在 DynamoDB 中更新以 python 中的数字开头的属性

Question

I have a nested object which may contain one attribute which starts with a numeric value.

The update Expression is something like this:

set attr1.attr2.#numericAttr.attr3 = :value

the expressionAttribute dictionary is this:

expressionAttrName:{#numericAttr: "29Wn5J8"}

My updateItem function of this type:

response = projectsTable.update_item(
                Key={
                    "ABC": "value",
                    "DEF": "value2"
                },
                UpdateExpression=expression,
                ExpressionAttributeNames=expressionAttrName,
                ExpressionAttributeValues=attribute,
                ReturnValues="UPDATED_NEW"
            )

when I run this, I get ClientException stating:

('An error occurred (ValidationException) when calling the UpdateItem operation: Invalid UpdateExpression: Syntax error; token: "29", near: ".29Wn5J8"',)

How to enable attributename to accept name starting with number?

Answer 1

As detailed in Expression Attribute Names in DynamoDB from the AWS Developer Documentation of DynamoDB:

Given the following table

{
  "AttributeDefinitions": [
    {
      "AttributeName": "some_pk",
      "AttributeType": "S"
    }
  ],
  "TableName": "test_table",
  "KeySchema": [
    {
      "AttributeName": "some_pk",
      "KeyType": "HASH"
    }
  ],
  "BillingMode": "PAY_PER_REQUEST"
}

With the following item

{
    "TableName": "test_table",
    "Item": {
        "some_pk": {
            "S": "ITEM1"
        },
        "some_map": {
            "M": {
                "nested_map": {
                    "M": {
                        "1234": {
                            "M": {
                                "inner_value": {
                                    "S": "1"
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

You can perform an update of some_map.nested_map.1234.inner_value , like so:

dynamo_client = boto3.resource('dynamodb')
table = dynamo_client.Table('test_table')
table.update_item(
    Key={
        'some_pk': 'ITEM1'
    },
    UpdateExpression='SET #attr1.#attr2.#attr3.#attr4 = :val1',
    ExpressionAttributeNames={
            '#attr1': "some_map",
            '#attr2': "nested_map",
            '#attr3': "1234",
            '#attr4': "inner_value"
        },    
    },
    ExpressionAttributeValues={':val1': '2'},
    ReturnValues='UPDATED_NEW'
)