使用 boto3 有条件地将项目插入 dynamodb 表中错误属性名称是保留关键字

Question

如果项目（状态）不存在，我将调用此函数来放置项目，这是我从这里引用的内容：How do I Conditionally insert an item into a dynamodb table using boto3 ..

    def put_items_if_doesnt_exist():
      dynamodb = boto3.resource('dynamodb',region_name='us-east-1')
      try:
          table = dynamodb.Table('awssolutions-ssm-hybrid-table')
          response = table.put_item(
          Item={
                  'name':'Execution',
                  'state': 'Locked',
              },
          ConditionExpression='attribute_not_exists(state) AND attribute_not_exists(name)'
          )
      except ClientError as e:
          # Ignore the ConditionalCheckFailedException
          if e.response['Error']['Code'] != 'ConditionalCheckFailedException':
              raise

这里的问题是状态是保留字，因此它失败并出现错误：

[ERROR] ClientError: An error occurred (ValidationException) when calling the PutItem operation: Invalid ConditionExpression: Attribute name is a reserved keyword; reserved keyword: state

有什么建议来处理这个问题吗？

Answer 1

这就是ExpressionAttributeNames进来的地方，他们允许您使用保留名称。您只需添加带有前缀的占位符#并在ExpressionAttributeNames参数中指定其值。

    def put_items_if_doesnt_exist():
      dynamodb = boto3.resource('dynamodb',region_name='us-east-1')
      try:
          table = dynamodb.Table('awssolutions-ssm-hybrid-table')
          response = table.put_item(
          Item={
                  'name':'Execution',
                  'state': 'Locked',
              },
          ConditionExpression='attribute_not_exists(#state) AND attribute_not_exists(#name)',
          ExpressionAttributeNames={"#state": "state", "#name": "name"}
          )
      except ClientError as e:
          # Ignore the ConditionalCheckFailedException
          if e.response['Error']['Code'] != 'ConditionalCheckFailedException':
              raise