DynamoDB Conditional Put_Item - amazon-web-services

Question

Hi Stackoverflow I'm trying to conditionally put an item within a DynamoDB table. The DynamoDB table has the following attributes.
ticker - Partition Key
price_date - Sort Key
price - Attribute
Every minute I'm calling an API which gives me a minute by minute list of dictionaries for all stock prices within the day so far. However, the data I receive from the API sometimes can be behind by a minute or two. I don't particularly want to overwrite all the records within the DynamoDB table every time I get new data. To achieve this I've tried to create a conditional expression to only use put_item when there is a match on ticker but there is a new price_date
I've created a simplification of my code below to better illustrate my problem.
import boto3
from boto3.dynamodb.conditions import Attr
dynamodb = boto3.resource('dynamodb')
table = dynamodb.Table('stock-intraday')
data = [
{'ticker': 'GOOG', 'price_date': '2021-10-08T9:30:00.000Z', 'price': 100},
{'ticker': 'GOOG', 'price_date': '2021-10-08T9:31:00.000Z', 'price': 101}
]
for item in data:
dynamodb_response = table.put_item(Item=item,
ConditionExpression=Attr("ticker").exists() & Attr("price_date").not_exists())
However when I run this code I get this error...
What is wrong with my conditional expression?

Answer 1

Found an answer to my own problem. DynamoDB was throwing an error because my code WAS working but with some minor changes.
There needed to be a TRY EXCEPT block but also since the partition key is already evaluated only the price_date needed to be included within the condition expression
import boto3
from boto3.dynamodb.conditions import Attr
from botocore.exceptions import ClientError
dynamodb = boto3.resource('dynamodb')
table = dynamodb.Table('stock-intraday')
data = [
{'ticker': 'GOOG', 'price_date': '2021-10-08T9:30:00.000Z', 'price': 100},
{'ticker': 'GOOG', 'price_date': '2021-10-08T9:31:00.000Z', 'price': 101}]
for item in data:
try:
dynamodb_response = table.put_item(Item=item,
ConditionExpression=Attr("price_date").not_exists())
except ClientError as e:
if e.response['Error']['Code'] == 'ConditionalCheckFailedException':
pass