DB 很陌生。 我想：獲取 Dynamo DB 中所有行的掃描並將其以JSON格式存儲在文件中，以進行額外的數據處理。

我目前正在使用下面顯示的腳本來獲取詳細信息（將涉及分頁）：

from __future__ import print_function # Python 2/3 compatibility
import boto3
import json
import decimal
from boto3.dynamodb.conditions import Key, Attr

# Helper class to convert a DynamoDB item to JSON.
class DecimalEncoder(json.JSONEncoder):
    def default(self, o):
        if isinstance(o, decimal.Decimal):
            if o % 1 > 0:
                return float(o)
            else:
                return int(o)
        return super(DecimalEncoder, self).default(o)

dynamodb = boto3.resource('dynamodb')

table = dynamodb.Table('Movies')

#fe = Key('year').between(1951, 1964)
pe = "#yr, title, info.rating"
# Expression Attribute Names for Projection Expression only.
ean = { "#yr": "year", }
esk = None


response = table.scan(
#    FilterExpression=fe,
    ProjectionExpression=pe,
    ExpressionAttributeNames=ean
    )

for i in response['Items']:
    print(json.dumps(i, cls=DecimalEncoder)) 

while 'LastEvaluatedKey' in response:
    response = table.scan(
        ProjectionExpression=pe,
#        FilterExpression=fe,
        ExpressionAttributeNames= ean,
        ExclusiveStartKey=response['LastEvaluatedKey']
        )

    for i in response['Items']:
        print(json.dumps(i, cls=DecimalEncoder),)

這給了我 5000 行的示例輸出：

{"info": {"rating": 6.5}, "year": 2004, "title": "The Polar Express"}
{"info": {"rating": 5.7}, "year": 2004, "title": "The Prince & Me"}
{"info": {"rating": 5.3}, "year": 2004, "title": "The Princess Diaries 2: Royal Engagement"}
{"info": {"rating": 6.3}, "year": 2004, "title": "The Punisher"}
{"info": {"rating": 6.8}, "year": 2004, "title": "The SpongeBob SquarePants Movie"}

我無法獲得所需格式的輸出（如下所示）。 我在這里期待一個文件。

[
    {"info": {"rating": 6.5}, "year": 2004, "title": "The Polar Express"},
    {"info": {"rating": 5.7}, "year": 2004, "title": "The Prince & Me"},
    {"info": {"rating": 5.3}, "year": 2004, "title": "The Princess Diaries 2: Royal Engagement"},
    {"info": {"rating": 6.3}, "year": 2004, "title": "The Punisher"},
    {"info": {"rating": 6.8}, "year": 2004, "title": "The SpongeBob SquarePants Movie"}
]

任何人都可以向我提供一些有關如何進一步調查的提示或指示嗎？

Answer 1

response['Items'] 不是您要查找的列表嗎？ Response 是一個包含列表的字典，它只能是一個子集，因此您需要根據需要迭代多個響應。

參考： https : //boto3.amazonaws.com/v1/documentation/api/latest/reference/services/dynamodb.html#DynamoDB.Client.scan